I have a 2000 Chevy Trailblazer with 156k miles.
Within the last month when at a stoplight or stop sign or even when I hit the brake backing into the driveway, the car’s engine will shutoff. The only way to fix is to put the car in park and then turn the engine back on turning the key in the ignition. The problem does not happen all the time, which is making it frustrating and harder to diagnose.
I’ve been two different mechanics, both who have had the car for over a week. Neither one had the issue happen to them while driving it. They both checked for error codes, none appeared on the engine, gas pump, nothing. One mech did a smoke test and found some leaks which he fixed, but the still occurs.
The car run great otherwise. No check engine lights or other apparent issues.
Any idea what this could be? It’s my wife’s primary car so I’m concerned about her driving it since we don’t know what’s causing this.
Anyone inspected wiring or the battery connections? It sounds more like an electrical problem, like if power was lost immediately rather than a fuel problem or an engine problem. A vibration can cause a poor connection to completely open or cause an uninsulated wire to short out. Very little could cause the poor connection to close again and you’d have difficulty finding it.
wiring has been checked with the first mechanic but not the second
but why does the problem only happen when the brakes applied. I would think as driving on rough roads and potholes that would jar something loose.
Blazers are known for their fuel pumps going out. You might hear the fuel pump engage but that doesn’t mean it is putting out enough fuel pressure to keep the engine running. Your best bet is to have it towed to a local shop and let them run a pressure test to check and see if your getting enough fuel pressure or if your a big do it yourself type you can rent a pressure tester from auto zone or your local auto parts store. If you don’t want to do that you can get a fuel pump for around 3 to 4 hundred dollars and replace it and see if that cures the problem.
I suspect the fuel pump also. I had it changed 6-7 years ago when the fuel gauge started to say full when it was almost emply!
When I did change it it was $800-$900 so I was hoping for something definitive before I replaced it. I would be upset with myself spending almost 1000 on 18 year old car and the problem still recurring. I was hoping for the errors code or the mechanics to see something concrete before I made that change.
and we did check fuel pressure. it was fine when tested but doesn’t mean that that is not the issue since the problem does not happen all the time. and never happens when the gas pedal is pressed.
Is your oil pressure light coming on when your key is in the position to turn on all the instruments and warning lights? What I’m getting at is this: the oil pressure sending unit might be reading too low, and that causes the computer to turn off the engine. The problem would be most apparent at low RPMs, when oil pressure is at its lowest. It might also be the engine does have very low oil pressure, but that’s less likely if it has oil and has been well maintained.
Having owned three Trailblazers, I can tell you a common problem on early versions is carbon buildup in the throttle body. Has the throttle body ever been cleaned? It’s quite easy to inspect by removing the intake air hose and opening the throttle plate…
Hi thanks shanonia
Oil pressure light has never come. I get oil changes regularly and has never been issue before.
dont know if the throttle body has been cleaned. that’s something I can ask the mechanic to see if he did.
thanks for the suggestion.
do you remember what the fuel pressure was? Off the top of my head, it needs to be around 60psi to run well. It will run with less, but that can show signs of a dying pump.
Hi eddo - I remember them saying it was 55.
which engine is in this 2000 Trailblazer?
55 seems a bit low, but not where it should cause you issues. Has the fuel filter been replaced lately?
7ish years is about what I have seen out of GM fuel pumps in my experience, thus why I’m asking about that.
eddo def been more than 5-6 years since gas pump change, easily.
When I changed it before it was because the tank was near empty and the gauge would say full!
I know the gas gauge and pump are all one unit and it cost me $900 last time. Would hate to spend that money and have it NOT be the issue…
The problem might be with a dirty/faulty Idle Air Control valve.
The IAC valve is what allows the engine to idle under all conditions whenever the accelerator is released.
read somewhere else that could be the issue too. Thanks Tester.
If it only happens when you hit the brakes I would be looking at vacuum lines and brake booster
Assuming this problem occurs when the engine is fully warmed up, here’s some ideas
The engine idling rpm may be too low, below spec.
Too lean at idle, check for vacuum leaks
Engine is behind schedule on needed maintenance, spark plugs, engine air filter, verification of ignition timing, and the like
Transmission or torque converter problem (if automatic)
Engine compression is too low