Hi, I own a 96' 4x4 3.4L Ext. Cab T-100 and it WILL NOT STOP BLOWING THE EFI FUSE! Before, it seemed as though the fuse blow time to drive ratio got smaller as the engine got hotter. In otherwords it would drive for a couple miles, blow a fuse, replace the fuse drive a mile blow fuse, replace fuse drive a couple hundred feet blow fuse..... My mechanic told me to disconnect one of my o2 sensors to see if that was the issue. Long story short, I disconnected my o2 sensors to see. Once i disconnected the o2 sensor in front of my CAT, truck will start and blow fuse after 5-10 ft of driving, then i replace fuse, truck drives forever. I'm talking like 30 miles if I wanted to. WTF!? any answers? or people with the same issue?

Sounds more like you have a wire that is grounding out and causing a short circuit. I would do a close visual inspection of the wiring and look for any chaff or rub spot.

The fuse is in the smart junction block? What is amp rating of fuse? My thought, for testing, use a new wire for proper wire color with inline fuse at sjb to rear lamp. I looked at wiring diagram, appears to be more than one fuse, don't know which one is blowing, the amp rating would help. I can only help with testing.

check for a dead short in starter relay , wiring etc after the fuse

you may have a short of some kind, when a fuse blows repeatedly it is no good just replacing, you are being told that something is wrong with the equipment.
You will almost certainly have to visit a technician for a diagnosis. It is unlikely to be something that an inexperienced end user can sort out I am afraid.

GOOD LUCK

there is a short in a unit or wire that the EFI unit runs. It may even be in the EFI unit itself. Insert a new fuse and run the fault codes to determine if a fault has been recorded.

I have a 2004 Sorento EX and my EXT fuse along with the stop lamp fuse kept blowing. The ext would blow as soon as I turned the vehicle on. The stop lamp would blow after a couple pushes of the brake pedal causeing me to have no rear lights at all regarding brake and the lights that you turn on at night. After much reading online in forums such as this, I was led on a chase looking for grounding wires, broken wires, dirty battery terminals, faulty altinator, and for a drl module. I could not find a drl module as I now do not believe there is one in sorentos, or at least in mine. I then came to the brake switch that is located on the arm of the brake pedal. I disconnected it, put a couple of new fuses in, started my vehicle and checked my fuses, and at last they did not blow! I reconnected the brake switch and checked the fuses and they had blown. I have a hunch that I am dealing with a faulty brake switch. Hope this helps

Hi Jeff , in what fuse box is this 10 amp ign. fuse located ? I am looking at a power distribution diagram and i see a IGN 3 10amp fuse located in the I/P fuse box ! Is this the fuse that blows ? I see where you replaced the 10 amp with a 30amp . That is never a good idea , you don't want to make your problems worst . Melt wiring harness , could start a fire . Do you know how to do electrical trouble shooting ? How to use a wiring diagram , power distribuition diagram ? That fuse is hot in the run , powers the rear Heat / A/C , automatic level relay, ESC - electronic suspension control module , rear wheel steering control module , Plus someother thing's depending which vehicle , Y91 - ULT . Your Taho doesn't have all this options . http://www.bbbind.com/free_tsb.html find the thing's that fuse powers , disconnect them one at a time till the problem goes away .

I had the same problem with my 1990 P/u. It turned out to be the O2 sensor touching the underside of my box shorting and blowing the EFI Fuse

i had the same problem on time i had a o2 sensor melted to exhaust behind cab and fuel pump wires were loose i fixed the wires and put in new fuse and started right up

The most common reason for the EFI fuse to blow is the wiring is rubbed through somewhere in the engine wiring harness, this fuse supplies power to many EFI parts on the engine, always look for shorts where the most movement is, the engine is that place, most likely the next time you go down a really rough road the short may occure again, carry a few fuses just to be safe.