# 1990 Jetta GL 1.8, 8v won't start



## pdxs3t (Feb 11, 2010)

1990 Jetta GL 1.8, 8v won't start. Was driving it at highway speeds and lost power and then the vehicle just died. Motor turns over, has good blue spark and both fuel pumps are working as they should (performed flow test and both are great). I've replaced the relay, spark plugs, cap and rotor. The motor act's like its not getting fuel? I'm very new to VW's and I'm at a loss on what the problem could be. What I am reading in the manual, in the trouble shooting section points me to the ECU. Very unsure and thought I would ask here and maybe get some help? Does any one know which ECU fit's this year of Jetta?
Thanks in advance!


_Modified by pdxs3t at 6:11 PM 2-27-2010_


----------



## Fat Rabbit (Nov 18, 2001)

*Re: 1990 Jetta GL 1.8, 8v won't start (pdxs3t)*

The fuel injectors operate electrically by grounding through the ECU.
It is quite possible that your ECU burned out. First thing to do is to check the ECU ground which should be attached to the lower stud on the hose flange at the transmission end of the cylinder head. There should be several brown or black wires that attach there. Check to see that they are still connected. You can test the ECU operation with a 12V LED test light across the fuel rail connection. Have a friend try to start the car while you observe the test light. It should flicker rapidly. If you get no response reverse the test leads on the electriac connection and try again. No response -- either way means that the ECU is not pulsing the injectors. Make real sure that the ground connections mentioned above are good or even a different ECU will burn out.
One other possibility is that the Digifant Control Unit relay is bad. That relay is in position 3 from the left, second relay row above the fuses on the fuse and relay panel. That relay supplies power to pin 14 on the control unit connector.
As for the ECU -- check the PN that is on the unit in the car. Most of the Digifant II units have the same main PN with the last two letters being variable. I have always tried to replace ECU's with the same PN -- ie. the last two letters. But any Digifant II ECU with same main PN and the correct number of pins for the connector should run the car. FR


----------



## pdxs3t (Feb 11, 2010)

*Re: 1990 Jetta GL 1.8, 8v won't start (Fat Rabbit)*

Thank you!


----------



## pdxs3t (Feb 11, 2010)

*Re: 1990 Jetta GL 1.8, 8v won't start (Fat Rabbit)*

FR,
I'm at a total loss now...
ECU ground is good, tested ECU using an LED, light flickered. Going to assume since I had a positive response with the LED, the relay is good too.
Motor turns over and still act's as if it is starved for fuel.
Could the Fuel Pressure Regulator be coming into play at all? 
Thanks again for your tips, very helpful.
-JC


----------



## edub122 (Mar 17, 2010)

*Re: 1990 Jetta GL 1.8, 8v won't start (pdxs3t)*

Is your engine flooding? Or do you smell gas? The engine just shut off, its never happened before?


----------



## pdxs3t (Feb 11, 2010)

*Re: 1990 Jetta GL 1.8, 8v won't start (edub122)*

No, engine is not flooding. Not smelling gas either. I performed a flow test and it checked out ok. One would think that the engine would be flooded but its not.
I was traveling at highway speed and then started to loose power until the car came to a rolling stop. Never happened before and haven't been able to get it started since.
Replaced plugs, cap/rotor, fuel pump relay, swapped out ECU with a known good one. Tested both ECU with LED meter, have good spark to all cylinder's and the injector's tested within spec.
Motor turns over just fine...
Only thing left that I know what to do is a match and a can of lighter fluid....


----------



## ziddey (Apr 16, 2006)

*Re: 1990 Jetta GL 1.8, 8v won't start (pdxs3t)*

pumps work but you're not getting fuel to the injectors.
crack the fuel line at the rail and see if fuel comes out.
how's your fuel filter?
car starts on starter fluid?


----------



## pdxs3t (Feb 11, 2010)

*Re: 1990 Jetta GL 1.8, 8v won't start (ziddey)*

Yep, fuel does come out at the rail. That is where I performed 1 of the 2 flow test's.
Fuel filter is brand new too. Nope, car won't start on starter fluid.


----------



## TheMajic86GTI (Aug 9, 2009)

*Re: 1990 Jetta GL 1.8, 8v won't start (pdxs3t)*

mAybe check ur timing...Belt might hav jumped...


----------



## pdxs3t (Feb 11, 2010)

*Re: 1990 Jetta GL 1.8, 8v won't start (TheMajic86GTI)*

Checked the timming belt to this afternoon. It on and tight.
Thanks for your reply!


----------



## kfleal04 (Mar 20, 2010)

hey I own a 1990 VW Jetta 1.8 8V. i had the same issue and it turned out to be the catalytic converter. have you checked that out yet????


----------

