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rsrmike rsrmike is offline
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Join Date: Jan 2008
Location: Birmingham, AL
Posts: 538
OK, sorry buddy, I haven't forgot about you. I've managed to confuse myself after reading back through what we've said. Given that you said the fuel pumps run all the time with the key, the overboost switch still kills the fuel pumps, and the fuel pumps run even with the control unit in question unplugged could only mean one thing to me. I would bet someone bypassed your fuel pump relay circuit out of the loop of this control unit. Which doesn't make sense that it acts up when the control unit starts clicking.

Are you positive your losing the fuel pumps when the car acts up? When I removed this control unit from the 91 that started this crazy thread, I just connected the white wire from the over boost switch to the brown and yellow wire that grounded the trigger side of the fuel pump relay at the connector for this control unit. I had to do some other hacks as well to cover the other functions of the control unit. As I said before, I wasn't proud of it, I was just told to "make it work" and "don't F-up the coilpacks" so I did what I could with what I knew.

I would suggest some testing first to determine for sure what is shutting down. And for sure if the fuel pumps do in fact work like we think they do on your car. I guess you're aware there is a valve that buzzes in the engine that sounds kinda like a fuel pump to some, just in case. I would try to hook a test light of some sort either directly to one of the fuel pumps, or to the output side of the fuel pump relay to see if they are indeed losing power when the car runs bad. You could also use a fuel pressure gauge, but that's fairly involved in your case.

Given the odd chance someone wired yours like I did, or if the fuel pumps are still run through the control unit, another possibility would be if the wires for the overboost switch and the gauge sending unit were crossed. The gauge sending unit can sometimes provide enough of a ground off boost to ground some relays and then lose continuity as the boost builds. Is the white wire connected to your overboost switch? I did this on an '87 w/ a Kokeln one time in the early years... I don't think the gauge goes through this control unit though so who knows.

I hope I'm not just confusing you more. I would learn more about what's been rewired and how and start there if I were you. Good luck, let me know what you think.
Old 02-29-2008, 07:45 PM
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