Glow Plug Issue

[Noladdermike]

Sorry to jump in on Dev11on's thread, but I have the same problem. I also have a 2004.5 Chevy LLY with 100,000 miles on it that I have owned for about a month. It has run perfectly until today when I tried to start it at 21 Deg F without plugging it in. The glow plug light ran a little longer than usual, but still only for a few seconds, then I had to crank it for a very long time before it started and it ran rough for awhile after that.

I am not getting a check engine light and I used a reader but it did not register any DTCs at all.

The previous owner ran a Tidy Tank that he did not keep full, this may have caused some condensation issues. I changed the fuel filter when I bought the truck.

Should I be looking at the glow plugs, the fuel filter, both, or something else.

Thanks for any suggestions you can give me.

[MTL_Dmax]

Originally Posted by Noladdermike

Sorry to jump in on Dev11on's thread, but I have the same problem. I also have a 2004.5 Chevy LLY with 100,000 miles on it that I have owned for about a month. It has run perfectly until today when I tried to start it at 21 Deg F without plugging it in. The glow plug light ran a little longer than usual, but still only for a few seconds, then I had to crank it for a very long time before it started and it ran rough for awhile after that.

I am not getting a check engine light and I used a reader but it did not register any DTCs at all.

The previous owner ran a Tidy Tank that he did not keep full, this may have caused some condensation issues. I changed the fuel filter when I bought the truck.

Should I be looking at the glow plugs, the fuel filter, both, or something else.

Thanks for any suggestions you can give me.

Yours sounds more like either fuel delivery or perhaps battery voltage issues.

1) Check battery voltage (should be 14+ volts with engine running)
2) How many miles on that current filter? Have you opened the valve and checked for water?
3) Check your actual vs demand fuel rail pressure (Edge Insight CS or CTS does this well)
4) Is the primer on the filter head hard? You may want to use some clear vinyl tubing going to the CP3 to look for air bubbles in fuel.

[K9Duramax]

Any results from above suggestions?

[Noladdermike]

Hi MTL_Dmax

I am still working on this.

I isolated the batteries and tested them individually with a volt meter and a smart charger that gives a percentage of charge, both were well over 12 volts and 100%. I am getting 14.7 volts with the engine running.

The pump on the primer was soft at first, but hardened up after a few pumps. Is this normal? No water. I am going to change it anyway.

My problem seems to be intermittent. A mechanic friend of mine said he has solved similar problems on several Duramaxes by changing the glow plug relay. An intermittently working relay would explain my problems, so I have one on order and it will be here tomorrow (Tues).

We have had unseasonably warm weather here (central interior of British Columbia, Canada) which has made it difficult to determine if the glow plugs are working or not. On the up side, I haven't had to worry about getting stranded at work where I can't plug in.

I will post again after I install the new relay.

Thanks for the help.

Mike

[turnpike]

If it is in fact glow plug problems, some of the dime store code readers will not pick up those codes. Get a good code reader that can read any of the modules in that truck. And let us know the readings.

The OP said something about hard starting..... cranks slowly,.... cranks too long of time,.... starts on one or two cylinders after a short crank then fires on more cylinders until all are lit????? Let us know.

A good code reader/monitor will save you money not spent on un-needed parts.

[Noladdermike]

My code reader is a little old, about 5 years, but it is a good one, it is an Innova 3120 and it cost about $250 back then. I bought it because it reads OBD 2 & 1 and my teenage boys were driving some older vehicles back then.

As for the cranking, it cranked quickly for a long time. At first no firing, then one cylinder started to fire irracticly until it started and then it ran rough for awhile, I can't say how many were firing when it started but it wasn't all 8.

I started it a couple of days ago when it was only a couple of deg warmer and it started perfectly, I need some good cold weather to really test it out.

Mike

[Noladdermike]

We finally got some cool weather this morning, the truck started right up and ran smoothly. Thanks for all the help.

Mike

[Dev11on]

Replaced batteries and glow plugs, still struggling.

[MTL_Dmax]

Originally Posted by Dev11on

Replaced batteries and glow plugs, still struggling.

Have you replaced the glow plug module as well?

If not I would be doing that next (easy to do and around $100).

[Noladdermike]

I haven't had any starting problems since I replaced the glow plug relay, we didn't get our usual cold weather but it did get down to -16'C (about 3'F). It was easy to do, it is mounted up near the turbo on my LLY, just remove it from the bracket because there is a plastic clip on the back that has to be opened. Is was $200 to $250 Canadian, I thought that was high for a relay but since it solved my problem and was easy to do I am happy.

Good Luck fixing your truck. Let us know when you get the problem solved.

Mike