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orangesuper
Samba Member
Joined: January 06, 2007
Posts: 371
Location: Moretown, VT
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 Posted: Wed May 24, 2023 6:12 am Post subject: EFI conversion fuel routing |
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| Apologize not really sure where to put this if it fits better in the bay window forum or here but I thought more people hanging out here may have done the EFI swap. I have a 1970 type 1 powered bay. I am in the process of converting it to EFI using the Mexican bug kit as the base and a Microsquirt. I’ve got an 1849cc built (thick wall 88sx76). I have been running this thing off a jetted up solex 34pict3 because I can’t fit dual carbs due to the auxiliary Gasoline heater on the left side of my engine bay. Anyway, I think I have all the components for the fuel injection swap finally in hand and I am in the process of putting it all together. I am trying to figure out how to route in the gas line for the heater. It seems most people just tee off the fuel port on the bottom of the tank and send the return from the fuel rails back into this tee. I have a little trouble having my brain wrap around the fact you can use one tee as a feed and a return without causing any issues but I suppose it works because plenty of people seem to be doing it. My problem is I need a second low pressure has feed to the Eberspacher heater pump. Any advise on where/how I get this piped in to the mix? |
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allamaabroad
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Joined: September 22, 2016
Posts: 560
Location: South Jordan, Utah
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| Posted: Wed May 24, 2023 7:04 am Post subject: Re: EFI conversion fuel routing |
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I see two options here, both are going to require some careful welding. Regardless of how you do it, you're going to need another inlet/outlet to the tank.
I think the ideal situation would be adding a return line fitting to the tank. This would allow you to use a T fitting to feed the EFI fuel pump and the gas heater, then just have a separate fitting for the return line from the engine.
Alternatively, you could also add a fitting for the heater. This fitting could just be at the bottom of the tank.
The one thing you can't do is try to combine them all together. When using a T for feed/return with EFI, the return line ends up pressurizing the feed line. The pressure in the feed line could potentially reach the pressure of your fuel rails (40-50 psi) which your heater won't like very much.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed May 24, 2023 7:09 am Post subject: Re: EFI conversion fuel routing |
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| orangesuper wrote: |
| Apologize not really sure where to put this if it fits better in the bay window forum or here but I thought more people hanging out here may have done the EFI swap. I have a 1970 type 1 powered bay. I am in the process of converting it to EFI using the Mexican bug kit as the base and a Microsquirt. I’ve got an 1849cc built (thick wall 88sx76). I have been running this thing off a jetted up solex 34pict3 because I can’t fit dual carbs due to the auxiliary Gasoline heater on the left side of my engine bay. Anyway, I think I have all the components for the fuel injection swap finally in hand and I am in the process of putting it all together. I am trying to figure out how to route in the gas line for the heater. It seems most people just tee off the fuel port on the bottom of the tank and send the return from the fuel rails back into this tee. I have a little trouble having my brain wrap around the fact you can use one tee as a feed and a return without causing any issues but I suppose it works because plenty of people seem to be doing it. My problem is I need a second low pressure has feed to the Eberspacher heater pump. Any advise on where/how I get this piped in to the mix? |
You can't...or should not....do the tee like that. People do the "tee" because they mostly get away with it. The concept is not wrong....just that a tee right at the fuel tank outlet with one leg going out and one coming in causes turbulence at that junction in the main line. If they were both going out from the tank it's only a very small amount of internal turbulence mainly for the leg going left or right. It's not an issue.
Then there is the need for your heater supply.
There are two main ways that the factory did this which worked well.
1. Plumb it with a "Y" not a "T" fitting. The Y fitting was used in all fuel injected type 3 and 4 cars. The factory knew about the potential issues which is why they used both a Y and an in-line harmonic damper.
Why? Because the turbulence caused by a T in this position will either cause a possible feed issue with some pumps (especially early D-jet pumps)....at worst....but at least it causes an oscillation. A harmonic that gets very noisy at times.
The factory fitting to feed back to the tank from the pump relief valve looked like this:
https://www.amazon.com/QFS-FTY-38-Quantum-Y-Fitting-Assembly-Splitter/dp/B08BW6Y1F8
2. The other way if you use a T instead of a Y is to make a small reservoir at the leg of the T where the return line enters the T. And, that reservoir can also feed the heater.
The reservoir allows fuel some place to back up to when the main leg of the T is pulling harder past the port. It really just acts like the original in line harmonic damper did in a lot of the early systems.
