Now my 93 is not turning over with new fuel pump

[daisyrocky]

This morning driving to pickup parts for my 95 Ex and on way back my 93 just cuts off, battery lights and all. Coast her to the side of road, will crank but won't turn over, checked the inertia switch did not pop up. Called flatbed service and towed back to house. Went and brought new fuel pump assembly filled and new gas filter and fill up with gas jug still won't turn over. No regular buzz/humming noise when turning key over. Any idea?

 

[daisyrocky]

It's not the fuel pump, attached 12 volts jumper to it and it powers up. Check and swap fuel pump relay still won't power up fuel pump. Check all fuses in power distribution all fine. What can it be?

 

[nitro71]

Could be your battery terminals. Mine were corroded with a dark black corrosion. Kept it from starting. Having a hard time following your post but can't hurt to check your terminals.

 

[MrShorty]

Does the pump run if you ground the fuel pump test lead (short side of trapezoid in self-test connector if memory serves)?

PCM is responsible for closing the relay. Is the PCM sending a signal to the fuel pump relay to close? If not, is the PCM getting power (might start by checking the EEC relay to see if it closing with the key on).

 

[daisyrocky]

Thank you all. I'll try that in the morning since it's pouring rain out there now. Really worry that it will be the expensive PCM module. This is getting kind of ridiculous. My 95 have the OD Off light flashing issues with the tranny acting up and relying on this good old 93 to get me to work and now this. Unbelievable!

 

[daisyrocky]

Been reading past posts all night and found the EEC big fuse blown, tried three new ones and they keep blowing as soon as I turn the key. Any idea where to start looking or tracing? Thanks!

 

[daisyrocky]

Been tracing all wire harnesses and found the problem. Truck starts right up. Thank you all!

 

[MrShorty]

Glad you got it fixed. Would you care to share where the short was? Shorts that blow the EEC fuse are sometimes hard to find because there are so many possibilities. Other people may find it useful to know where your short was and/or how you managed to locate it.

 

[daisyrocky]

First, thank you all and it was a lucky shot. I took all fuses, relays, diodes out and tested them all like you recommended. All good except EEC 30A fuse when I turn the key you hear the fuse pop. I went to the pump and traced the wires still no power to the fuel pump harness, tested the ignition switch it was OK. Then I went back under the truck and followed the fuel line to the pressure regulator and still no fuel. Check the diagram you guys supplied and followed every wire harnesses the PCM output to and found one skinny harness right between the transmission bell housing and under the driver side exhaust manifold which the harness was laying and touching against a exhaust pipe bolt. It melted two wire which I thought was black but was red due to the burnt and the other was yellow. That was it, the truck started like nothing ever happen. This harness must be view from under the driver side looking up to the engine compartment. Hope this helps other out.

 

[fixxxer]

Thank you for updating the thread with what you found. I seem to remember a post from several months back where almost the exact thing was happening and I believe the problem was almost identical with a wire or wires near the exhaust had melted insulation and had shorted out and caused a fuse to keep blowing.

 

[daisyrocky]

No problem, if I remember correctly the harness has 5 or 6 wires in it. It's not a thick one but the size of the wires were at least 16 gauges since I was wrapping them up. Hard to believe it completely disable the truck like that.