stratman977 Posted November 26, 2014 Share Posted November 26, 2014 I was just getting off the interstate and downshifted twice, my headlights go bright for a second then everything went out for a second then came on. At this point my engine was dead so I pulled off. It wouldn't start. I connected the green connectors for the ecu and the fuel pump wasn't coming on like it should in test mode. My buddy pulled me up the road and in the shop we found that the fuel pump ign fuse was burnt. I put a new one in and it started right up. I drove it 15 miles home and it was fine. I know fuses don't blow for no reason but is it possible that the fuse was just old and had one too many voltage cycles. The only electrical gremlins on the car is my check engine light doesn't always come on when the engine is off but ignition on and the idle air control valve has a loose connection cause some times it opens and closes while running or wont come on for a cold start. That one is hard to find the fault cause its intermittent. I did run wires to the speakers to fix the common ground over the weekend but I don't think that's related. Any ideas on things to check? Im going the inspect the obvious wiring for a defect but what else to look at since its currently working. Its a 1988 gl wagon 4wd ea82 spfi. Link to comment Share on other sites More sharing options...
DaveT Posted November 26, 2014 Share Posted November 26, 2014 Fuses can just fracture from age , temperature cycles, vibration. The ones I've seen fail from these causes usually don't look bad. A blow from severe overload usually has dark / burnt marks . I should make sure I have spares in my cars.... Link to comment Share on other sites More sharing options...
Dee2 Posted November 26, 2014 Share Posted November 26, 2014 Sounds like you're on the right track. Fuses will blow when there is stray wire that grounds out somewhere. Can be hard to find. Link to comment Share on other sites More sharing options...
jono Posted November 26, 2014 Share Posted November 26, 2014 the main fuse just off from the battery pos terminal - known as fusible links - check them for integrity. It may just be the fuel pump is on its way out and may do it again. A new pump, may or may not fix the problem. 1 Link to comment Share on other sites More sharing options...
MilesFox Posted November 28, 2014 Share Posted November 28, 2014 I would guess the alternatior is old and the voltage regulator may be overcharging. It can voltage spike and for the same amount of impedance in the circuit with increased voltage causes increased amp draw which can overrun a fuse or burn stuff out. Charge output should be within 14.5 and 13.5 and the battery at rest should be at 12.4-12.6v (with surface charge) Link to comment Share on other sites More sharing options...
stratman977 Posted December 14, 2014 Author Share Posted December 14, 2014 (edited) So 3 weeks later and I'm still fixing this. I put in a new fuel pump and a new coil and I took it for a test run and sprung a leak in the fuel line. It had some rust where it goes through the support brackets. I make a new fuel line and again take it for a test run and low and behold I sprung a leak in a brake line. So I repaired that line and go for another test run. Of course, I blew a fuse. I made it home but I made unplanned 3 pit stops in 5 miles to change the fuse. When the fuse blows I can hear a click under the dash. The only other thing other than wiring in that circuit is the fuel pump relay. Thinking about it now the fuel pump isn't actually powered by that circuit, its through a relay. I found two relays under the hood by the vacuum check valve but none of those seemed to be it and there were 4 silver ones under the dash but none of those were it either. I was looking for the black and white wire coming from the fuse box and also testing for continuity at the connectors. Where in the heck is the fuel pump relay? If this isn't it I'm out of ideas. Edited December 14, 2014 by stratman977 Link to comment Share on other sites More sharing options...
Hsoj Posted December 14, 2014 Share Posted December 14, 2014 Its the brown box above the hood pull in and ea81, I think its in the same spot for an ea82...(Gosh, its been a while for me on an ea82!) Link to comment Share on other sites More sharing options...
stratman977 Posted December 14, 2014 Author Share Posted December 14, 2014 I found it, it's above the computer behind this metal brace for the steering column. I tore it apart and it doesn't look bad to me, nothing obviously burnt or broken. Not sure what to do next. Link to comment Share on other sites More sharing options...
stratman977 Posted December 15, 2014 Author Share Posted December 15, 2014 The wire that comes off of the magnet side of the relay runs into the ecu. Is all the ecu actually doing is grounding out the circuit to turn the fuel pump and coil on or is it doing something else in addition with that signal? I want to isolate the coil and the fuel pump from everything else and put them each on their own 15a fuse to see which one of the two is causing the problem. Just wondering if it will run with the computer bypassed? Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted December 15, 2014 Share Posted December 15, 2014 As has been mentioned, have you checked your alternator output? A random voltage spike can fry a lot of different things. Also, have you checked the backside of the fuse box for corrosion/broken/frayed wires? Twitch Link to comment Share on other sites More sharing options...
stratman977 Posted December 15, 2014 Author Share Posted December 15, 2014 The alternator checks out fine. I suspected maybe it had some a/c ripple but a/c voltage was hardly measurable. I also haven't any odd behavior leading up to the handful of blown fuses since then. I also had the fuse panel out yesterday when I was looking for the relays and it looked ok to me. There wasn't any noticable corrosion. I did take the cover off the computer to see if there was anything obviously toasted in there. The circuit board looks great but I noticed the cover which would be on the bottom in the installed position had a spot of white powder on it. Kinda looked like an alkaline battery leaked in there. I was expecting to find a burst capacitor but theres nothing that looks like it would have went bad. This powder looks as if its been there for a long time though. I'm going to try to get another computer and see if it makes any difference but im not cinvinced that it will do anything. Link to comment Share on other sites More sharing options...
stratman977 Posted December 17, 2014 Author Share Posted December 17, 2014 I ran it today in the driveway for a good 30 minutes and nothing happened. I also drove it locally about 10 miles and no blown fuse. I felt the coil and fuel pump and neither were even warm so its not heat related. The only thing different was the relay I changed. I need to stock up on fuses and go for a longer drive before I can trust it again. Link to comment Share on other sites More sharing options...
Gloyale Posted December 19, 2014 Share Posted December 19, 2014 This all started after you were in the dash running new wires for the stereo. I will bet you've got a wire under there that is touching ground and shorting out to blow the circuit. 1 Link to comment Share on other sites More sharing options...
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