Topic: no power to fuel pump???

[crawlnbeaver]

hey guys im sorta but not really a newbie, i just havent posted to the site much because i can usually find all the answers i need when useing the search so i dont know where else to post this. but anyways i have a 91 toyota 4x4 that im currently working on. i bought it from a guy for 2000 who had it 3 linked w/ fox air shocks and 36" tsl's that are 80% tread with a 22re and the w56 tranny running toyota axles, i thought it was pretty cool but the catch was it didnt want to start. so i went through it and figured out that the cold start injector wire wasnt conected and the o2 senser wire was cut. i fixed the wires but didnt tape the o2 senser wires. well i have been redoing the 3 link and had stuffed the o2 wires up out of me way so that i could gring some left over brackets off the frame, then i went to start it and wouldnt start, it kept blowing the efi 15A fuse under the hood,  so looked it up on marlin and found out it was thoses stupid wires shorting to the crossmember. taped them up but now im having problems with the fuel pump...

im getting about 5.56 (volts i want to say) when putting the volt meter to the male end of the fuel pump wires right at the tank on the blue wire. thats when i turn the key to the start position and when in the on position it floats in the .1 range. i havent been able to find this problem on marlin and was wondering if i would have messed something up like a circut opening relay or some other relay switch. idk whats going on but im not getting any fuel. i did check the big efi relay on the fuse block under the hood for ohms and continuity between the number 1 and 3 terminals....

please help,
kevin

[crawlnbeaver [OP]]

the main efi relay check out fine.

kevin

[jimbo74]

the fuel pump has it's own relay, check that...... also, it has it's own fuse too

the fuel pump is gettign some power and still wont turn on at all? considering it is a dc motor, it should turn on even a little bit if powered..... also, i find it wierd that when power is applied, it loses it's connection, or then has a short in the circuit

[yotaneck13]

the relay for the pump should be behind the glove box with the fuse unser the hood.  If its getting some power tho i would think these are good.  send me a pm if you come to the conclusion it is the fuelpump thats bad i have a like new toyota pump and sending unit i bought both new from toyota and parked the truck for a 3.4 swap a month later

[jimbo74]

i would try to jumper the fuel pump with 12v, and see if it starts pumping..... just make sure to use a switch, well away from the tank or any open fuel or vent lines......

[crawlnbeaver [OP]]

ok so i made a jumper, hooked it to the pump first then the battery, and it definatly turned on, i had the fuel line disconected running into a fuelcan and it gushed out... when the o2 wires shorted do you think it could have fried the fuel pump relay, im going to check it next and clue on what ends im supposed to test, like i did on the efi relay? there was a relay box that was behind the passenger side kick panel that had the same blue wire that was running from the pump whould that be it? and i didnt see the fuse for the fuelpump under the hood, what abreviation would it be/ called?

thanks again,
kevin

[superyota]

the fuel pump shouldn't come on when the ignition is turned on.  it is pulsed power that comes on when the engine starts cranking and is sent by the ecm.  if you have a good scan tool, you can splice into the blue wire at the fuel pump and check it when cranking to see if its getting power.  you have to do a freeze frame to actually see it.  i would try cranking it with the fuel line loose and see if you get fuel, or try putting a test light in the diagnostic port and check for a light when cranking.

[yotarunner85]

Check fuses EFI 15A & IGN 7.5A.
Check for 12v at Diagnostic check connector B+ terminal with the key in the run position.
You can bypass the fuel pump relay by jumping B+ terminal to the Fp terminal at the diag. connector with the key in the run position to see if the pump runs.
If it runs then you have a problem with the relay circuit. Check for 12v at the STA & B+ terminal at the fuel pump relay. Also check relay ground circuit.
If it doesn't run check for 12v and ground at the pump connector. IF you have 12v but no ground fix the ground circuit.
If no 12v to the pump check wirring from fuel pump relay to fuel pump.
Hope this helps.

[crawlnbeaver [OP]]

man this is a tuff bugger thank you for all the input. my brother and i have tried everything you guys have said plus other research and nothing,  i guess its time to start digging into the wiring. im always open to any other suggestions you fellas might have, and thanks again

-kevin

[yotarunner85]

Did you check the things I listed? What are the results?

[crawlnbeaver [OP]]

Did you check the things I listed? What are the results?

my brother was doing everything you said so i'll have to have him tell you what happend, just wiating for him to come back down, not ignoring you... and thanks for the help actually i'll prolly double check his work here when the sun comes out

[yotarunner85]

Just trying to help. Don't like to see broken down yotas.

[crawlnbeaver [OP]]

Did you check the things I listed? What are the results?

i checked both efi and ign fuses and they are good.

at the diag. connector with the key "on" i checked B+ for power, the result is .175 VDC.

with B+ and Fp jumped at the diag. connector the fuel pump didnt turn on. i also checked how much power i was getting to the pump connector and the result was .156 VDC.

with my meter now on continuity check i placed one of the meter prongs in the negative side of the pump connector and placed the other meter prong against the frame. the result was a solid tone with resistance of .010. so i have a good ground, right?

Check for 12v at the STA & B+ terminal at the fuel pump relay. Also check relay ground circuit.

how do i check the STA and B+ terminal, not really good at looking at a diagram and dont know where to find these, just confused.

i also checked the positive wire with my meter on the continuity check from the pump connector to the connector under the seat inside the cab and the result was .000 resistance. then i checked from the connector under the seat to the pump relay plug connector and it also showed .000 resistance.

thanks,
kevin beavers

[yotarunner85]

You should have 12volts at the B+ in the diag connector with the key on. Did you check to see if you have 12v at the ign & efi fuses?(both sides of the fuse) If you have 12v at both fuses then you need to check for 12v at the efi main relay. You should have 12v at pins 1 & 2. Pin 3 should be ground. Pin 4 goes to the relay for the fuel pump. Here is another diagram.

[crawlnbeaver [OP]]

i figured it out... to everyone who helped, thank you for all your effort and suggestions . after i did the last tests yotarunner85 told me to do, i definatly had no power to any of the fuses. i looked for the main source of power which is the hot wire that runs from the battery into the fuse block on the passenger side wheel well, ha it was broken . it took me 15 minutes to fix it. i should have started there first cos its happend to me before, battery tie down comes loose and the battery slams around and breaks the wire and i lose all power. thats what tricked me is that i still had power to a few things. oh well it runs great now so i dont care .

thanks again,
kevin