I have a 2003 GMC Yukon. Upon a cold start it spits and sputters like crazy and tries to die out. Sometimes, if it doesn’t start it will turn over like it is trying but will not unless you press the gas pedal to the floor and try starting it. Then it smells really funny. We replaced the fuel pump, $300 :(, which only helped for about a week. And also the vacuum canister that is beside the gas tank. My husband also found a short going to the purge vent valve that he also fixed. After it gets going it seems fine, sort of but, when you hit a rough place in the road or a pot hole it acts like its going to die. The brake lights come on and stay on til you actually turn the car off and back on, and the doors unlock. Also, it has died completely a couple of times while driving and it makes a humming sound when this happens. I tried wiggling the keys while it was running and it did not die. We changed the bolts in the battery and bungy strapped it down, no burn marks under hiod.We are going crazy trying to figure this out as we have spent several hundred dollars and it is not fixing the problem. At one point in time, a previous owner had a system installed, all that is left are the wires throughout the car. Another thing is it has a dial for the heater/ac, when you turn it up the temp goes up and down not just up, same as if you turn temp down it goes up and down. It will eventually get to the temp you want it set at but it takes an act of congress to do so. We have turned the car on wiggled every harness accessible, checked the fuses and wiggled on them. Took the dash out checked for bare wires. Wiggled bcm and wires from it, nothing happens. At a complete loss on what to do. Please help!!!
Check engine light is on but does not read any codes when checked.
Have you considered getting a new car?
Not trying to be snarky, this just sounds like it’s not worth the effort to solve at this point.
IANAM, but I believe the technical term for this condition is “broken.” See a real mechanic to be sure.
These types of problems are almost always either:
- A chafed wire that is touching ground when the car hits a bump or
- A loose ground wire.
Where is best place to start looking? There are thousands of wires wrapped up in those looms. That would take a month.
First thing I would check for is corrosion at the wire harness plugs, possible the one at your firewall. You have to examine them pretty closely as it is not always very obvious.
With the car running, push, prod, pull, and poke at every wire you can find, and see if you can replicate the problem.
I’m stumbling over the fact that the “check engine” light is on but there are no codes. if that’s truly the case then I might think the PCM has failed.
Some of the problem reminds me of my Dad’s old shitty Jeep Wrangler, the person who had installed the cd player I think had wired something wrong because the aftermarket cd players don’t have some 12 volt adapter wire or something. You see the cd player has a memory so its supposed to suck up a certain amount of juice even when the car turns off to maintain your presets and such. Do a little googling and you will find this is a big issue with Chevy’s, where the car is off and the radio keeps playing or it makes this whining noise.
Something odd like this happened with my Dad’s jeep and the cd player and this other accessory would just suck all the electricity out of the already old battery and he didn’t drive the car that much so it would always be dead when he tried to crank that thing up.
Until you figure out the wiring thing you might have to buy a new battery or drive it around for a while and get the battery all charged up and then physically disconnect the battery every time you turn the car off, that’s what I had to do when I borrowed my Dad’s Jeep for a while.
But it sounds like this thing has a lot of issues:
When you try to start the car does it turn over, if its not turning over then you don’t have enough juice, is it just making crazy clicking noises? Then it might be the starter itself, a refurbished one isn’t super expensive.