white91stang

i'm having a fuel pump problem and i traced it back to the relay.. here's what i have:

1. new fuel pump relay
2. 12v constant from pink wire from the starter solenoid
3. 12v coming from the red eec relay wire with key on (no voltage key off)
4. 0 volts to green fuel pump wire
5. 5.9v going to the blue computer wire..

if i take the cover off of the relay i can push the switch over with my finger and the fuel pump will run.. my guess is that the computer isn't doing what it's suppose to be doing with the voltage coming from the eec relay.. but i wanted someone who actually knows how this all works to verify this before i go replacing the computer..

thanks in advance for the help,
bill

mjr46

did you check for spark?? stator supplies pip and is cleaned up through the tfi module/ amplified , ecm sees this signal = interprets as engine is cranking and in turn supplies ground to fp relay and hence pump runs

white91stang

nahh i didn't check spark cuz i figured since the fuel pump wasn't running it was in the fuel pump circuit.. i didn't think these computers were smart enough to be able to shut off one system when another isn't working.. how would i go about checking spark..

i went through the whole fuel pump diagnosis step by step and it led me to the computer.. i'm still open to suggestions though, i was just saying what i have found..

mjr46

grab a used spark plug pull a wire and put used plug in it and grund out the electrode and crank car over and look for spark jumping the gap...........and yes ecm is smart enough to not turn pump on if PIP signal is missing, pip = profile ignition pick up

for your reading pleasure:
http://sbftech.com/index.php/topic,588.0.html

white91stang

aight thanks for that article.. i have spark.. and i probed the tfi to see what was going on.. i have 12v to pip, 12v to spout, 0v to start 12v to icm, 12v to coil and the ground is good ( all were tested koeo)..

i used this test from the article; "Attach 12-vdc test light clip to a 12vdc source, probe FP signal wire with the test light, while you turn the ign on for priming 2-4 sec pulse, test light should blink...it blinks = replace FP relay....doesn't blink = next step." the test light was bright before key was turned on, when i turned the key on the test light dimmed a little and thats it, didn't blink or anything..

the next step says "At this stage of the tests, the reason the FP relay is not activating, could be caused by a faulty EEC relay, faulty wiring, or fubar'ed ECM." i'm getting my 12v from the eec relay and i tested the ecu wire and it proved to be good.. given the results i think i'm just gonna have to own up and buy the ecu..