relay question

68Ghia · Post by **68Ghia** » Thu Jan 22, 2009 5:28 pm

OK; I found the relay(thx to all). I pulled the relay and tested it..OK...#30 female pin on the board has 12V. No voltage @ 86. Jump 30 to 87 and fuel pump cycles. Forgot if I checked 85 for grnd!!!!!! But I do have continuity between 85 & 86 (key off). It looks like 86 goes to 19 on the ECU and 85 goes to pins 16 & 24 on the ECU. If this is correct so far; if I check pin 19 on the ECU and find no voltage is the ECU kerplunck.

perrib · Post by **perrib** » Thu Jan 22, 2009 6:41 pm

I'm not sure on the 914 but with most european fuel injection systems the relay should close while the starter is cranking after it starts it needs to see an rpm signal to keep it closed. Some model will interrupt the power to the pump if the cranking time is excessive. If the point gap gets to small the relay does not stay closed after starting. Some systems incoporate the rpm moniter in the relay others use the ecm. If it is a four pronged relay it is controlled by the ecm. Either way the ecm or relay needs to see an rpm signal.

68Ghia · Post by **68Ghia** » Thu Jan 22, 2009 6:53 pm

I didn't think of that. I'll check fuel pump & circuit again w/ started engaged. Thanks a lot.

perrib · Post by **perrib** » Thu Jan 22, 2009 7:20 pm

It would be a good thing to do the ECM pinout test. Its the best test for the wiring harness integrity. Often you have a good sensor but resistance changes the reading by the time it gets to the ECM.

68Ghia · Post by **68Ghia** » Thu Jan 22, 2009 10:32 pm

OK, that sounds good. How do you do that test? I'm still in my first week of Porsche ownership here and this cruddy little Haynes manual is the pits. Is there a link where I can find this info?