• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

I have a 1995 6.5 with a cold start smoking & stumbling issue I can't figure out?

WayneB

WayneB

New Member
Messages
18
Reaction score
22
Location
Pittsburgh
I'm Crying Uncle... It's time to ask the brain trust!

I have a 1995 6.5 with a cold start smoking & stumbling issue I can't figure out?
Here is what has been done.

Checking for air in the fuel:
* I have went through the fuel system front to back, supply and return. Using the clear hose to look for air. I did find a couple air leaks and fixed them.

* I have noticed a couple bee bee sized air bubble in the line after letting it set over night (cold is 40deg. or so) I also have about 1 second's worth of small bubbles quickly passing then it starts, it quickly clears and runs. Where is that second's worth of bubbles/foam coming from on start up? It comes and passes pretty quick so it's not far down the fuel system?


Checking the IP timing:
I adjusted the IP average to 3.0 ~ 4.0 = 3.5 avg. and the TDOC to .88 It sure don't take much to move things. I was working to the right or left of the witness mark chiseled into the metal.

Here is an odd observation. When I plug in the block heater overnight there are no start up problems. The truck starts right up with next to no smoke or coughing... with that small amount bubbles passing.

What's left?
It must be something metal that closes up when warm?
If it was an injector leaking fuel it would do it warm or cold. Yes?
I'm not loosing any coolant, and again it would do it warm or cold.
Would a loose IP line not under pressure leak air and not fuel? I don't see any fuel leaking in the valley.
Truck starts and runs fine when warm.

I'm at a loss....? Anyone have any suggestions?

Other work done:
New glow plugs, harness and controller from Quadstar.
New Bosch injectors from Accurate diesel.
New main wiring harness Quadstar.
New fuel manager from Quadstar...
New rebuilt IP from Quadstar. Installed and set it up by John himself. Yup, John lives about 12 miles from me. The white smoke started as things got progressively colder around here. The colder it gets the worse the smoke and stumbling gets.
 
ak diesel driver said:
unplug the temp sensor in the coolant crossover and report back what happens when you start it cold
Click to expand...
Pulled the sensor, truck started right up NO SMOKE, NO STUMBLING, NADA!!! I have been trying to chase this Gremlin out for an embarrassingly long time!!! Never once thought to look that direction or disconnect that sensor... I changed them all last summer... Good to go now!!! Right??? A bad sensor? New broke stuff happens to me a good bit! Bought a pair of jeans with the pocket sewed shut and one leg 2" longer than the other one, once! Twice!

Ok where to from here? Put the old sensor back in or do things point back to timing? Thanks for the help!
 
Do you have a scanner to read data? The coolant temp sensor could be reading incorrectly and giving your PCM the wrong temp reading. You can check that with a scan tool. If you don't have one you could ohm it and compare it to the temp/resistance chart for that sensor. Let it sit overnight so it at ambient temp.

When you unplug it the PCM will see negative 40*. But it knows that not a true number so the PCM will default to a preset strategy.
 
Well it is not the coolant sensors, both of the ones I have here check out to the GM chart. That IP can't have 3000 miles on it? Well there's another pocket sewed shut! I was looking at the function of the DB4 (NAVEDTRA-14050A-Construction-Mechanic-Advanced-Part-3.pdf) to see how that advance works... If I'm reading right that advance piston is in constant play from an Idle to full throttle? Better read some more.... I see the optical sensor has a fuel temprature sensor too? Trying to track down this problem earlyer I did see where the DB2 has a simple looking external advance hanging off the side of the pump for cold starts.

Thanks to everone for the help! But if it's IP I'm going to end up on Quadstar John's door step for a "Howdy" and see how things go from there. John's always been pretty easy to work with.
 
So...

“* I have noticed a couple bee bee sized air bubble in the line after letting it set over night (cold is 40deg. or so) I also have about 1 second's worth of small bubbles quickly passing then it starts, it quickly clears and runs. Where is that second's worth of bubbles/foam coming from on start up? It comes and passes pretty quick so it's not far down the fuel system?”

Standyne and GM taught the clear return line was step 1. Now that you see you are getting some and you cant definitely find he source- you need to put on 5/16 (3/8 if FTB done) inplace of the FFM to IP line. If there is NO bubbles in the feed line and there is bubbles in the return line, the IP is the source. If there is bubbles in the feed line, you have to keep chasing it back. I have dreamed for years of clear viton fuel line rated sae30r9 to run from tank to ip and back. Until then, this is a pain in the neck.

All that said, you mentioned:
“Here is an odd observation. When I plug in the block heater overnight there are no start up problems. The truck starts right up with next to no smoke or coughing... with that small amount bubbles passing.”

If adding heat solves the problem- that tells me your glowplugs are not adding the needed heat. Yes a small amount of air in the fuel will make it worse, but if the air is not enough to create any noticeable problem when you plug in the block heater- then it isn’t much air.

So in my opinion - you have a glowplug system problem.
remove all the glowplugs. Hook up a heavy duty copper fine strand 8awg ground wire and wrap it around every glowplug threaded area and back to the battery negative. Have someone turn on the the key as if about to start and monitor the plugs to see that they are heating properly.

You might not be getting the cold advance you are supposed to also as another contributor with the small air intrusion. But again, if the block heater “fixes it” then you are lacking heat.
 
Forgot to mention, if anyone ever finds no air bubbles before the ip, and has bubbles afterwards indicating the IP-
With the engine cool, look for signs of wet all around the IP and note what you see. Take pics- often others can see what one person misses.

