my efi fuse ,15a, is popping. i have replaced the fuel pump and fuilter,fixed the upstream o2 sensor but it still pops. The troubleing part is that when i kill it it will pop, stopping the fuel pump. any ideas.
p.s.
this is a 1997 Toyota rav4, picture comming soon.

 

Ok new update it did progress to a random blowing of the fuse I'm trying to replace the main relay! Here's hoping!

 

Most of the time you have a fuse blowing, it is because the power wire is shorting to ground prior to the load (the component) being powered in that circuit. Usually that is caused by a loss of insulation for that wire.

What you can do is rig up a spare 12 volt headlight or even a 12 volt buzzer and connect it into that fuse contacts. Then start wiggling wires to see if the buzzer sounds or the headlight turns on. Then you have narrowed down where to look for a short.

What happens in a short-to-ground, is that battery voltage immediately goes to ground without any resistance that a load would provide. No resistance means high amps. High amps means that the fuse blows to protect the wires.

The other time a fuse blows is because the component is drawing (pulling) to many amps. That's usually caused by a component failing.

 

Good idea!

 

I had that problem I used replace the fuse like every 7-10 days and it really got toasted but I kept running the truck for months till one day I checked my timing and found out the tps needed to be replaced.After changing out the tps so I could set my timing the popping efi fuse stop and has been good since.