KEEP WISHING

I have a little problem that maybe needs more expertise than I currently hold. 1990 4.0 renix
I have no fuel pump prime or turn on. I have worked off and on for a year now trying to figure out why. This is what I have done so far...
New grounds, all electrical connections have been cleaned and relays checked. I have .17v at the pump but cranking voltage at the spice where the ballast used to be. Found .17v at all plugs in the cab by following the pink w/ black strip wire. Took the computer out and checked connections, all looked good.
Checked the B+ and fuel pump relay and all have power. Jumped the fuel pump relay and the darn pump came on. Put everything back together and hit the key and she came alive for 5 sec. Still no prime or pump.
I got curious and splice the terminal 86 on the a/c relay to 86 on the B+ relay and got both pump and prime. Actually drove the beast.
Now I'm not one to leave something rigged so I want to get this fixed. Is this a computer issue? Here in Florida its hard to survive without a/c.
Any thoughts?

KEEP WISHING

There has got to be a renix expert somewhere out there.

toasterknight

That would be cruiser54 he will always save the renix jeep owners.

KEEP WISHING

Yea I've read some of his posts. I have searched and searched for this problem on the forum but they all are a little different situations. Was supposed to show the beast next month at a show with a fresh coat of paint but this is not looking good.

freegdr

Whats the voltage at starter relay ? What plugs.....Found .17v at all plugs in the cab by following the pink w/ black strip wire

KEEP WISHING

I have starting voltage there at the starter switch relay. I found a connection at the drivers kick panel .17v cranking, followed the pink with black wire to a bundle under the dash that splits and goes out the firewall behind the fuse box and the other heads toward the computer. Have .17v cranking at the wire going out through the floor under the back seat. But when I switched 86 on the Ac relay to 86 on the B+ relay I get prime and cranking voltage. That means the wires are good to the pump right? Seems like the pink 86 circuit is not doing its job. Whatever that may be. Diagram shows it going to ecu.

KEEP WISHING

I looked and there is a fuel pump wire going to the coil. ??? Shows 3 wires, fuel pump, ground and tach. What does this do?

cruiser54

I would check to see how much voltage is at that wire right at the ECU.

KEEP WISHING

Thanks cruiser. I will give it a shot.

KEEP WISHING

Cruiser maybe you can help clarify. Checked the wires at the ECU, went back to the B+ relay then back to the ECU. Done this about 6 times to check myself. I am getting power to 30 on the relay in the off position. Which is good. With the key on i get 13.2v at 30, 10.8v at 85,86,87. ???? ECU 10.8v at both wires A-9 and B-10. Shouldn't A-9 be a ground for the relay? The relay clicks on and off but holds voltage to all terminals.

cruiser54

85 is relay ground at the ECU.

KEEP WISHING

Replaced the ECU tonight and the beast is up and running. After finding voltage on the B+ group at the ECU figured it had to be the problem. Good news is i have repaired or replaced all faults in the wiring system and learned a ton about renix. Thanks for helping.