86 528e no injector/fuelpump operation

Tiny
KUZIKOOD
  • MEMBER
  • 1986 BMW 528
Ok ive got an 86 528e that I got a steal on. It would start and run but had no power relized it was running soley off a leaking coldstart. The injectors were not firing and fuel pump would not run without a bipass wire in the fuse box. Fuel preassure is perfect(when bipassed) ive replaced every relay under the hood, the computer, cold start valve, fuel pumps, preasure regulator, everything I could find. Ignition works perfectly. Starts and runs off starting fluid but cant figure out why the fuelpump/injectors wont fire. Ive replaced computer from known running car. Studdied the wiring schematics and cant find anything ive missed. Only thing I havent replaced yet is this small green box mounted above the computer in the glove box that has a large heavy gauge red wire in it apearing to be inline hot for computer and engine harness. I tested at the relay to see if the computer was getting power and the answer is yes sort ofg I couldnt find how much voltage should be going to the computer but what it was actually getting was only about 3 volts. No clue why. Could that be the source of my problem.I bout it from a factory trained bmw tech/enthusiast. He couldnt figure it out either and gave up on it so he sold it to me for 200 bucks so its worth playing with. The only other question I had was would a bad/leaking oil pressure sending unit let the ignition fire but fuel system not? Any help wopuld be greatly apreciated cuz its my wifes car and she loves it and wants to drive it. If I cant figure it out im left with 2 options. Scrap it. Or remove the throttle body block off the hole mill out the top of the intake and slap on a two barrel carb put a hole in the hood and slap on a hood scoop. Please dont make me have to carb a beemer. Lol

tyvm, kuzi
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Tuesday, October 30th, 2007 AT 3:08 PM

5 Replies

Tiny
DR. HAGERTY
  • MEMBER
Remove the injectors and confirm their proper operation
I have seen plugged injectors do this
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Wednesday, October 31st, 2007 AT 2:26 PM
Tiny
KUZIKOOD
  • MEMBER
Ive checked the resistance value on the injectors/ wiring and it was what it should be. I know the fuel pumps not coming on and the injectors not firing have to be related some how. Everything I have read says that if I have proper spark I should have injector signal but have none
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Wednesday, October 31st, 2007 AT 8:42 PM
Tiny
DR. HAGERTY
  • MEMBER
Is there voltage at the fuel injectors with the key on?
You are correct in assuming that having spark should also
allow an injector signal and thats where the problem is.
If it runs when there is fuel present, then go to the
injector connector and back probe the red wire and see
if there is voltage(should be battery voltage 12.8V)
this comes through the main relay. The DME then
controls the injector pulse width by bringing the brown
wires down to ground for the amount of time the fuel is to be injected. The small green box is the idle control module. Look in the area above the DME and see if there is a black wire that is disconnected. It brings the DME the
signal from the coil.
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Thursday, November 1st, 2007 AT 9:54 AM
Tiny
KUZIKOOD
  • MEMBER
Thank you I will check that and post results the first of the week. And make a small donation as well

ty
kuzi
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Thursday, November 1st, 2007 AT 9:46 PM
Tiny
DR. HAGERTY
  • MEMBER
Keep in touch and we will get that car fixed!
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Friday, November 2nd, 2007 AT 10:58 AM

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