Electric Fuel Pump

[mondshine]

Here’s a brief rundown of the electric fuel pump installation on my ’73.

As my Kubel Treffen friends remember, I had several instances of a pesky vapor lock problem during my trip to and from the 2021 Kubel Treffen East in Flat Rock, NC this July.
From my home, it’s about a 650 mile drive each way.

I was using a standard Pierburg/VW square top fuel pump. For the entire round trip, oil temperature and cylinder head temperatures were well within acceptable maximums; OT never over 225º, CHT never over 325º.

After each vapor lock konk-out, pouring cool water onto the fuel pump would bring it right back to life. I had confirmed that the pump push rod was not sticking in the plastic spacer when hot.

Anyway, when I returned home, I re-routed the fuel lines (with as much distance as possible from the intake manifold) and increased the fuel pressure to 3.5 PSI.
Everything seemed to be OK after that, but 3.5 PSI seemed a little excessive, so I decided to install an electric pump under the fuel tank.
Besides, after those vapor lock experiences, that mechanical pump was making me “nervous in the service”; I never want that sort of thing to happen again.

I suppose I could listen to some guy tell me how he drove across the desert 200 times without any problems with a mechanical pump, but I had to base the decision to go with an electric pump on my own personal experience.

So which pump to use?
Both Pierburg and Hardi make electric pumps (in Germany) but the “low pressure” Pierburg pump outputs close to 10 PSI, and the Hardi pump is a diaphragm (clicketty clack) type, which I did not want. They are also (both) a little hard to get.

So I went with the Carter P90091 pump.

It is a rotary pump with a 3/8” inlet barb, and a 5/16" outlet barb. I wasn’t very happy about the electrical connections; which are spade lugs, so I crimped open barrel terminals to the supply wires, and then soldered them in place onto the pump terminals. They are sealed with marine (adhesive lined) heat shrink tube. The two supply wires are connected to the car with AMP “super seal” locking connectors, so I expect the electrical connections to the pump to be water and vibration proof.
The pump is mounted with the furnished band clamp onto a rubber vibration isolator, then to the pan under the fuel tank. It is very quiet; much more so the my old CIS pump (but that pump was more than twice the size, and output ~70 PSI).

The Carter pump is powered through a Revolution Electronics fuel pump controller. I had used this controller to power the CIS injection pump on my old Thing.
It works like the “Rabbit relay” with better reliability. The RE controller gives a 3 second pulse to prime when the ignition is switched on, then requires a tach signal to keep the pump running.

The RE controller's internal relay is rated at 7.5 Amps, but The RE controller is set up to trigger a standard Bosch relay.
I measured the Carter pump current draw (between the relay socket terminals 30, 87) at only 1.4 Amps, however, I like having the ability to easily bypass the controller (with my handy-dandy relay bypass device) in an “emergency”.

This is my handy-dandy relay bypass gimmick:

I have installed a Malpassi “Petrol King” regulator in the engine compartment. It is a “deadhead” regulator, but it is only reducing the fuel pressure from 4.5 PSI to 2.5 PSI, so I think it will be OK.
The regulator is mounted with a home made bracket attached to two of the many M5 studs on the forward bulkhead of the engine compartment (Thanks VW, for putting a million M5 studs all over the place on that forward bulkhead).

The regulator is that "flying saucer" thing above the fan shroud.

So… This was a fun project. Fuel pressure output through the Malpassi regulator (2.5 PSI) is rock steady, and for now… I’m happy.

Good luck, Mondshine

[yel-mel]

Mondshine
Wow this is a great project......very nice work !

Can't beleive 200 looks and no one commented?

Thing folks are very very quiet.....

[[email protected]]

WOW, I love it, but am too intimidated to even try.

[mondshine]

I have decided to re-locate my Carter pump to the front beam.

I did this so that the pump could be serviced or replaced without lifting the car, removing a wheel or the fuel tank, etc. (Thinking "side-of-the-road" here.)

Now the pump is mounted to the front beam using an American style muffler clamp; basically a 2" U-bolt. My Fram HPG1 fuel filter has been mounted this way for over 20 years, and now, the Carter pump is mounted to an additional clamp, right next to the filter.

The muffler clamp holding the pump has 5/16-18 threads, and is threaded directly into a (male x female) rubber vibration isolator, which holds the pump in its furnished mount.

Sketch:

The entire mess is "protected" by a small sheet of 1/4" thick ABS plastic.
It is held on the beams with cushioned "P" clips, M6 screws and coupling nuts.

All in all, a neat package, and easy access for potential repairs.

Edit:
This pump is very quiet; barely audible with the engine off, and not at all with the engine running. So once again, for now... I'm happy.

[yel-mel]

From what I can see your engine compartment is spotless !
Is the tube on the top a chemical fire extinguish hose ?

[mondshine]

Lots of stuff in this engine compartment is from my old (wrecked) Thing, including that "BlazeCut" fire suppression gizmo.

[Elroyyy]

Curious if you'd considered the Ford Ranger (Airtex E2000) fuel pump that the Type 3 crowd uses?
_________________
My Classified Ads

[mondshine]

[Hyatt181]

Gary would you be able to post a picture of the front beam from the front and rear?
I'm having trouble seeing how this is all put together.

The drawing seems to have it on the driver's side but I can't see how that would work with the steering box. Maybe I'm seeing it from the front so that would be on the passenger side. Then i'm assuming you have a plate in front of the pump based on the drawing?

Maybe I just need to come look at it in person.

[Hyatt181]

Read through this again and was able to answer my questions.
Gary you're one hell of resource for ideas.
Thanks for taking the time and putting it into drawings.