Then clean outside of ip with brake cleaner. Once dry, use Vaseline (petroleum jelly) and place a small amount over the seamed areas, shaft seals, etc. Then have someone start it while you watch for the bubbles out return line again. The Vaseline will form a seal and stop the air coming in. If any does get sucked in it wont destroy the ip, it dissolves into the fuel just lowering flash point a hair because it is just thicker petroleum.
(Somehow people still think putting it on their lips and body is smart. At some point they’ll prove it is unhealthy- I just can’t believe they haven’t yet- its flippen petroleum for cryin out loud! Medical rant over).
ANYWAYS...
You cant reach the front of the ip the weep hole is there to reveal bad front seal- but often what you can reach reveals the leak because leaks are most common where air gets to the outside, most often in db pumps is the throttle seal.
 
Will L. said:
So...

“* I have noticed a couple bee bee sized air bubble in the line after letting it set over night (cold is 40deg. or so) I also have about 1 second's worth of small bubbles quickly passing then it starts, it quickly clears and runs. Where is that second's worth of bubbles/foam coming from on start up? It comes and passes pretty quick so it's not far down the fuel system?”

Standyne and GM taught the clear return line was step 1. Now that you see you are getting some and you cant definitely find he source- you need to put on 5/16 (3/8 if FTB done) inplace of the FFM to IP line. If there is NO bubbles in the feed line and there is bubbles in the return line, the IP is the source. If there is bubbles in the feed line, you have to keep chasing it back. I have dreamed for years of clear viton fuel line rated sae30r9 to run from tank to ip and back. Until then, this is a pain in the neck. In trying to resolve this problem I installed an airdog system with all new 3/8" end to end. I thought perhaps the old LP (Old, New) may have been cavitating the fuel?

All that said, you mentioned:
“Here is an odd observation. When I plug in the block heater overnight there are no start up problems. The truck starts right up with next to no smoke or coughing... with that small amount bubbles passing.”

If adding heat solves the problem- that tells me your glowplugs are not adding the needed heat. Yes a small amount of air in the fuel will make it worse, but if the air is not enough to create any noticeable problem when you plug in the block heater- then it isn’t much air. Block heater or pulling the coolant temp sensor did the trick too. I pulled the sensor and it fired right off with the normal small puff.

So in my opinion - you have a glowplug system problem. This is all new too... New relay, New harness from John at QS. and new glow plugs. Also just got done going over every ground in the system, including resoldering the ground splices in the main harness. They had a little white corrosion around them..
remove all the glowplugs. Hook up a heavy duty copper fine strand 8awg ground wire and wrap it around every glowplug threaded area and back to the battery negative. Have someone turn on the the key as if about to start and monitor the plugs to see that they are heating properly.

You might not be getting the cold advance you are supposed to also as another contributor with the small air intrusion. But again, if the block heater “fixes it” then you are lacking heat. Looks like I'll go through the glowplugs again... Could be a bad one in the bunch..? But the truck fires off just fine with the coolant temp sensor disconnected. I'm thinking perhaps calling in a Priest for an Exorcism! Garlic on the mirrors.. LOL
Click to expand...
 
Will L. said:
Forgot to mention, if anyone ever finds no air bubbles before the ip, and has bubbles afterwards indicating the IP-
With the engine cool, look for signs of wet all around the IP and note what you see. Looks like the manifold is coming off too, again. Been holding this one off for last. Take pics- often others can see what one person misses. Yuppers!

Then clean outside of ip with brake cleaner. No need to clean, its brand new only 3000 miles since it was put in....Once dry, use Vaseline (petroleum jelly) and place a small amount over the seamed areas, shaft seals, etc. Then have someone start it while you watch for the bubbles out return line again. The Vaseline will form a seal and stop the air coming in. If any does get sucked in it wont destroy the ip, it dissolves into the fuel just lowering flash point a hair because it is just thicker petroleum. I used Vaseline around the o-ring for the fuel shut off solenoid in my earlyer process of elimination looking for air. Did find damage on the inlet o-ring. One of the air leaks-replaced.
(Somehow people still think putting it on their lips and body is smart. I don't get the lay on the beach thing eather. Smear oil all over yourself and roll in the sand...Ok! At some point they’ll prove it is unhealthy- I just can’t believe they haven’t yet- its flippen petroleum for cryin out loud! Medical rant over).
ANYWAYS...
You cant reach the front of the ip the weep hole is there to reveal bad front seal- but often what you can reach reveals the leak because leaks are most common where air gets to the outside, most often in db pumps is the throttle seal. That pump is about the only thing left? I just want to make sure I have eliminated all the other possibilities before heading there...

Can't thank everyone enough for their time!
Click to expand...
 
“Block heater or pulling the coolant temp sensor did the trick too. I pulled the sensor and it fired right off with the normal small puff.”

I missed the point that pulling the temp sensor allowed it to start properly. If that is the case- then the glows ARE working ok.
I am confused- there is something I am missing here and can’t see what I should. EVERYONE HELP please, I am not seeing the culprit but it is in this circuit,Focus on this - the problem is here. I want to say bad sensor, but it tested ok. Bad connection maybe? Faulty wiring after the sensor? Unplugging the 2 wire sensor basically sends the signal to advance time and maximum glow time right(?) so could it be longer glow?

Are you positive the advance is engaging when the 2 wire sensor is connected and it isn’t starting properly?


After you replaced the lift pump and did 3/8” line all the way to the ip (great upgrade btw), are you still getting the bubbles?
 
You must log in or register to reply here.
Back
Top