Question: terrable white smoke at start up on 6.5 turbo

[towguy55]

OK guys i could really use some advice here,I have a beautiful 95 3500 HD GMC with 95000 miles that really bellows the white smoke after it sits overnight.Ive replaced the glowplugs with the new GM glowplugs and has a new controller on it.The only thing that helps the startup is disconnecting to coolant sensor at startup but seems to read good on a scan tool.Ive been reading TSB's on this engine and GM has had issues with the prom and reccomends an update BUT none are available through GM anymore..Do you guys think this might be an issue here and if so what do you reccomend ...look forward to getting some input here...thanks so much....

[FloridaHorseman]

Originally Posted by towguy55

OK guys i could really use some advice here,I have a beautiful 95 3500 HD GMC with 95000 miles that really bellows the white smoke after it sits overnight.Ive replaced the glowplugs with the new GM glowplugs and has a new controller on it.The only thing that helps the startup is disconnecting to coolant sensor at startup but seems to read good on a scan tool.Ive been reading TSB's on this engine and GM has had issues with the prom and reccomends an update BUT none are available through GM anymore..Do you guys think this might be an issue here and if so what do you reccomend ...look forward to getting some input here...thanks so much....

Disconnecting the ECT and getting less smoke on a cold start indicates the EPROM is doing its job by extending the GP glow and engaging the stepper motor. As cheap as they are, I'd replace the ECT sensor no matter what the scanner says. If you're convinced it's an EPROM problem you can get a performance flashed upgrade from one of the sponsor vendors here. ~FH

[towguy55]

Thanks for the reply..well the fact is the ect sensor was one of the 1st things i replaced..lol..and to be honest i'm really not convinced its in the eprom,just kinda threw that out there..its also had the IP rebuilt a few yrs back..what are your thoughts to extending glow plug time ?..

[racer55]

A manual glow override would help likely:
How To - Glow Plug Override

Or an aftermarket tune with a longer glow duration programmed in.

BTW:AC Delco ONLY for sensors and electronic parts on these trucks-the aftermarket parts are not up to the job.

[JMJNet]

For GPs, Bosch comes out ahead of GM's ACDelco.

Anything that said Sender, Sensor, Thermostat, all need to be GM aka ACDelco as racer55 said.
Example OPS, CTS, ECT, Thermostat.

[crankme69]

Did you check the wire to each glow plug for power when you installed the new ones?

[towguy55]

yep i checked for current at each g/p connector and all checked OK and the temp sensor was ac delco..also new stat...

[Kennedy]

Originally Posted by towguy55

OK guys i could really use some advice here,I have a beautiful 95 3500 HD GMC with 95000 miles that really bellows the white smoke after it sits overnight.Ive replaced the glowplugs with the new GM glowplugs and has a new controller on it.The only thing that helps the startup is disconnecting to coolant sensor at startup but seems to read good on a scan tool.Ive been reading TSB's on this engine and GM has had issues with the prom and reccomends an update BUT none are available through GM anymore..Do you guys think this might be an issue here and if so what do you reccomend ...look forward to getting some input here...thanks so much....

Disconnecting the ECT sensor at startup extends the glow time making more heat. Start with a fresh set of Quick Heat plugs. The AC 60g's are too slow. If that does not work then extended glow time via chip tuning. I've had extended glow in my chips for many years now and the 18:1 engines start clean and run smooth without additional interaction. If these two don't take care of it and your compression checks out uniform, then it's down to the pump. I've seen the DS pumps give really crappy cold starts before for some strange reason. New pump cured the issue. Let's hope the improved glow heat takes care of yours.

[crankme69]

I was having issues with mine starting cold & it turned out to be lift pump & lines needed replacing. I determined that a few different ways.

1st is place the shifter into gear & then hold the starter in the start position on 1995 years that should run the lift pump. Running the LP should help clear out any air that may have found it's way in while the vehicle sets.

2nd install a clear piece of tubing on the IP return line & check for air bubbles in the am before starting the truck. A very small bubble is normal, large & continuous bubbles during & after startup are not.

3rd hook up temp pressure gauge & verify the fuel supply from the LP at idle & WOT. Just cause the LP is running doesn’t mean it’s doing anything.

My OEM LP & the associated fuel lines were all toast.

HTH's

[FloridaHorseman]

Originally Posted by towguy55

Thanks for the reply..well the fact is the ect sensor was one of the 1st things i replaced...

Well, if the problem always clears up with the ECT sensor disconnected I fail to reasonably see how it could be anything else. It's possible to get a bad "new one", especially with aftermarket stuff. It could also be the connector itself shorting across the pins but only when it's in place.

Originally Posted by towguy55

..and to be honest i'm really not convinced its in the eprom,just kinda threw that out there..its also had the IP rebuilt a few yrs back..what are your thoughts to extending glow plug time ?..

Extending the heat on GPs that aren't rated for it may not be a good idea but I'll defer to the more knowledgeable folks on that. ~FH