Hard Start / Stall

Shooter_va · September 14, 2009

2001 8.1L: Over the past few weeks the truck will not start - cranks fine, but no ignition (takes 4 to 5 tries before firing). This past weekend the truck stalled twice on me while driving (completely cut off), had to pull over and it took a few times cranking to start again.

No CEL / Code. Haven't had a chance yet to hook up a fuel pressure gauge, do you think it could be the fuel pump?

txab · September 14, 2009

2001 8.1L: Over the past few weeks the truck will not start - cranks fine, but no ignition (takes 4 to 5 tries before firing). This past weekend the truck stalled twice on me while driving (completely cut off), had to pull over and it took a few times cranking to start again.
No CEL / Code. Haven't had a chance yet to hook up a fuel pressure gauge, do you think it could be the fuel pump?

Strong possibility. Changed your fuel filter lately? Check your pump pressures.

Shooter_va · September 14, 2009

2001 8.1L: Over the past few weeks the truck will not start - cranks fine, but no ignition (takes 4 to 5 tries before firing). This past weekend the truck stalled twice on me while driving (completely cut off), had to pull over and it took a few times cranking to start again.
No CEL / Code. Haven't had a chance yet to hook up a fuel pressure gauge, do you think it could be the fuel pump?

Strong possibility. Changed your fuel filter lately? Check your pump pressures.

I'll check the pressure tomorrow and I am due for a fuel filter chance (32k since last change).

xwire · September 14, 2009

I would suspect cam or crank sensor (have had to replace both over the years)

Shooter_va · September 14, 2009

I would suspect cam or crank sensor (have had to replace both over the years)

Did the crank shaft sensor a couple of years ago, back then it did through a code.

JoJoJim · September 15, 2009

I would suspect cam or crank sensor (have had to replace both over the years)

Did the crank shaft sensor a couple of years ago, back then it did through a code.

Mine was similar and it was a crank sensor. JoJoJim

xwire · September 15, 2009

just got done doing a crank sensor in mine (old one was slightly longer then the new one and showed marks as it had been ground by the crank tuning wheel) showed the same symptoms as you describe

would be driving along and truck would just die while driving sometimes it would start right back up, most times it would take a bit. may have done it 5 times in one day or not do it for weeks at a time. was driving me crazy (almost to the point I was getting a new truck) as I would drive it with a scan tool reading on it and never have a problem out of it... finally per a recommendation from a GM tech friend of mine pulled the crank sensor (which was a PITA to get too) to inspect it. seen the grind marks, replaced it and knock on wood have not had another problem out of it

Shooter_va · September 15, 2009

just got done doing a crank sensor in mine (old one was slightly longer then the new one and showed marks as it had been ground by the crank tuning wheel) showed the same symptoms as you describe

would be driving along and truck would just die while driving sometimes it would start right back up, most times it would take a bit. may have done it 5 times in one day or not do it for weeks at a time. was driving me crazy (almost to the point I was getting a new truck) as I would drive it with a scan tool reading on it and never have a problem out of it... finally per a recommendation from a GM tech friend of mine pulled the crank sensor (which was a PITA to get too) to inspect it. seen the grind marks, replaced it and knock on wood have not had another problem out of it

It didn't through a code, though?

Shooter_va · September 15, 2009

Do you have to do the System Variation Learn Procedure (with scan tool) after replacing the crank sensor?

xwire · September 16, 2009

nope no code ever, that is what was driving me crazy

and no did not have to do anything but replace the sensor

Shooter_va · September 21, 2009

Got that thing changed.....what a PITA to get the old one out. Ratchet wrench is a must-have for this job, so is some penetrating oil (I used Kroil). My heart sunk though after the old sensor broke and a piece of the old sensor fell on my chest with about 2" still stuck in the engine......squirted on some more lubricant and got it out:

Replacement sensor only had one O-Ring and installed much easier.

xwire · September 21, 2009

Got that thing changed.....what a PITA to get the old one out. Ratchet wrench is a must-have for this job, so is some penetrating oil (I used Kroil). My heart sunk though after the old sensor broke and a piece of the old sensor fell on my chest with about 2" still stuck in the engine......squirted on some more lubricant and got it out:

Replacement sensor only had one O-Ring and installed much easier.

wow that looks worse then mine sis, let us know if this took care of you concern

Shooter_va · September 21, 2009

Truck started right up. I went for a test drive (about 30miles) and the truck drove fine, it actually appears that there is a better throttle response and power now.

tjg79 · September 22, 2009

Do you have to do the System Variation Learn Procedure (with scan tool) after replacing the crank sensor?

You should do the procedure. The GM service manual indicates it's required to bring the change back into spec.

xwire · September 22, 2009

Truck started right up. I went for a test drive (about 30miles) and the truck drove fine, it actually appears that there is a better throttle response and power now.

I felt the same way, that and a smoother idle as well, it's a good feeling not having to worry about your truck dying on your randomly isn't it