1,9 WBX dies when I put full gas

[Fojes]

Hello,

I have a problem on my vanagon 1,9 DH Digijet with electronic injection.

Problem
When i ride and i put a full gas (for example in 2000 rpm) engine dies inmediately. If i put my leg out of the gas pedal, it runs again. Sometimes it happens, that breakdown is very short, it lasts less then second, but mostly its dead until i put my leg out. If i am ride very gently, everything its ok, but riding to hill is an big issue. With the engine cold is it much better.

What i check or replace
- I cheched temperature sensor and replace him
- Ignition timing is correct
- During breakdown ignition working (testing during ride with stroboskope... but maybe it can be completely incorrect at the moment?)
- I change ignition timing unit, tried put there another distributor
- Throttle position switch works good, i tried to unconnect it and i tried to switching it manualy in cabine during ride
- I change relay of fuel pump and i checked the fuel pressure (2 and 2,5 bar)
- I tried checked fuel pressure during breakdown (college checked it on barometer, still good (2,5 bar)
- I put fuel filter out
- I change air flow meter sensor

If you have any ideas, i wiil be very gratefull because a dont know what i have to do next. We are with my wife on trip to Norway and izs very anoying... so i dont have now all tools and gadget, but if it will be possible, i will try to test it.

Thanks so much!

[dabaron]

is this an automatic or manual transmission?
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1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo

BiWerks Design, LLC

[Fojes]

It is manual transmission.

[MarkWard]

Can you crimp the hose from the pressure regulator to the tank? This should increase fuel pressure and richen the mixture. Drive and see if power is improved. Fuel pressure is only one measure. You need volume for power and should measure volume. If driving improves even a little, it’s probably a fuel problem and you know where to start looking.
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[Vanagon Nut]

[Fojes]

Ok, if will be possible, i will try it during the day. And you think crimpt it completely or just a little bit?

Yes, i am sorry i forgoten to write it, RPM does not drop down, so it seems thats the problem is not in ignition switch, because if i turn off by key, RPM drops down.

Thanks!

[Vanagon Nut]

[Fojes]

[MarkWard]

Partially restricted would work. Just trying to make it simple. I’d suggest disconnecting the oxygen sensor while you are trying to figure this out. It could be hiding the problem.
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[Vanagon Nut]

[jlrftype7]

[Fojes]

So i try to crimped hose from pressure regulator to tank and the problem dissapeared! I drove only small distance, because of smell of gasoline (i was afraid about pressure in hoses), but it rode really good.

I am really happy, that i know something new, so thanks so much for this advice. So it look like a problem with fuel pump, fuel pressure regulator or fuel lining. But i dont understant, how it can happen, when pressure during ride is good, its about amount of fuel? Maybe clog fuel lining or tank?

[Vanagon Nut]

[4Gears4Tires]

[crazyvwvanman]

You should do a fuel delivery rate test such as called for by VW.
This measures how MUCH fuel is being pumped, hopefully while the pressure stays within spec.
So with a pressure test gauge connected, unhook the return hose from the regulator and connect a piece of hose from it to an empty container at least 1 liter in size.
Then jumper the fuel pump ON for 30 seconds exactly while watching the gauge.
Measure how much fuel was pumped into the container.
The rate should be at least 1000cc per minute or 500cc per 30 seconds.

Bentley page 20.29 has this procedure, without the test gauge that is helpful IMHO.
Also same on page 20.19 for Digijet.

Mark

[MarkWard]

Hey, blind squirrels find nuts occasionally. At least you have a place to start looking now. Glad to help. Might need a place to store a van in Europe someday. You build the world you live in.
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[Fojes]

Thank you all for your advices! A tried a few thinks, fuel delivery test, that was ok - 0,5l per 18s. I inspect vacuum hoses and they looks good. Same witch the pressure regulator. But i figured out, that i am loosing fuel pressure few seconds after turn pump off. A clamp hose from pressure regular, but it was the same. When i was clamp hose from pump immediately after pumping, pressure stay in the system. So it looks to some problem with fuel pump i think. I will try to look for another and test it.

[jlrftype7]

[MarkWard]

Based on your fuel pressure readings, I suspect the fuel supply volume is likely ok. When you up the system pressure, the injectors spray more fuel per pulse. That would be an any pulse duty cycle.

If the engine seems to idle smoothly and other than the fuel starvation under load, I would suspect the actual injectors are not flowing to spec. Problem is trying to measure their flow when you are on the road.

It might be worth just finishing your road trip with the return restricted and drivability restored. The worst symptom would probably be poorer fuel mileage.

When you get home, you can tackle checking the injectors or just sending them out for service. The fuel volume test on the system is fairly straightforward, but if you have the family and the van packed, probably not worth it at this point.

Safe Travels.
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[Fojes]