Fuel pump not working

Thanks for helping!

This truck has the TBI system.

I have never gotten a peep out of the pump even after replacing all the above mentioned parts. As mentioned I can get the pump to come on if I hot wire (jump) the fuel fuse on the firewall next to the fuel pump relay. I can only get the pump to fire in this manner by using a separate power source I.E. A jumper wire from the positive battery terminal. This is the fuse wired to the relay and ECM with a gray wire. With this I assume the wiring to the pump is sound.

But even with the pump running like that, the injectors are not cycling or spraying any fuel when I have the ignition on.

I am not up on how to properly test whether power is being supplied to the ECM and whether power is coming from the ECM to the relay. I have used a meter on some of the wires and some show hot though I do not remember which.

I am in training at a distance from the house right now so I will not be able to work on the truck until Friday, but any help in sending me in the right direction is really appreciated.

Thanks.

Okay, I have had a chance to check some things. I rechecked the pump and it fires good and pressure is +55 at the throttle body. It still will not come on with the key/ignition and the wiring checks out when I hot wire from the fuse plug near the relay. I checked power to the relay and the orange input power wire from the ECM is hot with the key on but no other coming out from the relay. Checked for good ground there/okay.
So still no power to pump! Power in to relay but none out and it is a new relay!
Checked power to injectors and the hot wires are hot when key is on and when the other side is grounded they will fire. I hot wired the pump and grounded the injectors one at a time and they sprayed fuel big time and the engine would start. But without manual grounding the injectors will not fire or pulse. Well I am closer but no closer if you know what I mean. I am still at a loss as to what the problem is. Why will the pump not come on and why will the injectors not fire? Please help!

Soonerbills, my truck is fixed. It was the fuel pump but once I changed it, I had to ground a contact on the test connector that specifically tells the ECM to close the fuel relay. Once the pump ran, I removed the ground and started the truck. Without doing that, the ECM did not power the relay. Go look at my post
1993 Chevrolet Truck no fuel to TBI.
There is a real good information that Merlin2021 provided and the answer may be that simple. The ECM gets it reference pulses from the ignition module to operate the fuel relay to keep it working and will shut down the fuel pump after two seconds if you stop trying to start the vehicle or there are no reference pulses. I think this will help you. Send me a post when you have success!

Soonerbills,
I forgot to mention this. In your post you mentioned the fuel relay having power on the orange wire but nothing else. Your trucks diagram probably is the same as mine. You mentioned jumping power to the fuel pump wire. If it is a gray wire, then you probably have a green/white wire that the ECM energizes the relay coil with. I use a sewing pin to pierce the wire to read the voltage when you can not get to a contact. You already changed the relay and I bet it is the ECM that is not providing voltage to power the relay because the ECM is shut down and not broke.

Do not know the electrical diagram for your truck but on mine, the coil winding is grounded on one end the the ECM applies power to energize the relay coil. When you turn the key on, twelve VDC is applies to one of the relay contacts and only when the ECM applies voltage to the coil does the contacts close and feed voltage to the fuel pump.

The truck is now running!

Turned out that a cut wire (green/white) to the relay was the culprit. Previous owner chopped off the o2 wires, ran a straight exhaust and cut through the harness in the process, nailing the relay wire. This fried the ECM and after replacing the harness I was able to get the truck started.

Now I have find out why it is rough running and stalling at idle.

Thanks guys!

Soonerbills, success feels great now that you fixed your truck. Bummer that one spends so much effort but I can definitely tell you this site saved me some time and I have learned from it. I appreciate the reply that you have it working. I hoped the information I sent helped.

Need help please badly. 1992 Chevrolet c1500 4.3 truck. Put in new fuel pump. TBI, fuel pump coming on when key on. Turns over with it. Injector working but right one does not work when trying to start engine.

Question I have to be sure. Should engine not start if only one injector is working? Know it would only run half the six cylinder engine but should it not start?
Then I could be more sure I have just a bad injector the problem?
Is it certain if fuel relay is cutting on fuel pump when turning key on its okay?
If injector on right. Checks out okay when I do the transistor battery test on the not working fuel injector on right. Side and it is good where do I go then?
I have power to left side injector.

Okay to make better sense. If truck should crank and run on one injector working I am lost.
Also, if right injector is good I am really lost.
Hope people understand where iam at. Please give me all your thoughts what I may be missing. Thanks to all.

Again need help I am sixty two years old, on disability with no money pay get fixed. Please read above. It is old truck but all I have. Need help so badly.
Someone please tell me what to check and test next in detail. I need my truck get to doctors and food.

You are nice people here knowing it is the fourth all with there families as they should be. Mine are grown. Not out to help me anymore.

Way it goes with many older people. All enjoy your holiday and family. It is so important to have a close net family.

I do not have that. Sorry to bother you with my problems. Sit at home and wait for help. One day I did not needed help as now. If broke I worked on it until I found problem.
Now I need help to find the problem. Again you please write in.