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Super Mechanic
Super Mechanic, Master technician
Category: Chevy
Satisfied Customers: 17212
Experience:  29 yrs. exp., ASE master, cert. in G.M. electrical, a/c, susspension, brakes, electronic steering
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87 silverado no juice to pump relay orange wire, 90k good

Customer Question

87 silverado no juice to pump relay orange wire
JA: How many miles are on the car? Has the car been starting normally?
Customer: 90k good until now wont start
JA: What is the model of your '87 Chevy?
Customer: silverado c10
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: yes wouldnt start, dump gas in TB runs for a sec,must be fuelpump? no new one didnt run check voltage at pump only 6 hooked both new and old up to 12 volts both spin,
JA: Anything else you think the mechanic should know?
Customer: cant think of anything now
Submitted: 7 months ago.
Category: Chevy
Expert:  Super Mechanic replied 7 months ago.

Hello and welcome. My name is ***** ***** you for visiting the site, I am reviewing your question and will reply shortly, thanks.

Expert:  Super Mechanic replied 7 months ago.

Which engine is in it?

Have you checked the fuses?

Customer: replied 7 months ago.
350 yes, only in fuse block
Expert:  Super Mechanic replied 7 months ago.

I see, thanks. And there is no voltage to the orange wire at the relay? Any voltage at the ECM "B" fuse?

Customer: replied 7 months ago.
would pump relay switch not working ,give only 6 volts at pump no volts at orange wire, dont know where ECM fuse is located
Expert:  Super Mechanic replied 7 months ago.

Not normally but there could just be a feedback voltage of 6v and the ECM "B" fuse is in the fuse box inside the vehicle, they should be marked but if not you could just see if any do only have 6v at them.

Expert:  Super Mechanic replied 7 months ago.

Also, will the fuel pump run with the relay jumped out? (orange wire to tan/white)

Customer: replied 7 months ago.
it has duel tanks, if switch in cab is bad could it cause all the prblems took jumper wire from battery, touched every spade on connector, my helper never heard pump kick in
Customer: replied 7 months ago.
it wouldnt work anyways, no juice at orange wire
Customer: replied 7 months ago.
what exactly does the ECM fuse run, do,and/or control
Expert:  Super Mechanic replied 7 months ago.

I see, thanks. That's what I meant to say, being there is no power to the relay itself and yes, I have seen some of the switches go bad and cause that, aside from the 6 volts to the pump(s). Also the connectors would sometimes start to melt on a couple of them.

There is a test for that.

The ECM fuse powers the fuel pump relay, (orange wire)

Expert:  Super Mechanic replied 7 months ago.

Let me just say that any money that you paid, or if you have a subscription, that money stays in your account until the answers are rated, (positive) regardless of how fast or how long it may take to get finished. You can FOLLOW UP AT ANYTIME, even after rating.

….

I have the test instructions in a PDF format, at the following link. You can copy and paste it into a new browser and rate the answer on this page.

.

https://www.dropbox.com/s/yco9c7q1dcx47pm/fuel%20tank%20switch.gif?dl=0

Please don’t forget to rate the answer in a positive way, . EVEN IF YOU HAVE A SUBSCRIPTION ****THAT IS THE ONLY WAY I GET PAID ****

Customer: replied 7 months ago.
do you know the colors of the wires on the tank switch {4} and wwhich ones I can connect direct for the right tank, I took them off and forgot what goes where
Customer: replied 7 months ago.
fuse is good at ecm b
Customer: replied 7 months ago.
is the wires on the tank switch, all ground wires
Customer: replied 7 months ago.
Are you going to answer my last questions, I need the wiring diagram for the tank switch in the cab on the dash.
Expert:  Super Mechanic replied 7 months ago.

Sorry, I had to run out and get the wife something to eat, I had a bite too, (lol).

I meant to include the diagram(s) along with the test, sorry.

https://www.dropbox.com/s/b34l8oedjbl1hfj/fuel%20pump%20wiring.gif?dl=0

https://www.dropbox.com/s/jt9gtt7yv5chkjo/R_G_P%20fuel%20pump%20wiring.gif?dl=0

Expert:  Super Mechanic replied 7 months ago.

Where did you go?