Type 4 cars had a special in-line reservoir like I am describing....just for feeding the heater from the return line. They are quite rare. I will post the part number later and a picture. But you can easily make one out of some pipe fittings and barbs that will work just fine.
Ray |
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orangesuper
Samba Member
Joined: January 06, 2007
Posts: 371
Location: Moretown, VT
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| Posted: Wed May 24, 2023 7:27 am Post subject: Re: EFI conversion fuel routing |
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| raygreenwood wrote: |
2. The other way if you use a T instead of a Y is to make a small reservoir at the leg of the T where the return line enters the T. And, that reservoir can also feed the heater.
The reservoir allows fuel some place to back up to when the main leg of the T is pulling harder past the port. It really just acts like the original in line harmonic damper did in a lot of the early systems.
Type 4 cars had a special in-line reservoir like I am describing....just for feeding the heater from the return line. They are quite rare. I will post the part number later and a picture. But you can easily make one out of some pipe fittings and barbs that will work just fine.
Ray |
Something like this? A picture of how that type 4 is set up would be great thanks
https://fastech-racing.com/righetti-km895-2.html |
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed May 24, 2023 9:34 am Post subject: Re: EFI conversion fuel routing |
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| orangesuper wrote: |
| raygreenwood wrote: |
2. The other way if you use a T instead of a Y is to make a small reservoir at the leg of the T where the return line enters the T. And, that reservoir can also feed the heater.
The reservoir allows fuel some place to back up to when the main leg of the T is pulling harder past the port. It really just acts like the original in line harmonic damper did in a lot of the early systems.
Type 4 cars had a special in-line reservoir like I am describing....just for feeding the heater from the return line. They are quite rare. I will post the part number later and a picture. But you can easily make one out of some pipe fittings and barbs that will work just fine.
Ray |
Something like this? A picture of how that type 4 is set up would be great thanks
https://fastech-racing.com/righetti-km895-2.html |
Ooooh...damn that looks like a sweet part! I will have to see what the volume looks like but its not far off from factory.
Ok...in the diagram below, part #7 is the "Y". It is used in reverse of the way you will be using a Y with your fuel tank and modern pump. Its part # is 311 133 525
Because there was a return line from the pump and from the fuel pressure regulator and there was also a return port in the tank outlet alongside the supply port.
They used a "Y" instead of a "T" to return the fuel because the return line from the fuel injection regulator had higher volume....but the return bleed from the pump was higher pressure. With a "T"...these two inlets fight each other. Turbulence and poor flow results.
In your system you flip the T around. It looks awkward but you need to think about this like a traffic Y on an interstate on ramp. You would not merge at 70 mph with a dead end T. It would look like this:
Just for reference the "harmonic damper" I have been speaking of is part #8 on the diagram and its part # is 311 133 531
Down by item # 49, circled in yellow you see a little inline reservoir to feed the heater unit and it has no number in this diagram but you can get the concept. I found it in the heater pages as item # 38 in the diagram and part # 311 261 277 and they call it a "deaerator" ....which kind of makes sense. Its designed to make sure the metering pump has solid fuel to draw from so it does not suck air.
If you Google that part # you will come up with mostly transmission parts.
AND....and...and....that Rhighetti part would be IDEAL to use in stead of T or a Y...because it really does the exact same thing. It prevents stoppage and turbulence between intersecting fuel flow directions.
You could plumb that to the tank instead of a Y and also...get a second one to put inline just downstream of the fuel pressure regulator in the return line...to feed the heater.
$29 each sounds like a lot but its an elegant solution to both issues. Ray |
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orangesuper
Samba Member
Joined: January 06, 2007
Posts: 371
Location: Moretown, VT
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| Posted: Wed May 24, 2023 10:36 am Post subject: Re: EFI conversion fuel routing |
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Thanks Ray for putting the time into that. I think I am following forgive the crude drawing is this what you are suggesting?
[/img] |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed May 24, 2023 11:47 am Post subject: Re: EFI conversion fuel routing |
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| Yes! With that neat little fuel reservoir that would be a clean install. Ray |
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Chip 
Samba Member
Joined: July 19, 2008
Posts: 969
Location: Utah
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| Posted: Wed May 24, 2023 11:53 am Post subject: Re: EFI conversion fuel routing |
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| orangesuper wrote: |
Thanks Ray for putting the time into that. I think I am following forgive the crude drawing is this what you are suggesting?
