I Need Help with L-Jet / AFC Fuel Injection Topic

TGOT · Posted: Sun May 27, 2012 10:30 pm Post subject:

Colin suggested in a PM to swap injector from side to side and see if the problem followed and it may be a flow problem. Unfortunately it did not affect the situation.

We are out of ideas now. Im going to just keep cracking and re checking things but if anyone has a direction to push Id appreciate it.
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71 Super Sold
76 Westy Sold
99 Beetle TDI Sold
81 Rabbit Diesel Sold
79 Sunroof Bus Sold

I miss all of them but I still have a

76 Adventurewagen Hightop FI

SGKent · Posted: Mon May 28, 2012 12:14 am Post subject:

It is either electrical and one side is getting more voltage or a better ground so that the injectors work better, or the cylinders on the 3/4 side are getting air from another source that is downstream of the injectors such as cracks in the head or loose cylinders to head.

Another possibility if you still have the EGR valve is that that tube inside the plenum is partially clogged and as a result one side is getting more oxygen poor air than the other. If the EGR is still connected try blocking it with a piece of aluminum from a pop bottle at the filter. You can undo the two bolts (use a little penetrating oil on them first) then hold the pieces together temporially with two vice grips. if that isn't it then pull the piece of aluminum tin and tighten the bolts back up.

The EGR gasses have no oxygen in them as they are exhaust. They come out of a tube inside the plenum that has holes even,y placed in it so that ll the cylinders get an equal amount of inert gasses. The tubes plug up so that one side can get all the EGR gasses thus killing that cylinder(s) making them really rich while the others are lean.
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Steve aka Merlin the Wrench

formerly Steve's Racing and Engine Blueprinting. Wrenching since 1967.

bdamico on GF wrote

babysnakes · Posted: Mon Jun 04, 2012 1:45 pm Post subject:

I'm finally getting off my fat arse and have started working on the FI for the '78 Westy. The injectors are #0.280.150.100, 2.1 ohm 186cc @ 3 Bar. One of them is damaged from what looks like fire coming through a bad valve (tip is somewhat melted). I have a spare set of injectors # 0,280.150.114, 2.2 ohm 190cc @ 3 Bar. I talked to the fella @ Witch Hunter and was told there is no difference. Trying to cover my posterior can these be mixed together and work fine? should I stay with the injectors that came with the bus? Or can I use the spares? I'm new at this and trying to do it right. These are going into a new Adrian built engine.
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'69 SC under resto
'72 deluxe daily
'78 Westy motor transplant in progress
'71 super vert
1st bus, '67 Westy in '83. Thank you '74 Pontiac Ventura.
Luftwagens

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borninabus · Posted: Mon Jun 04, 2012 5:12 pm Post subject:

the only real difference i am aware of is one style of injector has a removable hose and one doesn't.
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babysnakes · Posted: Mon Jun 04, 2012 5:29 pm Post subject:

The spares have braided hose and are shot. The '78s are solid hose and look good. I'm sure either hoses could be replaced (dremel through the compression fitting).
_________________
'69 SC under resto
'72 deluxe daily
'78 Westy motor transplant in progress
'71 super vert
1st bus, '67 Westy in '83. Thank you '74 Pontiac Ventura.
Luftwagens

420GOAT wrote:
..dont ever ever ever ever EVER, compare any bus forum to a bug forum...

SGKent · Posted: Fri Jun 08, 2012 4:29 pm Post subject:

the plastic tips and internal screens are replaced when WitchHunter goes through them. Maybe they can sell you a set of tips. We sent ours to them and were pleased with the turn around and results. I actually sent 2 sets and then chose the best matched of the 8.
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Steve aka Merlin the Wrench

formerly Steve's Racing and Engine Blueprinting. Wrenching since 1967.

bdamico on GF wrote

MadFrankie · Posted: Sun Jun 10, 2012 2:41 am Post subject:

Westfabulous · Posted: Sun Jun 10, 2012 9:43 am Post subject:

SGKent · Posted: Sun Jun 10, 2012 7:35 pm Post subject:

there are two wires to the pump. Make sure you are measuring voltage across the spade lugs which are part of the pump juat in case you have a bad ground wire.
_________________
Steve aka Merlin the Wrench

formerly Steve's Racing and Engine Blueprinting. Wrenching since 1967.

bdamico on GF wrote

MadFrankie · Posted: Mon Jun 11, 2012 3:03 pm Post subject:

H guys,

Tried the afm flapper at the weekend and nothing, not a peep from the pump.

I also checked the voltage across the 2 wires and got a reading so it looks like from my testings and from all your wonderful help that it's the pump.

Now to find one, rocking horse mess anyone?

SGKent · Posted: Mon Jun 11, 2012 3:48 pm Post subject:

vwheritage has some although the photo they show is one that has bolt on connectors so you will have to cut off the connector ends and crimp new ones on. I believe the original bosch unitswith spade style connectors can still be gotten through BusDepot in the USA.
_________________
Steve aka Merlin the Wrench

formerly Steve's Racing and Engine Blueprinting. Wrenching since 1967.

bdamico on GF wrote

pgtips · Posted: Wed Jun 13, 2012 1:45 am Post subject:

Hi,
if you do a search on samba for the VW fuel pump specs you'll start to come up with some alternatives, Ford Rangers (no use if you are UK though), Airtex E2000 (which I found on Amazon US so might also be available UK) and Bosch 69414 Original Equipment Replacement Elecric Fuel Pump, also on Amazon. There are quite a few alternatives, about £60 ish quid.

