so i have been driving my truck the last three weeks and havent had any problems with it, until yesterday was driving down the road and it died and wouldnt start. Got it towed home and realized it blew the 15a efi fuse, put a new fuse in it and it fired right up and was running good again. Well today i drove it around town and it was running good tell i hit the highway and then the fuse blew again. now whenever i put a new fuse in it and try starting it, the fuse blows right away. Anyone got any idea of what it could possibly be, i am hoping it isnt a short somewhere but right now that seems like what it might be.

 

Faulty wiring somewhere. Search "efi fuse" and you'll get tons of different threads with different places of faulty wiring that have caused this same exact symptom.

 

Common cause is for the wires running from the O2 sensor falling against the hot exhaust and causing the insulation to melt.

 

x2

 

Also check the wiring harness behind the dash where the e-brake is.

 

and get a breaker instead of a fuse for while your testing that way you dont go through 40 bucks worth of fuses a you can get a 15 or 20 amp breaker that will auto reset like 5 seconds after it blows so you can try trial and error with out having to go through a billion fuses they had one at schucks auto supply when i had that problem

 

it was the o2 sensor wires, they were touching the side of the exhaust pipe got the problem fixed. thanks for all the help

 

no prob thats exactly what happened to my now sold 91 standerd cab good to hear thats all it was

 

Check the o2 first then if thats not the problem, then try the MAF, my 89 was doing the same thing, unplug the o2 and see if the fuse blows, I did this for everything connected to the EFI fuse and found out it was the MAF, now i got one out of a 86 toyota motorhome!!!

 

Fuses are free in the junkyard