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Skyvisions
Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14410
Experience:  Toyota Master Diagnostic
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Toyota Pickup 1991 toyota pickup 2.4L Fuel pump doesnt turn

Customer Question

1991 toyota pickup 2.4L Fuel pump doesnt turn on with ignition key. Relay clicks when ignition is on. Fuel pump can be operated manually and runns.
Submitted: 5 years ago.
Category: Toyota
Expert:  Skyvisions replied 5 years ago.

Thank you for choosing JustAnswer and allowing me to help you resolve your Toyota questions!

 

How are you testing the fuel pump manually? Are you using a jumper wire in the test terminals of the diagnostic check connector box? With the key in the on position if you manually push the mass airflow meter door open from up underneath does the fuel pump run?

Customer: replied 5 years ago.
Yes i am using a jumper wire in the diagnostic box. yes the pump runs if i push the door open
Expert:  Skyvisions replied 5 years ago.
Can you please clarify what exactly is going on? If you want to know why the fuel pump is not running with the key in the on position and the engine is off it is because it's not designed to.
Customer: replied 5 years ago.
Normally when you cycle the key to the on position is primes the pump for 2 seconds. That is not happening in this case. I am trying to start the truck but it will not fire. I am getting spark and have air but I dont hear the pump run so I'm not sure if I am getting fuel while the engine is cranking
Expert:  Skyvisions replied 5 years ago.
That is not how this system works. When you turn the key to the on position there is no power sent to the fuel pump at all. The only time the fuel pump is powered up is when the key is in the start position. At this time power is sent from the starter circuit to the circuit opening relay to energize the circuit opening relay. This causes the fuel pump to run. Once the engine is cranking over i.e. running and you release the starter to the on position the mass airflow sensor takes over and continues the power circuit to the fuel pump. You already confirm that the points in the fuel pump are good because when you push the door open you said the fuel pump runs. You need to confirm whether not you have good fuel pressure at the fuel rail. Is the check engine light on with the key in the on position? Are you getting good ignition spark? Have you checked for injector pulse?
Customer: replied 5 years ago.
That is good to know. I have good ignition spark. I do not have a meas to check pulse or fuel pressure though.
Expert:  Skyvisions replied 5 years ago.
All you need is a test light or a peanut bulb with little wires sticking out of the end to insert into one of the connectors going to the injector. As far as checking fuel pressure you can remove the fuel line going to the cold start injector and stick it into a Coke bottle or plastic container and crank the engine over or open the mass airflow sensor To power up the fuel pump you should have lots of fuel pushing out this line. Use caution when working with open fuel under the hood with electrical sources. What about the check engine light with the key in the on position? Have you checked for any codes that may set in the engine control computer?

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