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Thu Jul 12, 2012 10:08 am

I have a 1982 vw vanagon westy. It was originally a diesel. now has a 1.8 l SOHC Jetta motor in it (87 i think). when driving at speed any right hand bend in the road makes the engine stall. once straight the motor has power again. the fuel line does come out of the right side of the back of the tank. But it cant have always been like this. And it does get more prominent as the tank gets more empty.

i originally thought it was an electrical short some where. I went through most of the harness and checked for cracks or other places to short. I haven't checked any of the wires outside of the engine bay. but i am starting to think it is fuel related.

I am about to go hook up a fuel pressure gauge and have my buddy drive it while i watch it..

Any thoughts or inputs appreciated.

shaggy

Thu Jul 12, 2012 11:13 am

Interesting. I notice my fuel gage responds to turns and hills due to its location at the left front of the tank (needle points higher on right turns and downhills, lower on left turns and uphills). Maybe your gas outlet is doing something similar and some compounding factor is causing the engine to starve for fuel.

I would check to make sure you don't have a major tank rust problem (fairly common). Pull the gas pump and filter and check to see if there is a bunch of rust plugging them up.

It may also be electrical, maybe a loose wire that just barely makes its connection until you turn, then it leans away from the connection? Do you ever hear your fuel pump buzzing and does it do that all the time or does it cut out when you turn?

Thu Jul 12, 2012 11:25 am

so i hooked up a fuel pressure gauge and drove around. definitely drops from 80 to 50 or lower on downhill breaking and right hand turns.

In the bentley manual it shows the fuel filter before the fuel pump. mine is in the engine compartment. Could the fuel filter act a a reservoir in these turning situations? maybe a reservoir in between the tank and pump is necessary. What a efed up design. very frustrating

Thu Jul 12, 2012 12:14 pm

sanjuanbum wrote: What a efed up design. very frustrating

To be fair, your converted van is not how it was designed from VW.

If your pump is pushing fuel at the right pressure all the time a reservoir wouldn't be needed. I would focus on figuring out the cause of the pressure loss instead of trying to treat the symptom. Where did you install the pressure gage at - is it reading pressure just downstream of the pump or are there other things that could cause the pressure loss between your gage and the pump)?

Thu Jul 12, 2012 12:15 pm

does it happen when the tank is full?

Thu Jul 12, 2012 12:15 pm

does it happen when the tank is full?

Thu Jul 12, 2012 12:22 pm

no it gets worse as the tank empties.

I installed the gauge in between the filter and the banjo fitting on the airbox(or the digi fuel distribution block).

Thu Jul 12, 2012 12:38 pm

sanjuanbum wrote:

I installed the gauge in between the filter and the banjo fitting on the airbox(or the digi fuel distribution block).

You're running CIS-E or Digifant?

Thu Jul 12, 2012 12:52 pm

and yes mine is'nt the original design but the original design that is in the book is flawed in my opinion. why not have the pick up in the center of the fuel tank.

but that post wasn't that clear on re read. There was a fuel filter inline between the pump and tank in the original design. I was wondering if that fuel filter did act as a reservoir for when the fuel in the tank sloshed around. This would be why i'm running into this problem.

it is a CIS. No E

Thoughts?

Thu Jul 12, 2012 1:22 pm

sanjuanbum wrote: and yes mine is'nt the original design but the original design that is in the book is flawed in my opinion. why not have the pick up in the center of the fuel tank.

but that post wasn't that clear on re read. There was a fuel filter inline between the pump and tank in the original design. I was wondering if that fuel filter did act as a reservoir for when the fuel in the tank sloshed around. This would be why i'm running into this problem.

it is a CIS. No E

Thoughts?

The pickup is in the center of the tank, but the outlet just happens to be off to one side. You may have some kind of internal failure in the tank that is causing your problems or maybe something is floating around in there that blocks the pickup on hard turns and while braking.

On later Vanagons and on most all of their other fuel injected rig, VW used a canister filter after the pump.

Thu Jul 12, 2012 1:27 pm

Knowing it's CIS may help other posters with suggestions.

IIRC, the Vanagon pump by itself puts out a constant 100 PSI or so. CIS requires a much higher fuel pressure than Digifant. (hence the steel braided lines).

My guess is that regardless if CIS or Digi, specs in Bentley or Hayens should show fuel pressure specs when engine running and residual pressure etc. If you don't have those, check this out:

http://www.race.nangreaves.com/golf/FU01/ch5.5.html

If you look through "contents" you should be able to find even more info on CIS.

Neil.

Thu Jul 12, 2012 1:44 pm

I used to have a 1.8 conversion with CIS. Although I never had this problem the new owner let me know that she was having intermittent stalling. Her mechanic fixed it and supposedly the problem was the fuel distributer was not level. They built something to prop it up level and now it's fine.

Thu Jul 12, 2012 2:02 pm

Vanagon Nut wrote: ...

My guess is that regardless if CIS or Digi, specs in Bentley or Hayens should show fuel pressure specs when engine running and residual pressure etc. If you don't have those, check this out:

http://www.race.nangreaves.com/golf/FU01/ch5.5.html

If you look through "contents" you should be able to find even more info on CIS.

