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Matt, Engineer
Category: VW
Satisfied Customers: 21707
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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I have a 1979 vw beetle. There is no power on acceleration.

Customer Question

I have a 1979 vw beetle. There is no power on acceleration. Changed fuel filter and all 4 injectors and car ran good for a few miles. Checked fuel pressure and relieved exhaust. Changed relay and head temp sensor with new parts. Changed harness, Ecm, and maf sensor with tested used parts. Changed electric fuel pump and ran new fuel line from pump to engine. Air intake hose has no cracks. Egr works fine. Injectors seem to have inconsistent flow, but noid looks good. Car ran good twice for a short time, both times after removing and installing injectors. There are no fuel leaks. Run out of ideas.
Submitted: 1 year ago.
Category: VW
Expert:  Matt replied 1 year ago.


are you sure that this is a 1979 car? as fuel injection on the old air cooled beetle wasn't introduced until 1986?

Customer: replied 1 year ago.
1974 was first year. type 1 and type 2.
Expert:  Matt replied 1 year ago.


in that case I'd check that throttle is opening fully and if that's OK then I'd check over the state of the injector wiring harness as it sounds like that you may have 1 or more injectors with a broken wire - this can be checked with a 'noid' light

and disconnect the loom on all 4 and trace it back checking for hard or damaged sections and corroded joints

if you can't find any issues then I'd use a meter to check the resistance / continuity between the injector plug and ECU plug

Customer: replied 1 year ago.
has noid and harness has been changed.l if I add external fuel it has throttle response
Expert:  Matt replied 1 year ago.


thanks for the extra information

so its definitely fuel related as it responds with external fuel

but you've replaced the harness, ECM and the injectors?

and it has the correct fuel pressure?

can I ask what figure you saw for fuel pressure?

Customer: replied 1 year ago.
32 psi.
Expert:  Matt replied 1 year ago.


OK with the engine idling and the vacuum pipe connected you should have at least 30 psi so thats OK too

I would say the next thing to try is check that you're getting the 12V on the ECM fuse and check that the engine earth connections are clean and tight as there should be a couple and the small wire type that are secured onto the engine with ring terminals are the ones for the ECU

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