88 K5 Will not run - only 8.48 v at fuel pump!

[THEMCGUIRE]

Driving along, truck just died. No fuel at injectors.

I replaced the: fuel pump, fuel sending unit, filter, fuel pump relay, MAS sensor. I shot compressed air through the fuel line from the pump to the filter.

Still will not start, no fuel. Starts with starting fluid.

I am getting 8.48 volts at the white striped tan wire going to the fuel
pump.

Is this enough voltage ? If not, Can I send 12 volts directly from he battery?

If it requires 12 volts any ideas why voltage is low with new relay and pump?

[oakknight]

on my 89 I had a situation like that where the truck seemed fine then cut out and was dead . would turn over but not start .. while working on the problem we found out that the Ignition modeule was not sending the right signal to the ECM to fire the injectors.http://www.streetperformance.com/par...637-35370.html

[THEMCGUIRE]

Thanks, I will check the Ignition control module. (I did some searching for the name.

[sanddragon2004]

try running a new power wire. even just a jumper.

[THEMCGUIRE]

I would try that but I do not know if 8.5v is correct or not. Can I run a line directly frorm the battery at 12.8v ?

[Thunder]

There is a fuel pump relay located on the firewall behind the right side of air cleaner.
it has a red wire hanging out of it not connected to anything. Run 12v + from the batt to the red wire. That bypasses the relay, Your fuel pump should run.
Possible that the contacts in the relay are worn and not passing full voltage.

Behind the distributor there is a oil pressure sensor. It is aslo wired in the starter circut. It is a failsafe that will keep the engine running as long as there is oil pressure, if the fuel pump relay fails. Possible that voltage drop may be there.

Also could be a bad dist module or pick up coil as said above.
But the fuel pump should still run if 12v is connected to the relay bypass wire no mater what.

[THEMCGUIRE]

Thanks for the advise.

I tried the relay bypass and got 12 volts at the fuel pump. Still no start.

I replaced the Ignition control module also no start

A MAJOR point I forgot to mention is that The engine starts and runs as long as I spray starting fluid.

Also, I had put it out of my mind but:

This is my second new fuel pump. I had the key on when I connected the battery after putting in the first fuel pump. But I did not have any gas in the tank. I heard a loud whine and then nothing. I had fried the pump because it did not have any fuel to lubricate it. This means that the electric to the pump was working.

So I have now ruled out the following:

1. Ignition because it starts and runs with starter fluid.
2. Electrical because I was able to fry the first fuel pump and now have 12v at pump

I do not see or smell gas at the throttle body. Tomorrow, I am going to disconnect the fuel filter and see if it is pumping any gas.

Also, is it a good idea / safe to blow air from the fuel filter to the "carb"?? Will this damage the injectors?

This test would eliminate any issue of cloging - is there a proper way to do this test ?

Any other ideas ?

[sanddragon2004]

hows fuel pressure?

[sanddragon2004]

clogged filter or perhaps bad fuel pressure regulator?

[Thunder]

I tried the relay bypass and got 12 volts at the fuel pump. Still no start.

If the pump wont run when you power the bypass and you have 12V back at the pump it is either bad or maybe the wires got disconnected in the tank.

If you replace the pump it is best to use only AC delco replacement or genuine Walbro.
many of the rest of the fuel pumps are imported fron china junk.