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 AMEDEE Your Own Question
AMEDEE
AMEDEE, CHEVY TECHNICIAN
Category: Chevy
Satisfied Customers: 25624
Experience:  ASE certified tech ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
279429
Type Your Chevy Question Here...
AMEDEE is online now
A new question is answered every 9 seconds

Fuel pump not coming on, original as far as i know. had it

Customer Question

fuel pump not coming on
JA: Have you ever replaced the fuel pump, or is this the original?
Customer: original as far as i know. had it for 6 years
JA: What is the model/year of your Chevy?
Customer: 98 jimmy
JA: Are you fixing your Jimmy yourself? What have you tried so far?
Customer: i pulled the fuel pump relay. jumped pin 87 to 30 no go. test light to pin 30 to ground lites up. pin 86 has power when switch on.. yesterday when jumping 87 to 30 nothing. today 87 to 30 pump came on. put relay back in worked . turned vehicle on and off a few times and it. then it quit again. any ideas /
JA: Anything else you want the mechanic to know before I connect you?
Customer: no i dont think so
Submitted: 7 months ago.
Category: Chevy
Expert:  AMEDEE replied 7 months ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Expert:  AMEDEE replied 7 months ago.

Does the check engine light come on with the key on?

Can I start by getting your VIN?

Thank you!

Customer: replied 7 months ago.
No. 1GKDT13W9W2560311
Expert:  AMEDEE replied 7 months ago.

Thank you for the VIN!

IT looks like the vehicle control module powers up and or activates the fuel pump relay. I would be willing to bet if you checked into this, the computer is not awake with the key on. This explaines why the fuel pump relay is not getting activated and the check engine light does not come on with the key on.

Have you checked for codes in the computer?

Customer: replied 7 months ago.
no there are not any codes
Customer: replied 7 months ago.
as i was saying it worked for a short time today. but fuel pump was very loud
Expert:  AMEDEE replied 7 months ago.

Are you sure the fuse is good? It might be possible that the fuel pump is pulling too many amps which can blow the fuse.

At the relay, remove it and check for two powers and one ground while cranking. You would check this with the relay removed and checking the female pins (where the relay plugs into). There should be two powers and one ground going into the relay. Here is a wiring diagram.

Customer: replied 7 months ago.
pin 30 had power also pin 85 with switch on
Customer: replied 7 months ago.
swapped out relay
Customer: replied 7 months ago.
ecm b had power across it
Expert:  AMEDEE replied 7 months ago.

My diagram does not tell me which pin is 30 and which is 85.

I will need to know if there is constant power to the relay or if you only get the "key on" power

Customer: replied 7 months ago.
power to key-switch and power from fuel pump pin 30
Customer: replied 7 months ago.
85 is control power
Customer: replied 7 months ago.
it comes on for 2 seconds
Customer: replied 7 months ago.
4=30, 2=85 i can feel relay switching
Customer: replied 7 months ago.
i assume pin 86 is ground
Expert:  AMEDEE replied 7 months ago.

Oh, excellent! So if the fuel pump relay is clicking when the key is turned on and while cranking, then this means the fuel pump relay is getting all of the correct inputs. So then your next step is to check for power at the fuel pump itself on the gray wire. If there is power and the fuel pump has a good ground but still not coming on, the fuel pump is bad and will need to be replaced.

Expert:  AMEDEE replied 7 months ago.

However, if there is no power to the fuel pump on the gray wire, then there is an open in the wire from the relay to the fuel pump. You could trace the wiring and find and fix the issue or simply run a new wire and you will be good to go!

Customer: replied 7 months ago.
if i have power at pin 4 which is fuel pump pin then i should assume bad pump. haven't checked at fuel pump itself
Expert:  AMEDEE replied 7 months ago.

YES, thats correct.. provided the wiring is in good shape. However, that is not very common as the fuel pump itself goes bad all of the time.

Expert:  AMEDEE replied 7 months ago.

I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "5 STAR SERVICE" for assisting you today.

Keep in mind, we can still continue this conversation at no further cost to you even after you rate my answer. Just reply back to me using this page and I will get it and get back to you ASAP!

Please let me know if you have any further questions.

Customer: replied 7 months ago.
ok. that is what i thought. was curious why it worked for a while then quit again
Customer: replied 7 months ago.
thanks
Expert:  AMEDEE replied 7 months ago.

Because it is simply starting to go bad. :)

Your welcome.

Customer: replied 7 months ago.
ok thanks and good nite
Expert:  AMEDEE replied 7 months ago.

Thanks and have a great night!

Please dont forget to rate and please let me know if you have any further questions.

Customer: replied 7 months ago.
ok
Expert:  AMEDEE replied 7 months ago.

You should see the rating system towards the top of the page.

Expert:  AMEDEE replied 7 months ago.

Did you have any further questions?

Expert:  AMEDEE replied 7 months ago.

Hello! It'sCustomerfrom just answer.

I am just checking in to see if you need any further assistance?

Let me know!

Customer: replied 7 months ago.
if i need further assistance i will contact you.
Expert:  AMEDEE replied 7 months ago.

Are you happy with my service?