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Ask Chris (aka-Moose) Your Own Question
Chris (aka-Moose)
Chris (aka-Moose), Auto Technician
Category: Toyota
Satisfied Customers: 814
Experience:  16 years of experience
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I have a 1988 Toyota pickup 3.0 v6 the fuel pump only runs

Customer Question

I have a 1988 Toyota pickup 3.0 v6 the fuel pump only runs with the fb and +b jumper wire in the dignostic port.... Any ideas.... Truck runs fine as long as jumper wire is in place once you remover the jumper the fuel pump stops
JA: Have you ever replaced the fuel pump, or is this the original?
Customer: Have you seen this problem before?
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: It has a new fuel pump... And new open circuit relay
JA: Anything else you think the mechanic should know?
Customer: Yes I am trying to fix myself... It is getting no fuel not unless you bypass it by jumping through the dingnostic port... Then the pump will run it will run fine then.... I have replace injectors, computer, mass air flow, fuel pump, open circuit relay, cold air injector.... Idk
Submitted: 4 months ago.
Category: Toyota
Customer: replied 4 months ago.
Any ideas?
Expert:  Skyvisions replied 4 months ago.

Do you still need help?

Customer: replied 4 months ago.
sir
Customer: replied 4 months ago.
It will run with the b+ and fb jumper in the digonostic port.... Once you remove jumper it will not run
Expert:  Skyvisions replied 4 months ago.

Place your hand on the circuit opening relay. Make sure the key is in the on position. Have somebody lift the top of the air cleaner up so that they can reach their hand up inside the mass air flow meter. Have them push the mass airflow door open about 1/2 inch does the circuit opening relay click on and do you get fuel pressure?

Customer: replied 4 months ago.
It will run if you take your hand and press the mass airflow flap in and out.... It's running at an idle
Expert:  Skyvisions replied 4 months ago.

So just to clarify if the jumper wire is removed from the fuel pump and B+ connection and you hold the mass airflow door open slightly the truck will idle? If this is the case did you make sure that the induction boot is not cracked or broken it's very common for that large rubber boot to crack and not see it and it will suck air and not open the mass airflow door. I have two make a run to the store for the Mrs. I will be back and look into the wiring diagram to see what's going on here.

Customer: replied 4 months ago.
this is correct that the jumper wire has been removed and that it will run with my hand placed in the mass airflow sensor.... I've replaced the tube from the mass airflow to the ram with a new one... Wiring? Maybe... Do you have a schematic?
Expert:  Skyvisions replied 4 months ago.

When you push the door open and the mass airflow sensor does it appear to have the same amount of resistance the entire way is pushed open? Does it seem a little heavier to push open when you first start to move the door? It's not likely electrical problem otherwise you would have a code set in the computer. The contact points in the mass airflow meter activate the fuel pump once the key is released from the start position and the engine is cranking over. If you listen carefully how far does the mass airflow sensor have to be pushed before the fuel pump/circuit opening relay activate?

Expert:  Skyvisions replied 4 months ago.

What is the color coding of the of the wires going to the mass airflow sensor? Carefully pull back on the rubber boot that goes to the connector. I just want to verify have the right wiring diagram. Also check to make sure none of the wires are broken I have seen where the wires will break off the end of the pins in that connector right inside that rubber boot.

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