Neil.

And I should have noted that I wasn't necessarily pointing to fuel pressure as a problem. Regardless, there seems to be good info on the CIS system in that website.

Neil.

Thu Jul 12, 2012 3:38 pm

Do you have a fuel accumulator in line after your fuel pump? This was how CIS cars came from the factory. The accumulator is a spring loaded diaphragm. It was designed to improve hot starting, but it also helps to prevent surges or drops in fuel pressure, which CIS is very sensitive to. They are not to difficult to add if you don't have one.

Fuel Pressure. I don't have my manual in front of me. But Waterboxer engines (I think) had between 35-40ish PSI pressure. CIS I believe is usually around 60+PSI. Any variance from this will cause running issues.

As mentioned above there is a fuel pickup in the center of the tank with a metal line running to the fuel outlet fitting. If this line or the pickup has become cracked or damaged the pump can pull air. New tanks aren't very expensive last I checked. Its a long job, but a tank swap isn't mechanically complicated.

For those wondering the website below indicates that a Digifant/jet fuel pump doesn't make enough pressure/volume for a CIS setup. Not sure if that applies to the vanagon fuel pump.

http://www.cabby-info.com/fuel.htm

My Van originally came with a similar setup to yours. I have just finished moving over to digifant.

Hope this helps.

Thu Jul 12, 2012 4:11 pm

It just occurred to me that I have experienced the issue the OP describes when my van was 1.8L CIS-L.

When going up steep hills with about 5 gallons of fuel in the tank the engine would appear to lean out. I assumed it was the altitude (around 8k feet) but now that I think about it, it happened at lower altitudes too.

My van had a CIS pump and accumulator. However, in stock form there was usually a lift pump located in the tank (for CIS cars). I have read of instances where a failed lift pump causes poor CIS performance. The vanagon has no lift pump, I assumed that the tank design didn't warrant one, but maybe I assumed wrong?
:?

As for adding a simple reservoir to the fuel system (Such as a filter) I don't think it would help in this case, as any vapor in the fuel system with adversely effect the way CIS meters its fuel. It relies on the flow rate of fuel through various small orifices.

I am a bit foggy on the details, but some CIS cars had a type of vapor trap/accumulator interior to the tank where the fuel pump mounted. The lift pump put fuel into this smaller "tank" and had a vapor return to the main tank.

Edit: Found the external reservoir thingy
http://www.race.nangreaves.com/golf/FU01/ch4.html

Fri Jul 13, 2012 4:03 pm

SOOO!! took the tank out. Someone (probably the guy that did the motor swap) made their own nipple on the gas tank that is not hooked to the internal tube. This would probably be the culprit 8)

This nipple is larger than the original.. Is there going to be enough quantity of of fuel on the original nipple to run a CIS? it seems to there would be but why would someone go through the trouble of welding a nipple on a gas tank for no reason?

Thoughts, Ideas are Appreciated!!!! :wink:

Fri Jul 13, 2012 4:31 pm

sanjuanbum wrote: SOOO!! took the tank out. Someone (probably the guy that did the motor swap) made their own nipple on the gas tank that is not hooked to the internal tube. This would probably be the culprit 8)

This nipple is larger than the original.. Is there going to be enough quantity of of fuel on the original nipple to run a CIS? it seems to there would be but why would someone go through the trouble of welding a nipple on a gas tank for no reason?

Thoughts, Ideas are Appreciated!!!! :wink:

Don't know much about the Diesel tank but the original gasoline tank was an engineering blunder in that the outlet was too small and caused cavitation problems. VW corrected this for the 1986 model, but it looks like your PO tried to do it his own way.

Fri Jul 13, 2012 4:44 pm

is this engineering blunder fixed in aftermarket tanks? or can I buy one for an 86 or newer?

Fri Jul 13, 2012 10:23 pm

just a little bump. would like to know weather to order a gas tank or not.

Fri Jul 13, 2012 11:50 pm

sanjuanbum wrote: just a little bump. would like to know weather to order a gas tank or not.

If you're certain that the outlet pipe installed or modified by a PO is not connected to the internal tube, then you likely know the answer. I would figure that having a weldor-fabricator repair that hack wouldn't be worth it. That said, I have to wonder if the new nipple is just welded over top of the OEM nipple to allow a single size ID hose between the nipple and fuel pump inlet. This may also have been done to eliminate the pre pump square filter and just use a post pump filter as some Vanagons do. But as you say, the new nipple is not connected to the internal pickup tube.

I am not familiar with the Mk1 or Mk2 that used CIS, but if you are sure of what model year to look at, check a bone yard and measure the fuel tank outlet nipple. This may lead you to what type of gas tank to get.

I was curious about fill pipes. Seems your diesel may have the smaller OD type. A link to Busdepot's 50 mm fill neck:

http://www.busdepot.com/251201121d

If you have that style of fill neck, that's good as it *should* work with the newere style gas fuel tank.

Double check this though.

Neil.