Chief915
915A Maint Tech
Hey all, been awhile since I posted or even been on the forums. I've been busy moving from GA to KY, but I am finally getting settled in a little.
I am having a problem with the 94 in my signature. It isn't starting so well lately. It is colder here in KY, about 40 or so the last couple mornings, but it was beginning to do this same thing before I left southern GA where it was 65-70 in the mornings.
The problem:
First start of the day, the glow's will come on and stay on for about 10-15 seconds then go out. The truck cranks over fine, nice and fast, after about 4 or 5 seconds it will begin to fire on 5 or 6 cyls, enough to make me let go of the key, but it doesn't start. I have a manual glow button.... I will normally hold the glows on another 6-8 seconds at this point. On the second try, and another 4 or 5 seconds of cranking, it will finally start up, puff lots of black smoke mixed with a little white, and run at about 400-500 RPM for maybe 5 - 10 seconds, then it rattle's loud (diesel clatter) for half a second and starts running real nice and smooth at normal cold idle RPM (800-900 ?). If I tap the throttle while it's running slow and smoking, it will rattle loud and start running normally as soon as I tap the pedal. Once that is all over, it runs great....no missing, smoking, stalling, rough running, low power, etc. After it's been running, it starts easier, but still doesn't seem like its "right" to me. Wait light will still come on for anywhere between 1 second and 3 or 4 seconds, but it still cranks over for 4 or 5 seconds before it starts, even after the engine is up to temps. This has been going on for a couple months at least. In contrast the Hummers at work will start with basically a bump of the starter once they are warm.
What we're working with:
The glow plugs are about 5 month old AC 60G's (I put them in myself), batteries are 10 month old optima red tops, 2/0 battery cables, all connections are clean as of one week ago. This includes battery connections, GP relay connections, all grounds (battery grounds, PCM grounds at the back of the intake, etc) The GP relay clicks normally while the GP's cycle on and off. I have about 10.x volts showing on my multimeter at the relay and at the couple GP's I have checked while the glow plugs are "on". Resistance on all the GP's is about the same, don't recall the reading, but it wasn't much and none were open or 0 ohms.
Timing has been set with GMTD scan tech, TDCO has been set from -1.2 to -1.94 without any change to the problem. The fuel filter has been changed with no effect on the problem, PMD was swapped with a brand new D-Tech PMD with no change to the problem. I jumped the fuel pump relay and let the fuel pump run for 30-45 seconds before I tried to start it to rule out possible air in the system or losing prime, no change at all to the way it acts. The truck started this same way with both the factory PROM and the Heath P-series PROM. No codes, never have a check engine light. All rubber fuel lines have been replaced, no change to the problem. Injectors have about 10,000 miles on them.
It doesn't act like air in the fuel to me because it runs smooth once it starts and starts exactly the same whether it only sat overnight or for a week straight. It seems like the longer it sat, it would be even harder to start because of more air in the line. I am leaning toward the glow system, but everything seems to test good there.
I will try to remember to make a video of starting it in the morning, easier to watch than to describe.
What are your thoughts?
I am having a problem with the 94 in my signature. It isn't starting so well lately. It is colder here in KY, about 40 or so the last couple mornings, but it was beginning to do this same thing before I left southern GA where it was 65-70 in the mornings.
The problem:
First start of the day, the glow's will come on and stay on for about 10-15 seconds then go out. The truck cranks over fine, nice and fast, after about 4 or 5 seconds it will begin to fire on 5 or 6 cyls, enough to make me let go of the key, but it doesn't start. I have a manual glow button.... I will normally hold the glows on another 6-8 seconds at this point. On the second try, and another 4 or 5 seconds of cranking, it will finally start up, puff lots of black smoke mixed with a little white, and run at about 400-500 RPM for maybe 5 - 10 seconds, then it rattle's loud (diesel clatter) for half a second and starts running real nice and smooth at normal cold idle RPM (800-900 ?). If I tap the throttle while it's running slow and smoking, it will rattle loud and start running normally as soon as I tap the pedal. Once that is all over, it runs great....no missing, smoking, stalling, rough running, low power, etc. After it's been running, it starts easier, but still doesn't seem like its "right" to me. Wait light will still come on for anywhere between 1 second and 3 or 4 seconds, but it still cranks over for 4 or 5 seconds before it starts, even after the engine is up to temps. This has been going on for a couple months at least. In contrast the Hummers at work will start with basically a bump of the starter once they are warm.
What we're working with:
The glow plugs are about 5 month old AC 60G's (I put them in myself), batteries are 10 month old optima red tops, 2/0 battery cables, all connections are clean as of one week ago. This includes battery connections, GP relay connections, all grounds (battery grounds, PCM grounds at the back of the intake, etc) The GP relay clicks normally while the GP's cycle on and off. I have about 10.x volts showing on my multimeter at the relay and at the couple GP's I have checked while the glow plugs are "on". Resistance on all the GP's is about the same, don't recall the reading, but it wasn't much and none were open or 0 ohms.
Timing has been set with GMTD scan tech, TDCO has been set from -1.2 to -1.94 without any change to the problem. The fuel filter has been changed with no effect on the problem, PMD was swapped with a brand new D-Tech PMD with no change to the problem. I jumped the fuel pump relay and let the fuel pump run for 30-45 seconds before I tried to start it to rule out possible air in the system or losing prime, no change at all to the way it acts. The truck started this same way with both the factory PROM and the Heath P-series PROM. No codes, never have a check engine light. All rubber fuel lines have been replaced, no change to the problem. Injectors have about 10,000 miles on them.
It doesn't act like air in the fuel to me because it runs smooth once it starts and starts exactly the same whether it only sat overnight or for a week straight. It seems like the longer it sat, it would be even harder to start because of more air in the line. I am leaning toward the glow system, but everything seems to test good there.
I will try to remember to make a video of starting it in the morning, easier to watch than to describe.
What are your thoughts?
