Dimsdale
01-21-2005, 07:38
Hi guys!
Okay here is the situation: during our current cold spell (about -11 to +17F), I had a fuel starvation episode. It happened after driving about 55 miles in this cold (with a winterfront), while driving at about 65 mph.
Long story short, pulled over, it would barely idle, stalled twice, obviously fuel deprived. Let it sit and heat soak, suspecting fuel waxing. This seemed to work, along with the addition of an emergency dosage of PowerService fuel conditioner. Stalled once afterward, then made it home with normal power. Changed the filter (had about 15K on it, fairly dirty) and situation seems to be remedied. (anyone know how to check the fuel heater?)
The problem: now there is an off-idle shake reminiscent of a non firing cylinder. It idles normally and smoothly, but just off idle (800-1000 rpm in neutral or drive) it will seem "out of balance" then apparently smooth out. Seems to be rougher after the tranny locks up at about 55mph (about 1500 rpm). It starts normally and quickly. No smoke other than the occasional steam associated with this extreme weather. I use the block heater for 2 hours prior to leaving home. There does not seem to be a noticeable lack of power, either in city driving or highway driving. No stalling.
I am suspecting that it is one or more of the injectors that are not operating fully or at all. The imbalance always seemed to be present in this engine (see below), but is now more pronounced.
The questions: could it be the injectors (vs. the injection pump, or simply too much PowerService, or air in the system from the filter change?
The truck: 1999 GMC Suburban with F engine, which was changed at about 75K due to the infamous cracked block, the injection pump and turbo were also changed for associated reasons. Current mileage is 140,200. The injectors are presumably the originals, unless a long block comes with new injectors installed, so I undoubtedly got my money's worth. Tranny shifting normally, turbo fine. Amsoil air filter and remote oil bypass filter, filled with Rotella 5W-40 synthetic. Remote FSD (next to fender behind antilock brake unit under hood. All guages reading normally and no SES. Nothing leaking. No obvious residue or water (or waxy haze) in filter drainage when filter changed. Last time I looked, the harmonic balancer seemed to be fine, but I will try to check before the nor'easter (that's a !?*&load of snow to you non-New Englanders!) hits this Saturday afternoon.
I don't want to change anything I don't have to, especially in this weather (no garage or paved driveway!), and with an eye to the fact that I was "downsized" just before Christmas, so money will be an issue. If I can coast until spring, great, but I will not ignore it if it is more serious. If you can think of anything to check on Saturday morning, let me know. I can pull codes (Autotap on laptop) if necessary.
Thanks in advance!
Larry a.k.a. Dimsdale
member #34 before the big server crash!
Okay here is the situation: during our current cold spell (about -11 to +17F), I had a fuel starvation episode. It happened after driving about 55 miles in this cold (with a winterfront), while driving at about 65 mph.
Long story short, pulled over, it would barely idle, stalled twice, obviously fuel deprived. Let it sit and heat soak, suspecting fuel waxing. This seemed to work, along with the addition of an emergency dosage of PowerService fuel conditioner. Stalled once afterward, then made it home with normal power. Changed the filter (had about 15K on it, fairly dirty) and situation seems to be remedied. (anyone know how to check the fuel heater?)
The problem: now there is an off-idle shake reminiscent of a non firing cylinder. It idles normally and smoothly, but just off idle (800-1000 rpm in neutral or drive) it will seem "out of balance" then apparently smooth out. Seems to be rougher after the tranny locks up at about 55mph (about 1500 rpm). It starts normally and quickly. No smoke other than the occasional steam associated with this extreme weather. I use the block heater for 2 hours prior to leaving home. There does not seem to be a noticeable lack of power, either in city driving or highway driving. No stalling.
I am suspecting that it is one or more of the injectors that are not operating fully or at all. The imbalance always seemed to be present in this engine (see below), but is now more pronounced.
The questions: could it be the injectors (vs. the injection pump, or simply too much PowerService, or air in the system from the filter change?
The truck: 1999 GMC Suburban with F engine, which was changed at about 75K due to the infamous cracked block, the injection pump and turbo were also changed for associated reasons. Current mileage is 140,200. The injectors are presumably the originals, unless a long block comes with new injectors installed, so I undoubtedly got my money's worth. Tranny shifting normally, turbo fine. Amsoil air filter and remote oil bypass filter, filled with Rotella 5W-40 synthetic. Remote FSD (next to fender behind antilock brake unit under hood. All guages reading normally and no SES. Nothing leaking. No obvious residue or water (or waxy haze) in filter drainage when filter changed. Last time I looked, the harmonic balancer seemed to be fine, but I will try to check before the nor'easter (that's a !?*&load of snow to you non-New Englanders!) hits this Saturday afternoon.
I don't want to change anything I don't have to, especially in this weather (no garage or paved driveway!), and with an eye to the fact that I was "downsized" just before Christmas, so money will be an issue. If I can coast until spring, great, but I will not ignore it if it is more serious. If you can think of anything to check on Saturday morning, let me know. I can pull codes (Autotap on laptop) if necessary.
Thanks in advance!
Larry a.k.a. Dimsdale
member #34 before the big server crash!