[/img] |
I'd recommend a filter after your pump as well. Large micron before the pump, small one after. I think my last build was 100 before and 20 after. |
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clonebug
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Joined: January 29, 2005
Posts: 4027
Location: NW Washington
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| Posted: Wed May 24, 2023 7:24 pm Post subject: Re: EFI conversion fuel routing |
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I've been running a Tee under my tank with EFI for 10 years and 51,000 miles.
To say it doesn't work is not a true statement. I've never had a fuel issue in that time and mileage period.
Here is my Tee, It's a little different now since I removed the brass nipples and use JIC fittings instead for easier removal and replacement of the tank. My pump does have a 1/2 inch inlet to the pump and I use the stock line for the return.
Here is the Volvo pump and a Golf EFI filter. I have a standard Napa prefilter in the line before the pump.
I would think you could run a line off the return side and regulate the pressure to the heater without an issue. It should always be fairly low pressure.
If I was concerned I could move my pressure sensor to the fuel return line and monitor the pressure but I doubt it would be an issue.
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UK Luke 72
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Location: Little Britain
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Wreck
Samba Member
Joined: July 19, 2014
Posts: 1218
Location: Brisbane
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| Posted: Thu May 25, 2023 5:36 am Post subject: Re: EFI conversion fuel routing |
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| clonebug wrote: |
I've been running a Tee under my tank with EFI for 10 years and 51,000 miles.
To say it doesn't work is not a true statement. I've never had a fuel issue in that time and mileage period.
Here is my Tee, It's a little different now since I removed the brass nipples and use JIC fittings instead for easier removal and replacement of the tank. My pump does have a 1/2 inch inlet to the pump and I use the stock line for the return.
Here is the Volvo pump and a Golf EFI filter. I have a standard Napa prefilter in the line before the pump.
I would think you could run a line off the return side and regulate the pressure to the heater without an issue. It should always be fairly low pressure.
If I was concerned I could move my pressure sensor to the fuel return line and monitor the pressure but I doubt it would be an issue. |
I tried this and had cavitation issues , it ran but was noisy . I ended up moving the return into a Tee in the fuel filler 1/2 " breather tube. (1969 Ghia ) . pump is a bosch 044 . quiet as a mouse now . |
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esde
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Joined: October 20, 2007
Posts: 5969
Location: central rust belt
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| Posted: Thu May 25, 2023 5:55 am Post subject: Re: EFI conversion fuel routing |
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I ran a bulkhead fitting into the top of my tank for the return. Tightening it was easy once I removed the gauge sender. I have a -4 line as the return. Zero issues, and you cannot hear the fuel splashing at all
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu May 25, 2023 6:29 am Post subject: Re: EFI conversion fuel routing |
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| clonebug wrote: |
I've been running a Tee under my tank with EFI for 10 years and 51,000 miles.
To say it doesn't work is not a true statement. I've never had a fuel issue in that time and mileage period.
Here is my Tee, It's a little different now since I removed the brass nipples and use JIC fittings instead for easier removal and replacement of the tank. My pump does have a 1/2 inch inlet to the pump and I use the stock line for the return.
Here is the Volvo pump and a Golf EFI filter. I have a standard Napa prefilter in the line before the pump.
I would think you could run a line off the return side and regulate the pressure to the heater without an issue. It should always be fairly low pressure.
If I was concerned I could move my pressure sensor to the fuel return line and monitor the pressure but I doubt it would be an issue. |
And carefully note.....i did not say it does not work.
Notice that I said many get away with it.
Also make note that Wreck ran a Tee and had cavitation issues.
Whether a simple Tee works or not without cavitation or flow limitation......depends on a whole lot of little variables that no one really has tools to measure.
Like:
How full your tank is (static pressure)
Height of tank above pump
Height of pump below engine
Type of fuel filter
Diameter of your hoses
Build quality, pump type (turbine, sliding vane, roller cell) and connections
Whether your pump has a check valve (it should) and what pressure setting it is
Design and pressure level of your fuel pressure regulator
Whether you have any type of in-line accumulator
Lots of things can affect it.
I have seen cavitation with a Tee more often than not. But then again I have not used every pump on the market.
My point was, a Tee is not the correct part for this position in the fuel system (or many other type of flow restriction sensitive fluid systems). It's why they make "Y's" in the first place!
I should have qualified tlmy statement with....your results may vary!
Also, use of a Tee....many times .....is the root cause of poor fuel pressure stability when nothing else really seems to indicate that anything is wrong.....meaning no noise, engine runs, pump runs cool etc.
