1994 chevy k1500 5.7 TBI
plenty of spark but no fuel at all
I replaced the fuel pump and filter today and no change... matter of fact the original pump is still good.

the fuses and relays are good but I am only getting 8.9v to the pump and I checked and cleaned all the grounds so it has to be somewhere and I just don't know where to start.

It happened when I took a turn and it just died out and hasn't started since (well it did when I put fuel in the tbi but only for a little while).

 

I'd try to find a wiring diagram for your truck and checking out the fueling circuit. The factory service manual may also have a troubleshooting procedure that you can follow if you can get a hold of one.

 

Enclosed are the schematics required for your vehicle... You will mainly need 94 Chevy 1 & 3 PDF

You are stating that you are only getting 8.9v to the pump.. That would indicate a bad wire.. Pumps require at least 10v. Look at 94 CHEVY 1.pdf .. There are two 10amp fuses for the ECM 1 and ECM B and another 20amp guage/idle fuse..

Have you checked voltage at each injector Injector 1 red wire and Injector 2 white wire should have 12 Volts. The ECM 1 Fuse feeds your injectors with the 10A fuse with 12+ volt

Now for the Fuel Pump

1. The Tan/Wht wire ties ito the B3 circuit on the ECM and the Fuel Pump relay and Oil Pressure / Fuel Pump Sensor
2. The Pink only goes to the Guage.
3. The Black wire is for ground
4. The Gray wire goes to the Fuel Pump relay.. This should have a 12+ signal to feed the pump

Hopefully this helps

 

Yea there is a fuse in the block and one in the engine bay... would it be easier to just run a new wire for it? I read somewhere else that it could be the ignition module also but that doesn't make much sense.

 

There could be a few culprit wires.. The Grey one needs to be tested for voltage.. The Fuel Pump relay and the Fuel pump as you see it feeds both items.. I would start there and check for 12+ on each..

 

You can see from the diagrams that the Ignition module (EST) wires only feed into the ecm.. They don't have anything to do with fuel..

Found another schematic that don't have anything to do with the problem you are having, But since I have access to just about any car's wiring schematic, I thought you might like it.

 

no power to the relay plug but still 8v at the pump connector on purple

 

Do you have 12 volts at the org wire with the on the fuel pump relay with the key in the off and on position ?

 

yes on and off

 

Purple ??? On the fuel pump relay, You should have 4 wires. According to the diagram 94 chevy 3.pdf

Grey
Red
Orange
Black w/ white stripe..

Do you have power at the orange wire ? It should have power no matter what position the key is on...

are those the correct colors?

 

Sorry, the purple is fed by the ECM... My Bad

Can you make a jumper wire from the Grey wire directly to the battery + side and see if your fuel pump works?

 

ok jumped power to grey and I got power to my pump unfortunately the injectors are not firing... this thing is so much moodier than my camaro

 

The purple wire is the + side of the fuel solenoid to provide enough voltage to the solenoid to activate the switch using the orange wire from the Fuel pump prime connector (Red Wire) and changes it to the Fuel pump (Grey Wire) through the use of the Orange wire

 

Remember not to leave that jumper in there as it will burn your Fuel pump motor out.. This is just a check for your fuel pump for diagnosis

 

Now disconnect that jumper from the + POS side of the battery and the GRY wire.

Then with the fuel pump relay plugged into the harness... now take a jumper wire from the Black wire w/ white stripe on the back side of the harness wire and run it directly to the - NEG term on the battery and turn the key on see if you get pump power.

 

We will work on injectors next if I can keep my open long enough.

Have you checked the fuse block for the 10Amp fuse to see it is good ? You can see the fuse blockon 94 Chevy 2.pdf for reference.

 

Sent you a private message..

 

the pump is getting power and the inj fuse is good and getting power