EFI Fuse Keeps Blowing! Help!

[Robo86]

Good afternoon ladies and gentlemen,

Car - JDM AE86

Motor - 7AGE, Stock loom, all sensors hooked up etc.

Problem - Car keeps blowing the 'EFI Main' Fuse in the engine bay fuse box. The car can sit and be revved at idle, but as soon as it's put under load being driven, the fuse dies within seconds.

Funnily enough it hasnt done it for a week or so (being intermittent), but i need to get to the bottom of it (for obvious reasons).

Possible problems? I have read on some toyota forums that the wiring to the O2 sensor can cause dramas like this, but I have looked over mine and it seems fine, Any leads (LOL pun) are much appreciated!

Cheers DC,
Robo

[driftke70]

positive arching out on something, hows the fuel pump wired and have you had a look at the condition of the wiring if it has an intank pump, sometimes the plastic can perish inside the fuel tank and expose the wire through the insulation.

i dont think a bad plug would do it, also your fuel pump could just be farked and cranking out real high loads that are drawing too many amps, as you are driving and giving it load its probably feeding that bit more current and putting a greater load on the fuel pump, a car needs more fuel at 5k down a street than it does at 5k in your driveway.

[Robo86]

yer man, ill have a dip at the fuel pump if nothing else comes clear. although like i said it does drive/ thrash right now... but it died and now it works... so yer

[sundee]

1st thing to do would be to check that its actually the right amperage

should be a 15 amp fuse.

The EFI main fuse supplies switchable power to the EFI main relay and:

once switched, it then provides power to the Circuit opening relay :

That power once in the circuit opening relay is switched to power the fuel pump.

.. try running the engine and giving each of the above relays a flick and see if the engine dies... sounds like an intermittent fault..

in that circuit 2 wires tap into the feed after the efi main relay but before the circuit opening relay they both go off to the ECU....

[Robo86]

Yea, its defs got the 15 in it. i will try the relay thing. thanks man

[Anthony]

bigport o2 is one wire so cant cause this problem, only later 4 wire types can.

check you didnt squash the fuel pump wiring in the boot between the beaver panel and the pump plate when you had all those engine parts in there.

[Robo86]

Did the relay thing, nothing happened lol.
also checked over the wiring in the boot to the pump, all seems ok. but i will have a better look in the day i guess.

any other thoughts, just let them spill out!

[FAST EDDIE]

i had the same issue, went to 30amp fuse which kept blowing intermitently, is now hard wired!!!

[blair]

^ LOL. love it.

[Robo86]

yer haha rather not hard wire it, i wanna fix it.

had a chat to Ant, he thinks that the wiring/pump itself is shit (or clogged) and therefore the pump is sending too much amperage and blowing the fuse,

will probs drop the tank and clean it, new pump unless some more light comes out in here!