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Old 04-24-2011, 08:21 AM
willyjpeters willyjpeters is offline
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Default still no fuel-fuel pumps?

i have an 87 ranger with front/rear tanks, and apparently a low pressure pump in the tank and a high pressure in the frame. i have checked everything in the engine compartment, relay is new and power to the relay, but no pump turn-on noise when the key is turned. before i go checking wiring under the frame to the pumps, which you know is a real pain, is there anything else that i can check? i seems odd that none of the pumps seem to turn on, but would that be normal if one pump is bad that all quit working? thanks
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Old 04-24-2011, 09:04 AM
mickblock mickblock is offline
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Default Re: still no fuel-fuel pumps?

check for your 12v at the fuel pumps harness head then check ground continuity. There's your wire checks in a handbag. You just have to undo the tank straps and a couple lines and give yourself enough access to the top by letting he tank be supported on a couple jack stands

If you get + results load test the fuel pump itself by backprobing the +/- while the connector is attached to the pump and turn the key. but hell if the harness head is good for 12v/ground and the pump doesn't turn on what else could it be.
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Old 04-26-2011, 12:13 PM
Psychopete Psychopete is offline
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Default Re: still no fuel-fuel pumps?

Quote:
Originally Posted by willyjpeters View Post
is there anything else that i can check? i seems odd that none of the pumps seem to turn on, but would that be normal if one pump is bad that all quit working? thanks
There are a couple of checks you can do, but you really should be referencing an EVTM on this one. The circuit is simple, but too much work to describe in a way that it's easier to understand in words than it is to just look at the schematic.

On my '88, I found an undocumented plug on the driver's side near the firewall, follow the power wire from the frame mounted pump up - there you can apply 12 volts directly to the pumps to test, and/or put a test light on that to help determine where the voltage drop is.

'87 is going to have fuse links. The fuel pump relay is also controlled by the computer. You need to verify that the computer is working. I would start at the fuel pump relay and check fused power (yellow or yellow black or black and yellow - I don't know your specific config off the top of my head). Check the red wire for +12v when the key is on run - this is powered from the computer relay. The other is power to fuel pump and the other is ground from the computer that turns on the relay. I can't remember the specific colors though. You will need to find that out as I am too lazy to, and quite frankly it's not my truck to diagnose.

The diagnostic connector also has a fuel pump test, which you supply a ground to one of the terminals. This supplements the ground from the computer that controls the relay to be on all of the time. Look on images.google.com to see which terminal it is as there would be confusion if I tried to type it out in words.
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