1989 s10 blazer, 4.3, 4x4. Was driving down the road when it shut of. Engine would turn over, but would not start. Towed it home. Started troubleshooting the next day. Noticed I did not hear the familiar hum of the fuel pump when first turning the key. Suspected fuel pump... but...

Parking lights and turn signals work. Headlights do not.

Dome light and glove box light do not work, but map lights on rearview mirror do.

No dash lights.

Horn does not work.

Power locks and power windows still work.

Push button release for back hatch does not work. This actually happened right before the fateful voyage, so I used the key to unlock the hatch, loaded up, and took off. Have not yet determined if this is relevant, but appears to be the first problem.

Radio will not display time or tune a station, but will produce static when turned on.

Blower fan for heat/defrost will work on lower settings, but will shut off when turned to highest setting.

Replaced fuel pump relay and fuel pump/sending unit.

Checked all fuses in fuse box under dash. None were blown.

Checked for error codes. Not showing any. I do get the confirmation code that the tester is communicating with the computer.

Checked battery terminals. They were clean, showing no signs of corrosion, but I cleaned them anyway.

Acting on a tip from another member, I checked the two negative cables coming off the battery, one to the engine block, the other to a bolt next to the back of the passenger side headlight. They did not show any signs of corrosion or being loose, but I cleaned them anyway.

Ignition module was replaced last year. Similar symptoms - Engine would turn over but would not start. However, when that happened, I had power to the fuel pump, but no spark at the plugs. This time around, I have spark at the plugs, but no power to the fuel pump.

Not that it matters, but I replaced the gas tank when I replaced the fuel pump/sending unit to avoid having to do it later on down the road. It was original and in bad shape, and I'll be in no hurry to drop that tank and mess with those connections again.

At the electrical connector leading to the gas tank, I have power to the fuel gauge, but not to the fuel pump. It also appears that where the ground wire from the tank is attached to the frame, that location is not producing a ground even after wire brushing the frame, bolt, and eyelet at the end of the wire. I can get the fuel pump to pump fuel if I attach a 12 volt power source to the hot wire and a seperate ground going directly to the negative terminal of the battery. I still was not able to get the engine to fire with it hooked up this way, but that could be due to engine flooding in the time it took me to make the connection, crawl out from under the vehicle, get inside, and turn the key.

I have been troubleshooting this for nearly two months. Zoning is very strict in my area, and as I expected, I have now received my first warning. I really hate to scrap the Blazer, especially since I have a feeling it is some module/relay/sensor that is causing the problem. Any tips, hints, opinions, etc. would be greatly appreciated. Thank you.

 

Not sure if you know this but you can get access to wiring diagrams from the Autozone website. After singing up for a free account you can use the diagrams to trace each problem. ~goodluck~

 

Sounds like you had a short I also have a similar problem. I'm currently tracing the problem. Check if you have power supply to the fuel pump relay the Orange should be hot as far as the wiring diagram goes if you don't have current there the problem is that supply, which I think may be from the ecm? Or a fused circuit?

 

Look at the thick wires doing from your alternator to the harness, not the one that goes to the battery. They should have thick plastic insulators about an inch long on them and on yours they probably have two fuse links into one eyelet that hooked up to the alternator. I had the exact problem with mine but you also have to find what caused the short before you can just replace the fuse wires. Let me know what more info you get.

 

Did anyone have a solution for this problem? Im having the same promblem now! Thanks

 

Hello rmitch. I tried all the suggestions I could find on this site, but nothing corrected the problem. I also took out the interior and traced each wire looking for a pinched wire or a wire where the insulation had worn away and exposed bare wire. I once had a problem caused by a wire that had been pinched when the steering column had been installed at the factory. Over the years, the friction on the wire caused by driving wore away the insulation and caused a short. Thought something like that might have happened again, but I couldn't find any visual evidence of a problem. Zoning is very strict where I live, and I had to scrap the vehicle to avoid being fined for each day the vehicle remained on my property. I believe it would have been a simple electrical problem to fix, if it wasn't such a difficult electrical problem to identify. I would still like to know what it might have been, as this was the first time I wasn't able to eventually repair a vehicle. If you make any progress, please post the results here to satisfy my own curiousity and possibly help others with the same problem. Thanks and best of luck!

 

i watched a thread like this one time. The ground wire for the dash was the issue. I have no idea where that ground is. But i guess start looking.