Engine fuse keeps burning out?

[Al Johnson]

Does anyone have any idea what all is wired to the engine fuse? on the fuse block? I think it is my Idle Solenoid that keeps shorting out and then the engine won't run. I put a new fuse in and it runs for a short period of time then burns the fuse out and will not idle - anyone have a clue ? any help would be fantastic as this is my every day driver and driving with one foot on the brake and one on the gas is getting a little old!

 

[spotcruiser]

What year? Ah, 1980 based on your garage listing?

You should get a wiring diagram.

On a 78, you have the idle solenoid, V/R IG input, emissions controls, and carb cooling fan. If your's is an 80, it should be pretty close (perhaps different on the V/R input).

 

[DSRTRDR]

is the fuse seat itself intact ?

I had a broken tab and that blew out the fuse several times

 

[Al Johnson]

My FJ40 is an 80 - that would make sense because my carb fan isn't working either. I will check harness probably some kind of short in that part of the harness.

 

[Al Johnson]

Yes fuse block is intact, I am going to disconnect bat and strip harness and look for short ....

 

[Pin_Head]

The most common short on this circuit is the idle fuel cut off wire where it runs along the top of the head on the air injectors. The heat burns away the insulation.

 

[Al Johnson]

Thanks, will crawl around inside and see what I can find - hopefully it just some burnt off insulation.

 

[Al Johnson]

Well checked out wiring on Idel solenoid and unhooked it, still pops fuse after running for short time - at my whits end .....starting to cut the loom apart to trace the wires . one goes into the ECM the other I am still tracing black with yellow stripe. any one have any ideas ????

 

[spotcruiser]

You're looking for a replacement harness because you keep blowing engine fuses?

Disconnect your carb fan controller and disconnect your carb fan to see if that solves the issue. You might also want to look at the carb fan temp sensor wire below the intake manifold, as I've seen those burned/rusted off and hanging free.

You do have the stock grommets where the harnesses pass through the firewall, right? It always bothers me to see wires passing through bare holes.

 

[Al Johnson]

I Will disconnect carb fan controller and carb fan and see if this works. stripping wire loom now to trace all wires to see if something has rubbed off. I do have a grommet through the fire wall and is still good. To be continued - the search continues.....

 

[Pin_Head]

A better strategy is to be systematic:
1.Disconnect everything that is on this circuit.
2. Remove the fuse and connect an amp meter across the lugs for the fuse in the fuse block.
3. Check for current flow. If there is no flow, the wires are not shorted to ground. If there is flow, either you forgot to disconnect something or there is a wire short. If the current is high (maybe 5A or more) then it is more likely a wire shorted. Follow all the wires and pull on them to see if the current drops.
4. If there is no flow, connect each device one at a time and measure the current. If you see a big current jump, then chances are that the device you just connected is shorted.

 

[Coolerman]

If you don't have an amp meter then solder two wires to a tail light bulb and clip those across the fuse terminals. If the lamp lights brightly there is at least 1.4 amps flowing through the circuit. The bulb acts as a resistor allowing you to leave it connected while you troubleshoot. 1.4 amps is not enough to melt wire insulation. Keep wiggling stuff until you see the light go out and you have found your short.

 

[Al Johnson]

Hot Hot Hot Damn ! I fingered it out ! What a bitch ! kept burning out engine fuses and could not figure it out put a fuse in it would idle alright for ever then if you accelerated it would pop the fuse ----- what the Hell ! tore all of the wiring apart and checked every thing I could - disconected every thing I could still blew fuses - traced everything and (REGULATOR) burnt wire.......damn took it apart and low and behold there it was heated up and blew the fuse........cut a piece of 16 and soldered it to the regulator !BINGO! THE MILLION DOLLAR EVER LASTING CHASE IS OVER ! Thank you alll

ON THE ROAD AGAIN --- THANK YOU ALL!

 

[bparker]

having a similar problem on my '75. alternator is not charging the battery. amp meter is reading less than half at all times and when i cut on the lights or use blinkers it falls drastically. basically im running on batter only. engine fuse blows as soon as the key is turned in the on position. new voltage regulator and alternator but neither is getting power because of the fuse blowing. could someone elaborate on what specifically runs through the 'engine' fuse? i just need to check off everything because there is an obvious short or bad wire somewhere i guess. thanks for any help.

 

[bparker]

i shouldn't say that the alternator isn't getting power--it is, but it is around 12.5 when it should be much higher. it's only showing the power from the battery

 

[edwjmcgrath]

Look here for a schematic for your 75.
There are only a few items on that circuit.
Voltage regulator, maintenance interval detector, idle solenoid, emission computer.

http://www.globalsoftware-inc.com/coolerman/fj40/schematics/

 

[websterrd]

i shouldn't say that the alternator isn't getting power--it is, but it is around 12.5 when it should be much higher. it's only showing the power from the battery

Did you ever figure out why the fuse kept blowing. I am having the exact same issue with my ‘77