How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tim's Auto Repair Your Own Question
Tim's Auto Repair
Tim's Auto Repair, Mechanic
Category: Car
Satisfied Customers: 15926
Experience:  Have owned a repair shop for 25 yrs.
Type Your Car Question Here...
Tim's Auto Repair is online now
A new question is answered every 9 seconds

fuel pump relay..crank..Fuel pump would other wise not engage from pcm

Resolved Question:

Truck stopped en-route. Basic trouble-shooting confirmed that if the fuel pump relay is by-passed the pump engages but the engine still would not, although it did crank. Fuel pump would other wise not engage from PCM
Submitted: 6 years ago.
Category: Car
Expert:  Tim's Auto Repair replied 6 years ago.


please explain,,,,does the fuel pump come on for 2 seconds when you first turn the key on?

tell me how and when it started doing this?

do you have any codes in the computer?if so,please give me the codes


Customer: replied 6 years ago.

Here it is. No 2 sec blast. No pump. But, if the pump is by-passed at the fuel pump relay, it will run, although the engine won't engage. What if any, conditions must be met to satisfy the PCM to tell the Fuel Pump Relay to pick-up? and could that possibly be why that even though the pump has been by-passed, the vehicle won't fire.

At this point I'm not interested whether or not pressure is at the fuel rail. Why won't the PCM tell the Fuel Pump Relay to pick-up?

Expert:  Tim's Auto Repair replied 6 years ago.


make sure you don't have any blown fuses.....but

sense it don't come on for the first 2 seconds,,i would think the computer itself is bad...the reason it wont run when you jump the because it don't have an injector pulse..the computer should always energize the relay when you first turn on the key


Please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.if i have sent any diagrams,please print them.they will only stay on here for an hour or so.PLEASE ASK IF YOU NEED MORE HELP


Tim's Auto Repair and 6 other Car Specialists are ready to help you