I think the key is to get a fuel pump that will deliver 60 psi. All the info I have found in the searches suggest that is the range. Then find a pump to match.

Theres going to be a regulator in there somewhere to ensure it doesn't put out too much.
Which does raise a Q in my head, does the regulator just limit it to a set amount. If you can find a pump to match that you will be sorted.

PG

Randy in Maine · Posted: Wed Jun 13, 2012 3:47 am Post subject:

Actually a fuel pump just puts out volume, not pressure. It is the fuel pressure regualtor that does that part.

A good pump will deliver about 1L of fuel in 30 seconds.

pgtips · Posted: Wed Jun 13, 2012 5:59 am Post subject:

good point, Does that mean / or are you saying pretty much 'any' good fuel pump coupled with a regulator restricted to 60 psi ?

If that is the case thats quite useful to know, I have thought about my pump recently and what I would do if it gave up on me (I don't know its history or age).

I know regulators can be pretty generic, I have been trying to find one for a decent price for my carb based VW which would be as low as 2 psi but I have seen plenty of regulators are much higher (for FI) and also adjustable.

So that just leaves a half decent fuel pump that, at a guess, must be able to deliver min 60 psi, or as you say 1L of fuel in 30 seconds whatever that may be in pressure - which could also be a generic item. That widens the scope for what could be used without tying me up to hard to find/expensive/ages to get fixed.

Randy in Maine · Posted: Wed Jun 13, 2012 11:49 am Post subject:

Two different fuel pumps we are speaking of....

A fuel injection pump is the one that puts out ~ 1L of fuel in 30 seconds. Normal operating pressure is <40 psi. The fuel pressure regulator limits the fuel pressure to what the engine actually needs, based on vacuum, and bypasses the rest (about 95% of the fuel pumped) back to the fuel tank. The fuel being pumped is what actually keep the pump cool. Also one of the reasons why a L-tronic never vapor locks.

So in a pinch, you could use a different fuel pump in the system. I guess.

A carb fuel pump stock puts out about 2-5 psi and generally has no regulator and doens't need one (unless you are running with certain dual carbs that like to see fuel pressures of <3.5 psi). On the factory mechanical pump you adjust the pressure by 1) using more gaskets on the base or 2) grind down the push rod that does the actual fuel pumping. A number of people use a electric "rotary pump" that is generally regulated internally at about 3.5 psi.

Edited to correct for my lousy typing. Embarassed

MadFrankie · Posted: Wed Jun 13, 2012 2:38 pm Post subject:

That all really interesting as ive found a pump in GSF for £60 while heritage and the like are selling what looks like the same one at £250.

I did wonder if you could use a different pump from somewhere else but wouldn't know where to start as I've never had a bus with a FI system. It's a steep learning curve!

pgtips · Posted: Thu Jun 14, 2012 1:14 am Post subject:

FI is not too bad, different to my carb set up and with both being side by side I'd choose FI all day long. It is actually pretty straight forward once you get your head around it. (trust me, it blew me for a while but its quite clever when you realise although I still learn - re Q at end of this post !!)

As Randy correctly said, pressures are different between carb and FI (which i didn't make clear). I have ground my mechanical pump rod to get the right pressure for my carbs but I will still use a regulator for peace of mind, something like a malpassi/filter king/ sytec etc.

But back to FI, please share your experience with the pump, this was always a grey area to me but it seems a reasonably decent pump and a working right regulator (which you could buy an adjustable one) makes the options wider and lets be honest, £60 or £250 to do the same job is huge.

I never realised how inefficient it all is, up to 95% of fuel returned sort of begs the Q why so much but I guess thats needed to keep pressure high for the injectors.

I do have one more Q. the regulator looks to me like its on the fuel return back out the system but I would have expected to find it on the way in, i.e between pump output and fuel rail to injectors. I must have missed something there so bentley out time.

Cheers,
PG

germansupplyscott · Posted: Thu Jun 14, 2012 6:52 am Post subject:

the regulator is like a dam at the end of the fuel river. the dam (regulator) has a leak in it, the size of the leak determines the pressure the regulator is holding. it's slightly variable with vacuum so that pressure is higher under load, this makes a richer mixture. the leak in the dam returns fuel to the tank. if the regulator was at the pressure side of the loop the pressure would be dropping all the way along as the injectors stole fuel from the loop. with the regulator at the end of the loop a constant pressure is possible since there is always more fuel than is required and most of it is returning to the tank through the controlled leak.
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pgtips · Posted: Thu Jun 14, 2012 7:50 am Post subject:

what a excellent analogy Scott (acts like a dam), perfectly clear and another thing I have learnt/understood... which again makes sense. Maintaining the pressure behind it !!

Very Happy

dabble · Posted: Mon Jun 18, 2012 12:09 pm Post subject:

Hi guys - I am having a problem with my 78 2.0 FI:

I replaced the plugs, wires, cap, and rotor. I set my idle at 1k rpm, and my timing is in spec at 7.5*btdc and 28* btdc 3500rpm.

My problem is this:
I have a sputter/pop/backfire when I let off of the accelerator. It does not make this sound when I am on the throttle. It does not sputter/pop/backfire as much when I am stationary and press the throttle. The sound goes away immediately when I depress the clutch.

I've checked for vacuum leaks and I can't find any. Thoughts? Decel valve need to be replaced?

Thanks!
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I Need Help with L-Jet / AFC Fuel Injection Topic
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