efi fuse blown, out of ideas.... (1 Viewer)

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Aug 26, 2008
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Indiahoma, Oklahoma
i know this has been beat to death, but i'am out of ideas. I have a 87 4runner with the 22R and a auto. Truck ran fine, sat for awhile, not it blows the efi fuse when i crank it. I've pulled and tested the fuel pump, witch is good. Started unplugging harness and whatnot trying to isolate where the short is. I have a ton of stuff unplugged. i did find a short where on the outgoing side of the AM1 and AM2 fuse. I looked at all the harness including the O2 sensor and they seam to be in decent shape. The thing thats got me stumped is i pulled the relay above the radio behind the glove box (A/C relay i think?) and the short goes away to the efi fuse. Also, on the 80 amp black fuse that comes off the battery, theres one wire by it's self, and two wires tied together bolted to the bottom. Does anyone know where they lead off too? I'am trying to explain it the best i can, but i'am sure i left something out.
 

2ndGenToyotaFan

Just spend all the money.....
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The EFI fuse powers the ECU which sends some sort of signal to the "A/C idle up" controller.... If unplugging the AC relay stops it, then I'd look in the AC circuit for your problem....

Check the FAQ here and look through one of the FSM's. There is an 85 and an 88, the 85 manual you can look at online without downloading I think...

* I just looked at my 85, 88 and 89 FSM's and I don't see any black wires coming off of the main 80 amp fuse... they all are shown as white and or red...

Happy hunting! :D
 
Joined
Aug 26, 2008
Messages
39
Location
Indiahoma, Oklahoma
yes, this is quite the easter egg hunt. I got curious today and hooked every thing back up and left the fuel pump unplugged. i cranked the crap out of it and no blown efi fuse. so i pulled the pump again, checked it to make sure it works, even swapped it with another one i had that works, and bam, as soon as i hook the fuel pump up and crank it, it pops the fuse. it's got to have something to do with the pump? all the wires in the pump housing are good, but the pump shows 0 resistance when i check across the terminals. this is what really stumps me, if i leave the fuel line off the pump it will blow fuel all over and not blow the fuse, as soon has i hook the line back up it pops. i unhooked the fuel line going into the filter just to make sure it wasn't clogged and it still pops the fuse when i run it? Any ideas on that???
 

Bogo

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Feb 15, 2008
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What is the ohms reading from the other pump? 0 ohms is a dead short. That will draw as much current as possible which will blow a fuse. What are the fuel pump test procedures in the FSM for the vehicle?
 

pappy

photosynthesizing
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it's got to have something to do with the pump?
I would inspect the fuel pump bracket. I had a clamp short out to the bracket ... by bad. I would also check from the connection coming into the bracket to the wires on the bracket itself. I'll bet there might be a short on the bracket "cap."
 
Joined
Aug 26, 2008
Messages
39
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Indiahoma, Oklahoma
well after some head scratching i got the fuse poping problem under control. i broke down and bought another fuel pump off ebay, put it in and cranked the crap out of it. didn't blow the fuse. I cracked the cold start injector and fuels pumping out. So long story short, all 3 pumps i had laying around would work if i put 12v to them, but must have been pulling too many amps and poping the fuse. i really didn't think it would have done that since they would run, but stranger things have happened. now i have a different problem, for whatever reason i'am not getting any injector pulse.i did hook up a noid light, swaped the ecu, swaped the resistor, have 12v at the injector and i'am getting spark. i'am going to check the grounds and tach tomorrow. seems like my tach would jump when i was cranking it before, but i did notice it wasn't doing anything today.
 
Joined
Aug 26, 2008
Messages
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Indiahoma, Oklahoma
well, i tried to play with it more today, i did try to swap the ecu with the same result. I did do a couple other checks. I have voltage to the ecu, and went through the checks from the fsm. the ecm and solenoid resistor seem to be good from what i see. i did put a noid light on the cold start injector and that is working, so i'am thinking since it shares the same ground point with the main injectors that's good. i have spark, so know the ignitor is good. maybe the rpm signal to ecm????
 

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