My 2001 Chev Silverado 1500, 5.3L, 260,000 K miles may finally be near the end - but I wanted to see if anyone here has seen something like the following first:
It has been running great until this week. I live in Portland - weather was down to about 10 deg F a few nights and when it warmed up again the trouble started. After starting cold and driving for about 15 minutes it starts stalling out. Sometimes it will fire right up again and I’ll hardly notice except for a momentary drop to 0 on the tach. Other times I’ll have to pull off to the side to the road and restart it. However, 2 times now it would not restart and stay running. It would either fire up but then die within 10 seconds, or it would just crank. Both those times it did restart successfully after 40 minutes had passed total and it drove fine afterwards until I got where I finished my commute (about another 5-10 minutes of driving).
I took it to a mechanic who could see it stall but was not able to duplicate the 40 minutes out of commission thing. His fuel pressure gauge indicated that the pressure was fine during the stall outs. The mechanic ran the computer diagnostics but didn’t see anything unusual. He wasn’t really sure what the problem was. He recommended replacing the fuel pump and fuel filter anyways - but couldn’t say if that would make any difference.
Has anyone seen this kind of problem? Should I start throwing money into new parts or move on and start looking for a new vehicle?
If the fuel pressure is OK during the stall, it sounds more like an intermittent electrical problem. A bad crank angle sensor can cause random stalling, as can other things like a bad connection somewhere.
The crank angle sensor can be sensitive to heat, so that could explain the 40 minutes needed for the engine to cool before it would restart.
If it were me I’d say it was worth putting a few hundred more bucks into it, starting with the crank angle sensor.
Thank you very much for the advice and quick replies. I have booked another visit to a mechanic to have them check on the crank sensor. Updates when I have them.
Tell the mechanic “I am not paying you for diagnosis. I am paying you to replace the crankshaft position sensor. Please perform the crankshaft sensor variation learn after replacing the sensor. I accept full responsibility if this does not fix the problem.”
By not paying for diagnosis, you will save a few bucks. Diagnosis with an intermittent problem is hit and miss. If there are no stored codes, and the car is fine right now, tests may not reveal much.
Thank you for the follow up advice. The mechanic still wanted to do his own diagnosis - but I negotiated for them to do it for free. They called back and recommended changing the crank sensor and the fuel pump. Based on the confidence in your diagnosis on this thread I had them just do the crank sensor ($420 for install and relearn). Not blindly following their recommendations like I often would on something like this has saved me a lot of money - around $850 for the fuel pump install.
Got my truck back last night and it appears to run as well as ever.
I also asked why exactly they were recommending a new fuel pump and am supposed to get a call back but haven’t yet. The mechanics report did not give any specifics - but I am guessing that the failing crank sensor caused erratic usage of the pump leading the mechanic to think it was failing.
Hopefully that does the trick. Let us know in a week or so if it’s definitely solved. Meanwhile, as long as the truck is running fine, you don’t need a fuel pump.
When you initially turn on the ignition, the fuel pump gets energized. However, it won’t continue to get power if there’s no crank signal within a few seconds
Hopefully the new crank sensor takes care of the problem
Your explanation on the energizing of the fuel pump and how it loses power after a few seconds would totally explain why during my 40 minute stall outs I could start my vehicle for a very short time.
Two days of driving now - and everything is still working good. I never heard back from the mechanic/shop - but I am pretty certain you guys helped me avoid an unnecessary fuel pump replacement.
