'87 TBI fuse issue

[400/400]

Blew a fuse in my '87 with TBI 350 today. While slowing to an intersection the truck stalled. It would crank but not fire. Listened for the fuel pump (electric in the tank) and couldn't hear it. Started checking fuses and found the ECM B fuse was blown. Replaced it and she fired right up. About 10 miles down the road it blew again. So I towed it home.

So the question is, would a bad fuel pump cause that fuse to blow? Or suggestions on where to start looking. What all does the ECM B fuse power? The pump was replace 5-6 years ago. I think the fuel pump is run through a relay on the fire wall.

Any suggestions are appreciated. Thanks in advance.

Also below is a pic of the manual. The ECM B fuse is at the lower left above the mounting hole.

[Front Range]

Quick internet search brought up a few that might help. Sounds like a short in the wiring on the way to the pump, or the pump.

http://www.astrosafari.com/viewtopic.php?f=4&t=4746

http://www.justanswer.com/chevy/49ld...own-truck.html

http://www.s10forum.com/forum/f135/e...lowing-411116/

[chengny]

Here is a wiring diagram for the fuel pump/FPR circuit:



And a couple of pages dealing with a Code 54 (low voltage condition in the FPR circuit). You're probably not throwing a code but the diagnostic may be useful:



As to the location of the oil pressure switch used in the fuel pump circuit - it may be either down by the oil filter or in the usual spot (behind the distributor). IDK these engines very well. If it exists, the oil pressure switch above the filter looks like this. Due to it's location, it may be a good place to start checking for wiring issues:

[JW76]

Check the little diamond shaped plastic block on the firewall that the power wires run to. The tie between the two posts cracked on mine and was contacting the firewall and blowing the ECM B fuse. I chased the problem all over. I finally gave up and starting pull the harness out of the truck and noticed the issue.

[bealaddison]

My '87 Suburban did the same thing. I replaced the fuel pump and that was the end of it. More than likely you have a bad fuel pump.

[87 STEPPER]

1st. thing I'd do is undo the connector at the frame that go's to the pump and sending unit and fab up a pig tail with a inline fuse and run 12v straight to the pump it's either gonna run or blow.

The power distribution block on the fire wall is easy enough to check first too!

Good luck.

[slug]

Originally Posted by 87 STEPPER

1st. thing I'd do is undo the connector at the frame that go's to the pump and sending unit and fab up a pig tail with a inline fuse and run 12v straight to the pump it's either gonna run or blow.

The power distribution block on the fire wall is easy enough to check first too!

Good luck.

Good idea. I did the same on my 87 when I got it to figure out which fuel pump was good and which was bad.

[400/400]

Thanks for the suggestions guys.

It took a few weeks before I had a chance to work on it. I think it's fixed. I started by turning the key to the run position without starting the truck to see if the fuse would blow without the pump running and it didn't.

So I figured replacing the pump was a good place to start as I think it was still the original. Haven't put too many miles on since replacing the pump but it hasn't blown the fuse yet.