Quote:
Originally Posted by donnj
need some help here, all is working but the 2 second relay for the fuel pump prime. With the key on its the pumps always on. I can hear the relay turn off and the green/white wire from the ECM shuts off after 2 secs, but the tan/white wire still has 12 volts. I swapped the relays and cant figure it out. i know, should have went with a Holley...
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Not going to be much help... But I do have a couple thoughts.
Are the relays sticking? My fan high speed motor relay sticks. Fixed via a whack with a flashlight.
My brother put in a switch for his fuel pump. Requires a lil hacking, and a lil more work to get it started, but his Fiero has one to manually turn on and off the fuel pump. Naturally gotta have it on to start it. But I don't think you want to do that.
I have an 88 myself, that is a running driving car (admittedly needs work but its saving my ass now...), love the low end torque of it, but I don't envy what you're dealing with. Electrical is black magic to me too. I do have a Factory Service Manual for the 88 TPI. Wouldn't hurt to take a look at it. The 2 second delay relay.....hmmm.
From GM service Manual
"FUEL PUMP RELAY
To control fuel pump operation, a fuel pump
relay is used.
When the ignition switch is turned to "RUN"
position, the fuel pump relay activates the electric fuel
pump for 1.5 to 2.0 seconds to prime the injector(s). If
the ECM does not receive reference pulses from the
distributor after this time, the ECM signals the relay
to turn off the fuel pump. The relay will once again
activate the fuel pump when the ECM receives
distributor reference pulses."
So you're saying its not turning off like it should correct? I'm looking at the flow charts for the pump relay circuit, most of them point to the relay. It may be worth it to pull the fuel relay when the car is running. Reason being. The oil pressure switch is tied into the same circuit as a back up. Get it up to temp. If you pull it and it quits, the OPS is bad. If it keeps running the whole circuit checks out.
The other thing that is throwing me off, is you say there is 12V to the black and tan wire. According to the wiring diagram there shouldn't be 12V on that wire. There is a black and pink wire as well as a dark green and white wire that should have 12V running through it, ditto for the orange ones. The Black and Tan wire is a fuel pump signal wire. Possible you have them mixed up?