Ray |
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orangesuper
Samba Member
Joined: January 06, 2007
Posts: 371
Location: Moretown, VT
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| Posted: Wed May 31, 2023 5:41 pm Post subject: Re: EFI conversion fuel routing |
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| Just wanted to follow up I bought those mini reservoir parts and they arrived today. They are roughly 35mm film canister sized for reference and are pretty slick. I was just reading through some stuff on thedubshop website and noticed it says to remove the “fuel sock” which I assume references an in tank filter. I wish I had noticed that before I put my firewall all back together this afternoon which is a pain with the BN4 heater through it. I am assuming that I should go ahead and tear it back apart and pull the tank and remove that? |
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MuzzcoVW
Samba Member
Joined: February 21, 2018
Posts: 1475
Location: Westfield, MA.
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| Posted: Thu Jun 01, 2023 3:23 am Post subject: Re: EFI conversion fuel routing |
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| raygreenwood wrote: |
| orangesuper wrote: |
| Apologize not really sure where to put this if it fits better in the bay window forum or here but I thought more people hanging out here may have done the EFI swap. I have a 1970 type 1 powered bay. I am in the process of converting it to EFI using the Mexican bug kit as the base and a Microsquirt. I’ve got an 1849cc built (thick wall 88sx76). I have been running this thing off a jetted up solex 34pict3 because I can’t fit dual carbs due to the auxiliary Gasoline heater on the left side of my engine bay. Anyway, I think I have all the components for the fuel injection swap finally in hand and I am in the process of putting it all together. I am trying to figure out how to route in the gas line for the heater. It seems most people just tee off the fuel port on the bottom of the tank and send the return from the fuel rails back into this tee. I have a little trouble having my brain wrap around the fact you can use one tee as a feed and a return without causing any issues but I suppose it works because plenty of people seem to be doing it. My problem is I need a second low pressure has feed to the Eberspacher heater pump. Any advise on where/how I get this piped in to the mix? |
You can't...or should not....do the tee like that. People do the "tee" because they mostly get away with it. The concept is not wrong....just that a tee right at the fuel tank outlet with one leg going out and one coming in causes turbulence at that junction in the main line. If they were both going out from the tank it's only a very small amount of internal turbulence mainly for the leg going left or right. It's not an issue.
Then there is the need for your heater supply.
There are two main ways that the factory did this which worked well.
1. Plumb it with a "Y" not a "T" fitting. The Y fitting was used in all fuel injected type 3 and 4 cars. The factory knew about the potential issues which is why they used both a Y and an in-line harmonic damper.
Why? Because the turbulence caused by a T in this position will either cause a possible feed issue with some pumps (especially early D-jet pumps)....at worst....but at least it causes an oscillation. A harmonic that gets very noisy at times.
The factory fitting to feed back to the tank from the pump relief valve looked like this:
https://www.amazon.com/QFS-FTY-38-Quantum-Y-Fitting-Assembly-Splitter/dp/B08BW6Y1F8
2. The other way if you use a T instead of a Y is to make a small reservoir at the leg of the T where the return line enters the T. And, that reservoir can also feed the heater.
The reservoir allows fuel some place to back up to when the main leg of the T is pulling harder past the port. It really just acts like the original in line harmonic damper did in a lot of the early systems.
Type 4 cars had a special in-line reservoir like I am describing....just for feeding the heater from the return line. They are quite rare. I will post the part number later and a picture. But you can easily make one out of some pipe fittings and barbs that will work just fine.
Ray |
I've been doing the Tee on my '75 F.I. Bug for a few years as no one produces standard Bug F.I. tanks. It works great... for me. It was actually recommended by several here. I guess it's one of those YMMV things. We'll see how it does on my upcoming 1904 F.I. engine but I don't forsee an issue |
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boxer74
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Joined: July 03, 2011
Posts: 709
Location: Ontario, Canada
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| Posted: Thu Jun 01, 2023 1:51 pm Post subject: Re: EFI conversion fuel routing |
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Instead of having to run another fuel line to the engine bay in a bug, could something like this be used?
https://www.amazon.ca/dp/B08F53LL3N/?coliid=I33KI4..._lig_dp_it
Put the pump between it and the tank, and a return line from it back to the tank. Locate it all under the tank. Then use the existing supply line in the tunnel to feed the fuel rails.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Jun 01, 2023 2:30 pm Post subject: Re: EFI conversion fuel routing |
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| boxer74 wrote: |
Instead of having to run another fuel line to the engine bay in a bug, could something like this be used?
https://www.amazon.ca/dp/B08F53LL3N/?coliid=I33KI4..._lig_dp_it
Put the pump between it and the tank, and a return line from it back to the tank. Locate it all under the tank. Then use the existing supply line in the tunnel to feed the fuel rails. |
Yes and no.
