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Jeff S.S.
Jeff S.S., VW Mechanic
Category: VW
Satisfied Customers: 51
Experience:  30 years ASE Master Certified Auto Tech- Owner of Audiwerks
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1981 VW Rabbit Pickup: fuel pressure..the vibration..fuel filter

Resolved Question:

I have a 1981 VW Rabbit Pickup gas . first of all the fuel pressure acumulator started to leak fuel, so Ii replaced it.Then it made a viberating humming noise and you could feel the vibration at the inlet side of the fuel filter. About a month after I replaced the acumulator the pickup would start to jerk while driving down the road. if you pressed on the gas it would get worse.I thought the fuel lines might be freezing up so I put in gas dryer and injector   cleaner in the tank. This did not help. I read in my manual to do a quick test on the injectors. So I pulled one out at a time ran the fuel pump and noticed as I went through the injectors that fuel would come out for a few seconds and stop. I could hear the pump still running I was still raising and lowering the sensor plate.If i left the sensor plate down for a few seconds it would start flowing fuel out again.I put a new fuel filter on,the fuel distributor is new,the fuel pump is new and it still jerks when trying to accelerate
Submitted: 8 years ago.
Category: VW
Expert:  Jeff S.S. replied 8 years ago.


Do you jump the fuel pump relay with a jumper wire while doing the injector test?

Usually, the test is done with all 4 injectors removed and placed on a towel. Jumper the pump and then raise the sensor plate. Do your injectors spray for a few seconds then stop?



Customer: replied 8 years ago.
Yes.But I used a container.#1 & #2 injector stoped spraying after a few seconds.On #3 & #4 injector I could put my finger on each of them lightly and stop the flow on them.I kept the test running for about 2 min. #1 & #2 never sprayed again.I replaced the fuel pump,ran the test again,all injectors sprayed very well.
Expert:  Jeff S.S. replied 8 years ago.


Let me know if the test drive goes well.


Customer: replied 8 years ago.
Once the engine is good and warm and you press on the accelerator the pickup starts jerking again.
Expert:  Jeff S.S. replied 8 years ago.

Hi Ironman

If the injectors a spraying correctly and the sensor plate moves smoothly up and down, have you checked for vacuum leaks?

Does it idle normally? Does it jerk when you try to accelerate gently?



Customer: replied 8 years ago.
I can not find any vacuum leaks. Idles Great. Revs up great. 1st gear is good,2nd gear as rpm's raise starts to jerk a little.3rd gear jerks harder as I accelerate and so on.
Expert:  Jeff S.S. replied 8 years ago.

Back againCustomerfor one last shot at this.

If I were you, I'd get a coffee can, pull all four injectors again, jumper the fuel pump, put out my cigarette and pull the sensor plate all the way up and watch them spray for about 10-12 seconds. They should make a high pitched squealing sound and really flow a nice cone shaped pattern. If this is the case, I give up. If it isn't the case, I would tend to blame the fuel pump or some kind of blokage



Customer: replied 8 years ago.
I am checking for blokage.I did another injector test.# XXXXX & # XXXXX were not spraying well.So I Removed the gas tank.Found that the filter in the tank had come out from where it should be.
There was a was a rubber piece in the bottom of the tank under were the tank filter should have been.The rubber piece seemed loose,So I started to remove it.The rubber just fell apart.
Cleaned the tank out.Put the tank filter back where it should have been.Pulled the pump off.
I wiil Have to get new injectors,and clean out the fuel lines,and clean the fuel distributer.
Is there anything else you can think of?
Expert:  Jeff S.S. replied 8 years ago.

Now I know why you go by the name Ironman!

You didn't mention a new fuel filter (the one in the engine compartment), and thats the first and cheapest place to start. That filter is designed to protect all of the components downstream from it from contamination. When you remove the old one drain the intake end of it into a glass jar to see what kind of crud you may be dealing with. After disconnecting the fuel lines from it, loosen the clamp and slide it out carefully without tipping in order to reain as much fuel in it until you can tip it into the jar.

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