1.6 ME strange fuel problems

[QuantumDave]

OK Gang,

It's good to be back here posting again even though I haven't done so in a while. At 366K on a 91 Jetta N/A I've got a strange problem I'd like to put before you all. I have clear fuel hoses going into and out of the filter and on either side of the return "T". Things I did recently: replaced filter, installed dipaco non return valve out back by water trap(factory original was junk), replaced rubber hoses that transition from pex to water trap, replaced rubber transision hoses immediately off sender. Whenever I replaced hoses I used high grade spring claps sized properly, applied a little grease to the barb and in case when I had to use a screw type clamp I used a small piece of rubber hose between the clamp and the hose I wanted to seal.

OK, here's the problem, I have a small amount of air bubbles present, which doesn't concern me- I've NEVER been able to get the line clear of them for as long as I've owned the car (since 212K) I've come to terms that that is just how it is.

Anyway, while cranking lately it takes a LONG TIME for the engine to fire. I'll crank it for about 20 seconds before I even get the first kick out of it. After that it requires anywhere from another 20-30 seconds of cranking for the engine to run on it's own.

after a series of succssesive kicks, the engine will kind of run with the starter still driving the process, stumbling along the way until the stumbling smooths out and the engine is able to outrun the starter albeit slowly and come up to a shabby idle.

Battery is new as of last night and starter is new this past summer, cranking speed seems sufficient. On the mornings when I've needed 2-3 jump starts over the period of an hour when the engine shuts down, fuel coming out of the IP going to the "T" seems to speed up and the fuel going from the tank to the filter, sucks back toward the tank. Keep in mind I have a new non-return valve that I tested prior to installing and is installed in the correct direction. When I installed it, it is orientated almost verticle but when I tested it, it functioned regardless of orientation.

The car can be running fine for an hour and as soon as the idle slows down to the point it stalls, if you crank it immediately to restart, it still takes 20-30 seconds of cranking to get it to start and it starts the same way, slowly stubbling back alive. I though a vacuum was present in the tank, but it still does it when I have the filler cap off.

It seems the IP has to fight for the fuel it gets. Any suggestions? I'll run a hose from the tank to the IP as I start to narrow it down, but this is getting so old it's not even funny. Sorry to say I have to rely of this everyday so I can't wait till my TDI is ready!!!

[QuantumDave]

Another thing, while out last night I had to rev the engine to keep it running at red lights, stop signs and when following slow traffic or it would stall out. I restarted it on several occasions by popping the clutch to save on the starter & battery. Never used to do that before. been hard to start for the past 2-3 weeks, makes no difference if the car is plugged in overnight or not.??

It's idling now as I type this- the morning start procedure takes between 1-3 hours before I can trust it on the road. I have the manual fan switch on & I don't mind leaving it running all night if I have to. Temperature isn't that bad 35 F degrees out- been that way for the last few days here in S. New Hampshire. Does go slightly below freezing at night.

[Quantum TD]

Check the fuel pickup in the tank for clogs

Remove your one-way check valve. Early Rabbits never had them. I doubt you really need one on cars with the same dang motor and pump.

Make sure you've got the hoses on the right side of the fuel filter. There's the Jesus clip part, but then 2 inlet and outlet tubes. Make sure those are right.

Finally, the vanes on your injection pump may be stuck. If that's the case, then your pump will have trouble drawing fuel from the tank.

[82vdub]

Like Quantum says, check for a blockage at the tank. That will cause fuel starvation after it's been running for a while. This could also be your hard starting situation. After running it for a while then parking it, the vacuum pulls the fuel out of the IP, then next am it's very hard to start.

Run the car from a bottle of fuel with a filter in the line directly to the IP. That will tell you if you have an IP problem or a fuel delivery problem.

[Fatmobile]

Sounds like fuel is being sucked back to the tank.
There is a vacuum developing,..
maybe the tank vent is clogged, remove the cap and see if that helps. Don't just remove it before you try to start it. Remove the cap before you shut it off.,..
maybe the pickup screen is clogged,.. you'll have to pull the fuel sender to find it, you'll probably need a vacuum cleaner to clean around it before you open the tank.


A vacuum gauge on your fuel line will tell you how hard the pump is pulling to get fuel.

[wild3bill]

I had just about the same problem on an 81 Pickup. sometimes the bubbles run the wrong direction, like vacuum in tank sucking fuel back. Someone suggested fuel supply problerm. I tried an electric fuel pump between the tank and the filter. Someone else suggested a rotary seal in the IP could be part of the problem. The suggestion someone gave me Rebuild the IP.Then I bought a 2003 TDi that absorbed all my time andCar money.Now I need to get back on the road. The electric fuel pump was a temporary install as power and mounting electric pump could be tricky. I remove the electric pump. for a while problem cured, then on the road random relapse.The guy who suggested rebuild IP probably right. I think VW added a "lift pump" to later Golf models.I think this started with "original IP". A vacuum gauge on the input to IP. If the IP don't suck it is bad

[Fatmobile]

A vacumm gauge on the front of the pump will almost always show 0.
Unless there is a fuel line restriction.

No lift pump was added to later models.

[wild3bill]

Idid not mean a vacuum gauge on a Tee. just a gauge on the input port of the injector pump.A year ago My 2003 suddenly died in the interstate me chanic said IP had no suction at all. I learned that a rebuilt IP for an older VW costs about the same as the core charge on a $2000 TDi IP ! ;-(

[Fatmobile]

Oh, I see,.. or think I do, ha.
There is no fuel line hooked up,
the gauge is hooked directly to the front of the pump
and read 0.

I've never seen a vane pump,
suddenly go bad and stop pulling fuel into the pump, but I don't know anything about TDI pumps.

From my experience it usually happens to pumps that have been sitting for awhile.

[QuantumDave]

Well, just thought I'd post an update for everyone else's information:

I solved the problem, now the Jetta runs just as good as it ever has and as a result, I'm keeping it.

What it ended up being was 2 small holes in the clear hose going into the IP. I couldn't see them because they were hiding under a screw clamp on the banjo fitting at the pump. I recently replaced every hose union with new hose & double opposed spring clamps & barb grease not too long before the trouble started with the exception of the only place on the system where I used a screw clamp just so I could undo it easier. I mean everything got done- hose from the top of the sender, stop at the water trap, on to the filter. If it was rubber, it got replaced.

Well with the heat, vibration and nature of hose that was not intended for fuel use, the underside of the screw cage on the clamp wore two holes into the hose- each hole was about 2mm in diameter-huge for a diesel system.

It had been good for a while, or so I though because I did it recently, but not as recent as the hose replacement campaign so I didn't question it. Thinking back, I have always had tiny air bubbles now I get nothing-just fuel. Using the screw clamp was no good from the start it seems.
And to top it off, I found it buy accident because it was in the way of loosening the forward IP bolt. I had the guage & pin thing going in a last ditch effort to improve starting.

Also, I replaced the sender for good measure with a used one in way better shape than my original. Other than a little wetness out of the throttle shaft bushing the fuel system is tighter than the James Brown Band!

Later