99 blazer, stalling, blows 20amp fuse

[skooterbum]

i apologize if this is the wrong section to post this. my problem is, my 99 blazer shuts down while i am driving. it has happened 2 times so far. each time this happened i was at a stop in traffic. when it was time for me to go, i would accelerate from the stop, then get half way through the intersection, and the engine stalled out. both times this happened i found the 20amp fuse, next to the big fuel pump fuse in the engine compartment, had blown. if i let the car set for 20 minutes, and replace the fuse, it starts right up and runs fine. i put about 400 miles on it between the first time it blew the fuse and the second time. the engine was at full operating temp both times. it has the v6 4.3 with 108.000 miles. something is getting ready to go on this car, and i am hoping that it is not the fuel pump. i am not ready to put $1,000 into this right now. is there any other part on this that could be causing this to happen ?? i did replace the fuel filter a year ago.
any advice / suggestions will be appreciated !!!!

thanks
Ron

[old_master]

What fuse is blowing? It should tell in the owners manual or on the underside of the fuse panel cover.

[skooterbum]

hey old master, i have a haynes repair manual. in the manuals fuel & exhaust systems chapter, there is a note about fuses that are tied into the fuel system. there is a ECM BAT fuse in the fuse center that governs the fuel pump relay, the fuel pump, the injectors, the ignition system and the PCM. that is the 20amp fuse that has been blowing on me. as you are leaning over the left / drivers side fender, there is a fuse panel inside the engine compartment. there is a large [large for a fuse] box type fuse for the fuel pump. the 20amp ECM BAT fuse is on the left, top, side of the fuel pump fuse. any ideas where i need to start to look for problems with this 20amp fuse blowing ?? i am very ignorant when it comes to electrical problems. so i am thinking if this isn't a straight forward problem to fix, that i am going to have to put it into the shop. i would like to know what is going on, so if i can't fix it, i at least know about the problem and can lead the repair shop in the right direction to hopfully save me some money.
thanks
ron

[old_master]

Intermittent short circuits can be extremely difficult to locate and require tons of patience. Each sub circuit powered by that fuse will cause the engine to stall: fuel pump, injectors, PCM, ignition, etc etc, which means driving the vehicle with a fuel pressure gauge connected, or something to monitor ignition, will not be conclussive, you already know they both quit. Testing can only be done when the problem is present by removing sub/spur circuits until the short is no longer present. I'd start with a good visual inspection of the wiring.

[viggy58]

this just happened to me...ecm 1 fuse blew while driving.

unhook the neg terminal of the battery, then completely unbolt the fuse/relay center (under the hood). 7mm socket will release the harnesses on the bottom enough to unhook the covers. check every wire for any pinching / stripping.

check the thread on "free repair manual"... i posted a link to a 97 service manual. mine is a 2001, but the diagrams and wire colors were the same. find the wires from the fuse that is blowing and make sure there is no damage. wiggle them, to make sure that doesnt cause any faults.

the cause of mine was a wire that was pinched. i hit a bump, which caused just enough force on the fuse/relay center to pinch a wire (ecm 1 fuse) enough to ground it out and blow the fuse. had no spark or fuel pump power until i repaired the fuse AND wire.

[skooterbum]

thanks viggy58, that's a good idea, and a good place to start. weather permitting tomorrow i will do as suggested and post the results.
thanks
ron

[Westell]

I had this same problem awhile back Old master helped me a lot on the problem. My vehicle is older 95 little different than yours. It only did it under load any gear on the gas. I finally found the problem i had a broken motor mount which was causing my wiring to be pinched behind the OPSU. Very hard to find but i haven't had the problem in moths now. If its only doing it when your giving throttle may be worth looking around for the same problem.

[skooterbum]

thanks westell !!! i will check for a broken motor mount too. it makes sense that a motor mount might be broke with the symptoms that i am having. finding a broken motor mount...easy, finding electrical problem.... #^&&%#@#( !!!!!!!!!
thanks
ron

[skooterbum]

hey westell, if you see this, you was right on the money. i found that my left side motor mount is broke. i also found a wire loom that runs under my air cleaner assembly was rubbing on a metal bracket and shorting out. i fixed the wire problem easy enough, but am putting it in the shop to fix the mount. this should fix my fuse blowing problem. thanks for the help guys.

[viggy58]

thanks for posting back! let us know if that fixes it.