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EFI fuse blowing after sparkplug wire disconnect

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EFI fuse blowing after sparkplug wire disconnect

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Old 11-20-2016, 10:26 AM
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EFI fuse blowing after sparkplug wire disconnect

1995 4runner 2.4L 22re

Driving down the highway truck starts bogging down gas pedal isnt responding I pull over and it dies, turn it over it cranks but no start, look under the hood and one spark plug wire has come loose, and the EFI fuse had blown, so I put the sparkplug wire back on the spark plug and replaced the fuse, turn it over and boom another fuse, check the truck out, notice the o2 sensor is dangling against the exhaust pipe, wires are fine it had just broke loose, so I zap strapped it back into its position in the pipe checked the wiring was fine, boom another fuse still, at this point I notice i just turn the key to power or on position and thats when it's blowing the fuse before I even crank it. I check the relays under the dash behind the kick panel that are not labelled but is the exact same as the EFI relay which is in the under the hood fuse box, I switched it out with the starter relay because it's also the same as that one and it didnt turn over, leading me to believe that relay is toast.

So my question here is, would a spark plug wire coming off while driving cause the EFI fuse to blow and also this relay under the dash? which and replacing these could possibly fix the problem?
or maybe its related to the fuel pump also? right now just stuck on the side of the road in a small town and its sunday so have to wait untill tommorrow to get a new relay and test my theory
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Old 11-20-2016, 11:43 AM
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Red face

Some place in the o2 sensor harness you might have wires shorting

Since the o2 sensor is powered via the EFI fuse

That is why the fuse continues to open

And it also might have caused the relay to fail as well

Since the EFI relay also feeds the contacts in the Circuit opening relay the fuel pump will not turn on either .

Now if the fuel pump is shorted it will also cause the EFI fuse to open

You have some trouble shooting to do .

The spark plug wire falling off was just poor timing or bad luck
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Old 11-20-2016, 12:03 PM
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can I unplug the o2 sensor at the harness? does it have to be there in order to run the truck?
Fuel pump is something I have not checked into yet :/ but say it was a bad fuel pump, would it blow the fuse / relay before the engine is cranked over, like blowing the fuse when the key is just turned to the on / power position?

also I can't test to see if the fuel pump turns on because as soon as i turn the key to on the fuse blows, usually when I've done this before it won't blow the fuse and you can hear the fuel pump come on but it just wont crank over because it's not working properly but it didnt blow any fuses before.

Last edited by wildman ben; 11-20-2016 at 12:14 PM.
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