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Old 05-16-2009, 05:23 PM   #1
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fuel pump relay issues

My buddy has a 1988 toyota rv with the pickup cab. It is the 22RE motor. The fuel pump relay is only putting out 10.3 volts to the fuel pump. We already tried a new relay and it is the same thing. Anyone know what the problem could be?

He drove it out to another friends house and the next morning it wouldnt start. Cranks fine and has spark but I believe the problem is the voltage to the pump. It should be at 12 volts correct? Any help would be very appreciated
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Old 05-16-2009, 06:13 PM   #2
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Trace the circuit from the pump back and see where the voltage drops:
- http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

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Old 05-17-2009, 09:40 AM   #3
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Ok so I believe it is a problem with the VAF meter. I tested the COR and it tested ok as far as having continuity in the correct spots. When I tested the air flow meter one of the tests showed a different resistance than was supposed to be there. I never knew that a a fuel pump switch would be built into a MAF like that. Gonna rig a switch to the pump just to get the rv back to our house and then replace the VAF.

Anyone else have any good suggestions? Thanks for the help so far!

Also does anyone know of a forum more specific to "micro mini" rvs?
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Old 05-17-2009, 12:34 PM   #4
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Just use the built-in fuel pump test jumper. I added a switch for mine:

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Old 05-17-2009, 08:59 PM   #5
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Ok did the test jumper and it still doesnt get the full 12 volts.
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Old 05-17-2009, 09:34 PM   #6
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Well, then trace back the circuit with a volt meter and see where the voltage drop is coming from. After all, you have 12 volts (or whatever) at the battery and something less at the pump. Some place between those two points, the voltage must drop.
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Old 05-19-2009, 09:29 PM   #7
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Ok so what i have figured out is that i am getting only 10 volts during crank and 12 once actually running (still rigged). Could it be a bad ground or starter/ignition issue? I am at a lost right now.
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Old 05-20-2009, 07:50 AM   #8
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Well 10 volts while cranking sounds decent. The starter motor will of course pull the voltage of the battery down due to it's high current demands. And 12 volts while running may be OK. What is the battery voltage at the same time? If the pump voltage is significantly less than the battery voltage, then start measure the voltages along that circuit and find out at what point does it drop. The work back to isolate the cause of the voltage drop.
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Old 08-05-2010, 07:02 AM   #9
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Relays used in the diagram

I am wondering if you happen to know the part numbers of the relays in the wiring diagram, and possibly which one is the most purchased? I have an 86 4 Runner that is having starting issues when hot, and just yesterday cut off on me while driving - the first time that has happened - and I was actually starting off from a stop, so I think it got too hot while idling. Regardless, a well intentioned guy I was talking to mentioned the same thing happenend with his Ford and it was the relays. I have already replaced the coil and the fuel pump - advice I took from reading other posts, and don't have the gear to check all of the volts, etc on the wires. This is my daily driver so I need to get her consistently working.
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Old 08-05-2010, 07:02 AM
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22re, 93, drops, fuel, issues, jumper, location, motorhome, pickup, pump, pumprelay, relay, testing, toyota, voltage

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