You have to have a return line from the fuel rail. Unless you have sensors, logic and a variable electromechanical regulator....you do not want to "dead head" the supply to the fuel rail.
That filter design IS what is used on virtually all VW and Audi cars from about mk4 onward....and for very good reason. It is directly responsible for maintaining very uniform and spike free fuel pressure. It IS the fuel pressure regulator.
The object of it is that the regulation is done very close to the pump and very far from the fuel rail. All fuel pressure regulators create an oscillation as the spring loaded valve cracks open and snaps closed numerous times per second. The pump itself with its check valve creates an oscillation cycle of about 20-30 times per second.
The return line coming from the filter/regulator keeps these oscillations away from the fuel rail where older systems had their regulator . Distance also damps Oscillation frequency.
So this type of filter/regulator is a great way to go with any EFI system. Fuel pressure is key. Modern systems need stability within about 1/2 psi.
This filter generally comes in two specs ....a 4 bar (58 psi) and a 6.6 bar (95.7 psi). But most of the systems that use then still have a return line from the rail....usually also with a final harmonic, in-line diaphtagm type harmonic damper at the end of the rail.
You need to run a return line. Its not that big of a deal. It's low pressure. Use modern connectors and nylon fuel tube.
I also would certainly not spend $72 on that filter. The stock VW and Audi filter is VERY accurate pressure wise and well built. You can buy the stock Mann & Hummel filter in either 4 or 6.6 bar from Rock Auto for about $31. Same price for Wix. Hengst which is also a great and accurate brand is $22.
https://www.rockauto.com/en/catalog/volkswagen,201...ilter,6200
I just bought one for my Golf last week.
But....do not buy the Hengst from Rockauto until they fix their catalog. They have the 4 bar listed with the 6.6 bar part # and vice versa. I got the 6.6 bar when I needed the 4 bar and just sent it back yesterday.
I will be installing one of these in my 412 when it gets back on the road. But....my injection system requires 28 to 31 psi. This would create too much pressure for the injectors and too much fuel for the system to adjust for via pulsewidth.
The way I will be using this is fuel pump is from the pump---- 4 bar filter with return at the tank--- original 28 psi regulator up close to the tank instead of back at the fuel rail---return line to "Y" at the return line from the 4 bar filter/regulator----harmonic damper on-line at the "Y".
My testing has shown that this can produce better than +/- 0.5 psi fuel pressure stability at the rail.
Why this works so well partly....is that it keeps the much larger than necessary pump revved up and loaded to a uniform pressure against the regulator restriction at a volume and pressure that is far higher than you need....like about 2x.
This means that the actual usage by the engine causes very little line pressure drop every time the main 28psi regulator cracks open several times per second.
This damps Oscillation.
Ray |
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boxer74
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Joined: July 03, 2011
Posts: 709
Location: Ontario, Canada
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| Posted: Thu Jun 01, 2023 3:25 pm Post subject: Re: EFI conversion fuel routing |
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But Ray, this filter design doesn't dead head at the rail. It has a return line back to the tank. What I'm after is saving having to run a return from the rails at engine all the way back to the tank. Can this work?
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Jun 01, 2023 7:24 pm Post subject: Re: EFI conversion fuel routing |
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| boxer74 wrote: |
| But Ray, this filter design doesn't dead head at the rail. It has a return line back to the tank. What I'm after is saving having to run a return from the rails at engine all the way back to the tank. Can this work? |
Yes...and you are pumping 58 psi to the rail with no outlet from the rail. That is called "dead heading".
The return line from the filter is not a return from the filter outlet that goes to the rail.
The inlet and outlet is simply regulating the pressure that feeds the rail. It is not venting the rail.
The other thing that happens on a dead head rail set up is that unless you can maintain pressure perpetually with great check valves and a fuel accumulator, once it bleeds down, without pressure, fuel evaporates and you get vapor in the rail.
This means that you have to crank and crank and crank until all of that vapor is injected into the engine ahead of the fuel. On a loop system with a return you simply buzz the pump and it pumps fuel through the whole loop chasing the vapor back into the tank.
You need a return line.
Ray |
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boxer74
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Posts: 709
Location: Ontario, Canada
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| Posted: Thu Jun 01, 2023 8:38 pm Post subject: Re: EFI conversion fuel routing |
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Ok thanks.
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