[doublecanister]

Hey Gary,

where'd you end up mounting the Revolution device? under dash area somewhere?

And the bypass adapter, do you swap that out for an existing relay in an emergency??
well after reading it again it appears you do use a relay AND this revolution device... just trying to wrap my head around it.
I've never hooked up a electric fuel pump....yet.

Mulling a electric fuel pump myself, it's bad we have to think ahead for roadside repairs but it keeps you rollin'

Thanks Gary!
and as always very nice work.

T
_________________
****************************************
2020 - Mustang Eco Boost [High Performance]
1973 - Thing
1966 - Mustang GT- Fastback
1951 - Ford F1 pickup Flathead V8

[mondshine]

Hi Tom-

I used the RE fuel pump controller to trigger a standard Bosch relay, because that is the way it was set up when the same RE controller was switching my CIS fuel injection pump on my old Thing. That CIS pump, along with other electric components of the CIS system had a total current draw which was too close to the maximum current rating of the RE controller.
The RE controller is one of the parts I "transplanted" to the "new" Thing.

On my "new" Thing, the current draw of the Carter P90091 pump is so low that the Bosch relay is redundant; only the socket that it is plugged into is an easy place to bypass it if necessary.

All of my Thing's relays are on a single relay panel on the underside of the trunk floor, between the steering column and the BN4 air inlet. It is actually held in place by two of the rubber standoff studs from the BN4 heater (no new holes).

But the RE controller is pretty small; maybe 1"x1.5"x2", so it could easily fit behind a dash panel.

If I drive my Thing to the Kubel Treffen, you can look it over in July.
If I have too much stuff to bring, or if rain is forecast for the entire weekend, I will probably drive my regular car; everybody has seen my Thing a million times anyway.

One of our new KTE guests is a witch (really), so I have asked him to guarantee dry weather. Time will tell.

[doublecanister]

Ok thanks Gary,

I do like the idea of the bypass method for an emergency, I may have to figure out how to do that if I don't use a relay.

Anything to do roadside troubleshooting and take the fun out of it is a good idea!

I've bought one of the fuel pumps from CB's (it looks like the carter) as I'm trying to rid myself of the hot start issue, coming home from Appomattox
last year I almost ran out of gas, happened to stop a a lil' country store that had 2 pumps out front with someone parked there, only to find they hadn't sold gas in 8 years! Then I couldn't get the Thing to fire up again took way more tries than usual it finally did...whew!
https://www.cbperformance.com/product-p/3193.htm

Anyways I think i'm going to get that Revolution device, Hope I can get all this done by showtime, it's Springtime and our work has gone crazy busy with growing season.

Thanks again for the info and yes, hoping for no rain, we've had plenty!

T
_________________
****************************************
2020 - Mustang Eco Boost [High Performance]
1973 - Thing
1966 - Mustang GT- Fastback
1951 - Ford F1 pickup Flathead V8

[Olli from NJ]

Mondshine,

I've used the RE fuel pump controller in a few different cars and wired it up according to their instructions. That additional relay isn't required ( but you already had it and you stated that it was redundant) as the RE controller has a built in relay. The Revolution Electronics fuel pump controller is actually a very straight forward install and I will definitely be using it again the next time I install an electric fuel pump. It is a great product that has proven very reliable in two cars that I have.

https://www.revolutionelectronics.com/Products/Fuel_Pump.html

https://www.revolutionelectronics.com/12003-installation-2.pdf

Olli

[Heiferman]

I had not considered running just a single electric pump for both the engine and BN4. My PO had two pumps bodged in below the gas tank. Brilliant.

Gary - in your diagram it looks like you have an in-line filter before the BN4 heater - is that what you are showing in the diagram?
Also, what did you use or where did you step everything down to 1/4 inch line to get to the carb?

Also, other than the large hpg1 are you running any other filters before the carb?

Last question - with the large filter, are you still running the inside the tank screen above the bung?

Cheers

[mondshine]

First of all, you cannot use a single pump to supply fuel to the engine and to the BN4. The BN4 requires a dedicated "dosing pump" which sends a pulse of fuel once per 33 revolutions of the BN4's fan motor. Mine is set to deliver 14cc of fuel for every 200 clicks of the pump.

On the illustration, the filter outlet labeled "BN4" is actually connected to the BN4 pump inlet.

Here is a tongue in cheek video of "bench testing" the BN4 pump triggered by an electronic device set to provide 200 pulses.

Link


My HPG1 filter is my only filter for the carburetor; I have cleaned the steel tube inside the tunnel. I never have problems with trash in the carburetor bowl.
My BN4 has an additional filter on the stock bracket attached to the front bulkhead. It is just one of those cheap plastic things. That filter is pretty well protected in its stock location, and it sees negligible pressure and volume.

My fuel tank came from my previous Thing which had CIS fuel injection, so that tank has two JIC-8 fittings (inlet, outlet) welded in place, with the return fitting capped.
The mesh screen inside the tank is long gone.

This is the fuel hose I use:
https://belmetric.com/eckstein-braided-multi-fuel-rubber-hose/?sku=RHM5.5BRAIDECK

Hope that is helpful, good luck, Mondshine

[Heiferman]

Thanks for that quick response. I have never had a gas heater in a VW so this is totally new to me. I appreciate the schooling.
I have always found the bungs on the bottom of these fuel tanks a little finnicky as the car ages. I actually did consider replacing it with an AN fitting and run that stuff all the way back to the engine but my OEM hard line seems clean and in good nick.