I have a harness from reddevildriver.com and everything has been going great the last year or so. I upgraded my battery cables to a 0 gauge for the relocation kit today and drove about 5 miles on the highway. A number of fuel pump fuses have blown upon my testing. I thought it might have been the relay so I unplugged the relay and the fuse still blows! My next guess is the fuel pump has fried. It primed and ran for a bit once I got the car back home, now it is back to blowing fuses even with the relay unplugged. Is there a schematic of this harness for me to start with for troubleshooting?
The harness is wired same as stock, with the exception of no ALDL diagnostic connector since the 3800 is OBD2.
The supply wire from C203 B might be Orange/Black or just Orange. The wire that runs back to C203 to the pump might be Tan/White or just Tan.
What fuel pump are you running?
Unplug the oil pressure sender, leave in the relay and see if the fuse still blows. If that stops the fuse from blowing your oil pressure sender is bad. Note - with the sender unplugged the oil pressure gauge will show pegged high oil pressure.
[This message has been edited by phonedawgz (edited 05-31-2014).]
That does sound right now that I think about it... The battery did die on me while getting an alignment. I thought they might have just left the car on or something.
Also for troubleshooting - If the fuse is blowing right away when you turn the key to on - Try unplugging C502 and see if the problem goes away. C502 is the plug that connects the body harness to the tank harness. If with C502 unplugged the problem goes away, and with C502 plugged in the problem is there, then the problem is in the tank wiring or the fuel pump itself.
Popped with the ops unplugged and it did not pop with the C502 unplugged. There is a Grand National acdelco pump in there now. I have a acdelco pump for a 89 corvette I've never got around to installing. Looks like that's my weekend now
I had an issue where the wire harness ran over a heat shield and it shorted blowing the fuel pump fuse. It happened intermittently and was a challenge to discover.
Boostme I had a mechanic look at mine early on and he noticed my harness near the firewall was very close to the exhaust manifold and found them brittle and starting to expose wires. He fixed that and moved the harness further away from the manifold but for me it wasn't the problem but it is something to look for, which it sounds like you plan to. lots of wires so no fun to sort through at that point. something is exposed and touching. good luck.
while we're kinda on the topic of fuel pump circuits causing problems, my car (3800SC) will drain the battery with the fuel pump fuse left in overnight. pull the fuse out and no battery drain. New fuel pump put in because the old one stopped working (didn't change the battry drain problem). oil pressure switch was replaced when a new gauge (autometer) was put in so there is a oil pressure switch installed with only one wire going to the gauge. so it seems as though that should rule out the typical oil pressure gauge malfunction causing the drain. So problem appears to be focused in the pump circuit. Other than loose connections on the C203 where else does one look?
It's considered impolite to start asking questions in someone else's thread about a different issue that you have. What happens is multiple conversations on multiple subjects and it causes confusion.
I'd say unplug the connector feeding the fuel pump and see if it blows a fuse. If it still pops, unplug another section until it stops shorting out. Start isolating sections of the harness so you can find where the short is.
You can probably check for the short using your multimeter instead of wasting fuses.
Try it with the fuel pump relay unplugged but with the OPS plugged in. It will take a little cranking before it fires but see if that changes things.
Also the Grand National pump has a 15 A fuse on it's power wire, not a 10 like the Fiero. The wiring of the harness should be able to handle the 15 A fuse but don't go above that. Carry a fire extinguisher with you for the testing.
[This message has been edited by phonedawgz (edited 06-01-2014).]
I upgraded my battery cables to a 0 gauge for the relocation kit today and drove about 5 miles on the highway. A number of fuel pump fuses have blown upon my testing.
Have you considered your action replacing the battery cable as a contributor to the fuse problem??
------------------ Mark ' 85 2m6 3.4PR In the Great Northwest!
The harness is wired same as stock, with the exception of no ALDL diagnostic connector since the 3800 is OBD2.
The supply wire from C203 B might be Orange/Black or just Orange. The wire that runs back to C203 to the pump might be Tan/White or just Tan.
What fuel pump are you running?
Unplug the oil pressure sender, leave in the relay and see if the fuse still blows. If that stops the fuse from blowing your oil pressure sender is bad. Note - with the sender unplugged the oil pressure gauge will show pegged high oil pressure.
I had the same problem with my 88 2.5 before my swap. The oil pressure sender shorted internally and kept blowing the fuel pump fuse. I put in a 20 amp fuse in place of the 10 amp... Voila! Follow the flames and smoke to the source of the short!
The harness to the pump had a small chunk of insulation missing on the power wire, it was grounding out. Taped it up and tested it and Walla no more fuse popping. This has been a PITA!
