Can't here the fuel pump running. Checked fuel injection relay in the fuse box, check relay for fuel pump, ohm fuel pump. I got it narrowed down to computer. Could it be anything else?

 

Welcome to YotaTech.

First, it's not the computer (ECU). The ECU has nothing to do with the fuel pump.

Try describing your problem a little more systematically. You can't hear the fuel pump .... when? You're not supposed to hear it with just key-on (it comes on with key to STArt, then held on when air is pulled through the VAF). How did you check the EFI relay? Where did you find, and how did you check, the "relay for the fuel pump"?

Using your multimeter (no multimeter? No excuse for that! https://www.harborfreight.com/7-func...ter-63604.html) with key-on, check for battery voltage on B+ in the diagnostic connector. Jumper B+ to FP; with key-on, you should hear the pump running. If it starts now, you've narrowed the problem down to the VAF COR circuit.

Next time you post, be sure to tell us what vehicle you're talking about. (Make, Year, Model, Engine, Transmission) If you like YotaTech, you'll want to just put that info into your signature.

 

just a little history.. 4 years ago I hard a problem took 5 to 6 cranks to start, then later that week 10 to 15. When it starts runs all day until it cools down end of work day the same thing later. 3 mechanics later tried the computer it worked.. Ever since then with refurbished computers turn the key on the fuel pump start.. It was not like that before, it was just as you explained.. So the last four years I could hear the pump cycling. So when I turn the key on no noise.. I replace the EFI relay and the fuel pump relay I clean the contacts and I can see/hear it clicking and making contact.. I ohm the fuel pump and motor showing good... FYI the pump I replace 4 years ago when I was having problem.. But it did not fixed my problem until my mechanic replace the ECU.. Soon rely so long

 

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So if your pump runs (ran) with key-on, somebody has messed with your fuel system wiring. You absolutely need to get that fixed (it's a safety issue). The tests I described will help

Assuming you have a Toyota 4runner or truck (you still haven't told us), you don't have a "fuel pump relay" (that's why I asked where you found whatever relay you messed with). The fuel pump circuit includes the Circuit Opening Relay. Is that the one you "cleaned" and "saw clicking" ? Clicking is better than nothing, but it is certainly NOT "checking" the relay. Did you get battery voltage on the pump contacts? Do you even know which contacts go to the pump?

"Ohming" the fuel pump doesn't really tell you anything (the DC resistance of a good pump is basically the same as a short), so you could have a frozen pump, or bad wiring. Once your ohmmeter told you there was a connection from where ever you tested to the pump, you could have put 12v (through a fuse) on the pump and tested it.

Last, to be sure I didn't miss anything obvious, I assume you care because your truck won't start, even though it will crank. And you don't have a Check Engine Light.

 

Like scope says ^^^
Assuming you have a low-end 1986 22RE like mine, not an Escalade....

https://www.yotatech.com/forums/f116.../#post52387681

 

So far thanks for your input. I have a 91 4x4 Totota pickup, 22RE, 5 speed, 4cyl. the relay I tested is in the fuse box, the second is right by the ECU by the passanger feet right side.

 

Then that is the COR.

I can't help you any further until you do some voltage-to-ground measurements.

Good luck!

 

I put 12 volts directly to the pump and the pumps motor works. I check voltage going to the pump and I get 12 volts.

 

You realize that makes no sense. The stock wires have 12v, but the pump won't run unless YOU put 12v on the same wires?

IF you have a very high resistance connection, you can get 12v Open-circuit on a pair of wires, but when you connect them to a low-resistance load (like a fuel pump), the voltage drop in the connection causes the voltage AT the pump to fall so low the pump won't turn. That would be if you check the wires headed to the pump with the pump disconnected.

Maybe if you describe your test more carefully. Where are you doing the measurements? Both AT the pump? With the pump connected or not?

 

I put 12 volts to the pump wire and I can hear the pump, why doesn't that makes any sense?

 

Ok this may help you understand, I disconnect the connector coming from front of truck going to fuel pump in the tank. I supply 12 volts directly to the pump, the pump runs. Then I checked the wire coming from the front of the trunk when I start it I get 12 volts.

 

Does the pump run "when [you] start it"? If the pumps runs with 12v direct, and the pump wire has 12v, how could the pump not run?

 

Have you checked the "Circuit Opening Relay?" It is just above the "computer." I have had to replace mine twice since 1992. There is a work around.besides testing it. Just run a wire from one of the prongs in the relay harness directly to the positive battery terminal. If you run the wire from the battery first, then touch it to one of the five female plugs in the relay harness, you should hear fuel entering the "rail." There may be a jumper needed in the small diagnostic terminal under the hood as well, but I can't remember. Hope this helps.
Sea

 

 

Op when your reading 12 vdc at the pump connector .

You have the B+ Fp connection jumped with the ignition on??

 

I tried checking volts on those pin with truck ignition on and nothing.ust a little history.. I'll give you a little history , 4 years ago I hard a problem took 5 to 6 cranks to start, then later that week 10 to 15. When it starts runs all day until it cools down end of work day the same thing later. 3 mechanics later they tried the computer it worked.. Ever since then with refurbished computers turn the key on the fuel pump start.. It was not like that before,. So the last four years I could hear the fuel going to the rail. So now after the truck stalled last Sat when I turn the key on no noise.. I replace the EFI relay and the clean fuel pump relay, I clean the contacts and I can see/hear it clicking and making contact.. I ohm the fuel pump and motor showing good... FYI the pump I replace 4 years ago when I was having problem.. But it did not fixed my problem until my mechanic replace the ECU.. I disconnected the fuel pump wire going to the front of the truck, supplied the pump with 12 volts and I can here the pump in the tank. I got 12volts whenever I crank the truck from the other end..

 

It would not be the first time the fuel level is below the pump

 

Thank you all for the advice and input. After disconnecting the 12 volt pump connector coming from the front of the truck, I supplied 12 volts directly to the pump itself. At times the pump motor sounds strong and the trunk started, then after a few minutes the motor slowed down and the trunk doesn't start. I changed pump motor, screen pickup and fuel filter and problem solved. Keep in mind my trunk has over 450,000 miles; however the pump, the screen and the fuel filter was changed 2015.
Thanks again you guys rock....

 

Glad u got it fixed. But, to help others, care to share what pump u got this time and the pump that only lasted 3 years so we can avoid it?

 

The first pump was from NAPA auto parts not sure of the brand. The new pump was from Advance Auto Parts, I'll check into on the brand later.
Thanks again.