Engine backfires


Asked by Dec 01, 2013 at 10:48 PM about the 1990 Volkswagen Vanagon Base Passenger Van

Question type: General

engine starts, idles and reeves okay for a  minute  but then after that, the throttle does not   
response when accelerating and it backfire and shuts engine off. Any suggestion what
causing it?

10 Answers

sounds like weak fuel pressure caused by the fuel pump relay not contacting reliably on account of weak system ground...wirebrush the connection to ground....be sure that there's 12.5 volts at the chassis ground so the relay will operate normally and provide power to the fuel pump reliably~

2 out of 2 people think this is helpful.
Best Answer

Thank you Roy. it would be my number one priority task and I will let you know the result.

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Hector Irizarry Duval

Could be low pressure also on the pump, check the ignition also and air leaks. Those are major causes for backfire. If it is a k jetronic injection system check and clean the plate it should move freely.


Fuel pressure and ignition checked okay. No it is not a kjetronic, but a digifant I. I just did what had Roy suggested but with no effect

12 volts at the relay? is the fuel pump relay any good? https://www.google.com/#q=1990+Volkswagen+Vanagon+fuel+pump+relay

1 out of 1 people think this is helpful.

think I've got it, it's the intake air temperature sensor~https://www.google.com/search? biw=1152&bih=624&tbm=shop&sclient=psy- ab&q=1990+Volkswagen+Vanagon+Intake+air+temp+sensor&oq=1990+ Volkswagen+Vanagon+Intake+air+temp+sensor&gs_l=serp.12...91693.96 533.0.98762. 1.32.psy-ab..21.0.0.KMtkU42bz9E&pbx=1

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this goodie replaces the manifold duct, diverter valve, heat riser and thermal choke and the two position choke~ if it's bad will act as you describe~

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Hector Irizarry Duval

could be the crankshaft sensor or the ignition module. you will need to try with another sensor or ignition module to test them.


Did you chk. All the air lines I know when my 1983 vanagon wont run right and starts to back fire that's always what it is ,one Time I could not see the air line it was hiding in there so I though that wasn't it ,two days later I found it hooked it up and it runs great now ,sounds like a air line to me ....

1 out of 1 people think this is helpful.
Hector Irizarry Duval

the digifant I has a mechanical MAF, you need to check if it is working correctly. they tend to get stuck sometimes giving the ecu false reading for causing the backfire also. and check for the air leaks like jamie said. keep posting...

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