# MK2 Jetta CIS with ce2/obd2 VR Swap. Feul pump died? help troubleshoot please.



## stereosubstance (Apr 11, 2006)

I have a 1987 Jetta GLI (Wolfsburg), it used to have a ce1 cis 8v motor in it. About a year ago i swapped it for a ob2 VR6 out of a 96 passat, switch out the entire ce2 body and engine wiring harness, but kept the original fuel pump and tank setup on the car.

It has been driving fine, good power, nice and smooth. The other night I was driving along, stopped the car for about 2mins, got back in and nothing. It would turn over just fine but would not start. I have since replaced the fuel filter, checked the fuel pump relay and fuse and all is good. The car will start up, run for 2-14secs, slowly running rougher and rougher until it dies. Gassing it kills it almost instantly. I am almost %80 sure that the main fuel pump has gone out, as the pump used to make loads of notorious cis pump noise. Now when I can get it to start for a few secs, I hear nothing coming from the main pump, just a loud hum from the in tank pre-pump. I would rather not spend the $250 on a new pump until I am more certain that it is the problem. part time job

It has the 52mm main pump that fits into the surrounding fuel pump housing alongside the fuel accumulator and filter.

Any ideas? other things i try?


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## WaterWheels (Aug 14, 2005)

stereosubstance said:


> The car will start up, run for 2-14secs, slowly running rougher and rougher until it dies. Gassing it kills it almost instantly. I am almost %80 sure that the main fuel pump has gone out, as the pump used to make loads of notorious cis pump noise. Now when I can get it to start for a few secs, I hear nothing coming from the main pump, just a loud hum from the in tank pre-pump. I would rather not spend the $250 on a new pump until I am more certain that it is the problem.
> It has the 52mm main pump that fits into the surrounding fuel pump housing alongside the fuel accumulator and filter.


Seeing as the engine does not operate using CIS but an EFI system it does not require the high pressure the CIS pump produces (maybe this should be in the Motronic section too). I have my doubts about using CIS pumps to operate lower pressure electronic systems, forget about that regulator making it work right, but I doubt this is an issue with your problem. Because a bad CIS pump might still produce enough pressure to operate an EFI system, yes the pump could be bad. You would have to do a pressure test to be sure and if you do not already have the tester you might as well just replace the pump (cost about the same for a used pump). You do not have to, nor should you, buy another CIS pump. Look for a pump and housing from a Digifant II Golf or Jetta. It will bolt right up under the car like your current one, does not have the accumulator (you don't need it) and the connections can be made with clamps as it is lower pressure.


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## stereosubstance (Apr 11, 2006)

*rogger*

Thanks for the input. I was actually wondering if switching the fuel setup would work. My fear was that i would lose power at full throttle or high rpms. But that makes sense that i would be able to use the digi setup, those are way easy to find at the yard. 

Thanks


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