I'm trouble shooting a fuel issue on my 87GT. I've done some trouble shooting and all indications point towards a bad fuel pump. Here's a rundown on what i've done so far. My car has been sitting for about 8 months without running. New battery and checked fluids and tried to crank it. It fired up instantly for about 5 seconds then died. I tested the shrader valve and nothing. Not even a dribble. When i turn the key, i don't hear the fuel pump prime up or the relay click. I thought it was possibly the relay since there was no click after two seconds. Since i have another 87GT (no engine) so i swapped the relay. Still no click from the relay. I jumped the ALDL and didn't hear the pump running. I guess my question is, if the pump is bad, should i still hear the relay click? I'm almost certain it is the pump but just wanted to get opinions before dropping the tank. Thanks
[This message has been edited by labbe001 (edited 06-20-2012).]
The ECM turns on the FP Relay - so if you don't hear the relay click on, the next question is "Is the ECM running?"
So with the key on engine off - does the SES (Service Engine Soon) light come on? It should.
If it is not first thing to check is to see if the ECM reset connector got left unplugged. If it is unplugged that will leave the ECM with no power.
well i took out the instrument cluster while i'm restoring the interior....so i am unable to check the SES light
i checked all my connections and all is well with them....is there any other way to check if the ECM is running? By jumping the ALDL connector, should i hear my fuel pump running regardless of a possible bad relay or the ecm not running? cause i don't hear it......
well i took out the instrument cluster while i'm restoring the interior....so i am unable to check the SES light
i checked all my connections and all is well with them....is there any other way to check if the ECM is running?
Check for the SES light at the ECM. Connect your test light to power (cig lighter for example) and then probe the connector at the brown/white wire at A5 (2.8)
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By jumping the ALDL connector, should i hear my fuel pump running regardless of a possible bad relay or the ecm not running? cause i don't hear it......
Yes the fuel pump should run with this test. No however the test junpers right to the pump so it won't activate the fuel pump relay.
ok so weird thing going on now....i jumped from the batttery to the b terminal on the fuel pump relay and nothing......after doing everything i came to the conclusion that i was going to replace the fuel pump.....i replaced the pump and i finally have fuel preasure (about 45)...fuel shoots out of the shrader valve when i push it as well .....now the car starts up and immediately dies.....if i keep trying to crank it, it wont start.....if i let it set for about 30 seconds, it will fire up the immediately die....i checked my fire and i'm getting fire....however, i'm still not hearing the fuel pump relay click....how would i be getting fuel pressure and the relay not work? any thoughts would be greatly appreciated
Bump to acknowledge I gave phoneawgz a plus. The answer in his first post helped me track down a faulty fuse in the ecm reset connector that had me stumped on my swapped car for a few nights.
Pump was fine after tests but the relay was not clicking and the pump was not priming (intermittent at first not at all on day 2). I had checked this ecm reset connection before and checked the fuse in it (custom swap harness with different connector) and it seemed fine. Swapped the fuse in the ecm reset as a result of this post and the car fired right up.
Final problem was that water had gotten into the aftermarket connector a corroded the fuse. Fuse looked fine at first exam. It was obviously not.
Thanks again to those that post helpful answers like this.
I know this is an old thread, but I'm hoping someone will see this bump.
I've got an 84 and am having the same issues, power is getting all the way up to the fuse box under the driverside dash for the ecm, will run on the oil pressure relay once there's oil pressure, but there's no check engine and im wondering how you go about replacing the fuse in the fusable link? I'm semi certain ive located it as its in a slightly different spot on the 84 but not sure if there's a fuse there?
The wire is the fuse. 84s had fusable links at the starter. If your fuel pump is not running with the key on, you should check the relay...(on the firewall behind the driver seat).
[This message has been edited by Gall757 (edited 10-15-2018).]
Gall757 even if the CEL isn't coming on with key on engine off? I keep hearing that the ECM could have gotten fried but it seems unlikely since it hasn't had the cables swapped. I'll have to further check the fusible links cause they're tucked up under the intake and I couldn't really get to them before dark.
Yeah kinda tucked down there, hard to reach a bit and i didn't have a ton of time today to look around. Ill try to test for voltage at the relay connection (green/ white) to make sure its getting power the first couple seconds after turning on.
