No power to fuel pump
Thread Starter
7th Gear
Joined: Jun 2004
Posts: 7
Likes: 0
From: Rancho Cordova California
No power to fuel pump
I have an 86 coupe with 145,000 miles that won't start. I had the same symptoms almost two years ago and paid too much to get it fixed.
That time, the shop told me that my factory security system "freaked out" and blew all my fusible links, and they all had to be changed. Supposedly some were inside the dash and what not; that was his justification for the labor involved.
This time, it started when my battery died from sitting for too long. So, I charged it overnight, and when I tried to start it I got crank but no start. I checked underhood and found a blown 15 amp fuse, in place of a fusible link that provides power to the fuel pump relay. That explains my lack of fuel pressure. But whenever I replace the fuse and turn the key, it pops again. If I unplug the relay and turn the key, nothing happens. But if I plug in the relay, the fuse blows. I tried just jumping the hot lead to the fuel pump, and it blows as well, which makes me think the relay itself is OK. As far as I can tell, the problem is after the relay but before the fuel pump, as I unplugged that and had the same results. It must be a short somewhere, but I don't know where to check next.
Any help would be appreciated.
That time, the shop told me that my factory security system "freaked out" and blew all my fusible links, and they all had to be changed. Supposedly some were inside the dash and what not; that was his justification for the labor involved.
This time, it started when my battery died from sitting for too long. So, I charged it overnight, and when I tried to start it I got crank but no start. I checked underhood and found a blown 15 amp fuse, in place of a fusible link that provides power to the fuel pump relay. That explains my lack of fuel pressure. But whenever I replace the fuse and turn the key, it pops again. If I unplug the relay and turn the key, nothing happens. But if I plug in the relay, the fuse blows. I tried just jumping the hot lead to the fuel pump, and it blows as well, which makes me think the relay itself is OK. As far as I can tell, the problem is after the relay but before the fuel pump, as I unplugged that and had the same results. It must be a short somewhere, but I don't know where to check next.
Any help would be appreciated.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by SilverBeast
If this just started and you have not messed around with wiring, then there's probably a short in the fuel pump itself.
Originally Posted by Nak
As far as I can tell, the problem is after the relay but before the fuel pump, as I unplugged that and had the same results.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Take a look at the wires as they go into the FP relay. Make sure the insulation hasn't shrunk, exposing the wire.
If that doesn't do it,... you will need a Helms manual to see where the wire actually gets routed,... then trace it out.
As for VATS going nuts and blowing fusable links,... That's BS, in my book. I suspect somone has mess w/ your electrical before.
If that doesn't do it,... you will need a Helms manual to see where the wire actually gets routed,... then trace it out.
As for VATS going nuts and blowing fusable links,... That's BS, in my book. I suspect somone has mess w/ your electrical before.
Thread Starter
7th Gear
Joined: Jun 2004
Posts: 7
Likes: 0
From: Rancho Cordova California
Solved
Well I finally figured it out just before dark last night. Apparently, that same power wire feeds two other relays in the engine compartment behind the battery. The MAF Power relay was stuck closed, creating the "short" that was blowing the fuse. Once I replaced that, the car started right up. THanks for the info and support, everybody. 
