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Discussion Starter #1
Hey guys,

Been lurking and reading since I bought my '04 a few weeks ago (lly, 135k miles).

I am having some issues on cold mornings with starting. Batteries are new as of about a week ago. When it gets cold at night truck won't start. Cranks and cranks but no go. This morning the ambient temp was about 22 but the windchill was about 5.

I have two thoughts here: glow plugs/controller or fuel filter. I am not sure though because it runs great the rest of the day after that first start in the cold. I have been doing some reading about how to test the glow plugs and controller but can someone give me an abridged version on how to test the controller? To test the glow plugs I have just read to test with meter and look for resistance. They are all around 4-6ohms. Glow plug relay is good.

Thoughts? This morning it did start after I primed the filter a few times. It did not start right up but did hesitantly start after that.

Seems a bit too warm to have to plug in...


Thanks!
 

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Windchill won't have any effect. When was the fuel filter last replaced? Are you running any kind of winter fuel additive? Does the glow plug light come on in the dash, if so how long before it goes out? Do you know what kind of oil is in it?
 

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Discussion Starter #3
Unsure on when fuel filter was last replaced. It was not in the last 1k miles I can tell you that based on looks. I am not running any winter additive at the moment.

Glow plug light comes on when starting. Later in the day you are lucky to catch it but it does come on, just goes off really fast. In the morning when hard starting it probably comes on for about 2-3 seconds.

I will check records for what oil the dealer put in (bought there and they had changed it). I should note that my neighbor has an '06 and has not experienced any issues. He has never run additive and has his oil changed at that dealer. Just to try and hold a few other things constant.
 

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I would try replacing the fuel filter. If priming it helps get it going I'd lean more towards the filter.
 

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Discussion Starter #5
Can do that. The reason I was leaning toward glow plug issues is because if I let it sit after not starting, it starts right up when it is warmer out.

Go home for lunch and it would start right up, no priming needed.
 

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Discussion Starter #6
Thought I would update.

I have a fuel filter coming but I had some time. Verified I had power to my GPCM and that wires to individual plugs had continuity to plug on GPCM. I tested resistance and voltage for all glow plugs again. All resistances were < 6ohms and voltages were right around 3-4.

Tested fuel heater power and ground for connectivity and resistance. Checked to be sure the path through the heater was functioning (getting power all the way through to the ground). Everything there looks good.

Waiting on filter to get here in the morning.


On a side note, what temperatures should I start having starting issues if everything was running fine? When is it cold enough to plug in the block heater? Manual says 0F I think. Anyone think of anything else I should have tested prior to putting in a fuel filter? I am new to diesels but very familiar with gas vehicles/electrical stuff so any help on the diesel stuff is great.

Thanks.
 

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Discussion Starter #7 (Edited)
Alright, update.

Got the fuel filter in yesterday. Got it primed and it started right up. Just drove it into town and back and everything seemed good. After I got back home I was cleaning up the garage and let the truck cool down. During this process I primed the fuel until hard and went back to what I was doing. Checked again after about 2-3 minutes and I was able to put about 2 more pumps in.

This morning it was not terribly cold, maybe 18. Tried starting it and it wouldn't go. I turned the key over 3-4 times and it started.

I want to re-emphasize this part: This problem only happens when being left overnight and the ambient temps get below about 18-20 degrees. If it sits overnight and it is 30 degrees when I go to start it, there is no issue and starts right up. If it sits during the day while I am work and it is 15 when I go back out, no issue.
 

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Somebody correct me if im wrong but you should not have to prime it... the only time I have ever primed mine was when I changed my fuel filter. My thoughts are to get a fuel filter housing rebuild kit from one of the vendors on here. Also use your bleeder screw to make sure all of the air is out... Have you checks for leaks?
Another thought.. Does the truck crank over slow? The fuel has nothing to do on how fast the truck cranks over (yes on how fast it starts)... Just a couple thoughts..
 

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Discussion Starter #9 (Edited)
I did that yesterday after the filter change just to see how long the priming bulb would stay hard.

I have not checked for leaks yet. I think that the fact that this only happens, basically after sitting over night and having cold temps, is making this either harder for me to diagnose or harder for me to wrap my head around the parts failing.

Batteries are good, if that is what the part about speed of the truck cranking over. They are new a few weeks ago.
 

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If you are needing to prime it on a daily basis you probably have worn filter head o-rings. Get a filterhead rebuild kit and that should fix it. Is this a recent purchase? If so, take it back to the dealer and see if they will fix it.
 

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Discussion Starter #11
Thanks js05sierrahd. I ordered a rebuild kit from dmaxstore.com. It is a recent purchase but I ended up purchasing this one down in Denver (I live in Laramie, WY). So I have to weigh the 2.5 hour one way drive too.

If this does not fix the issue I will have to take it back down. The real problem is that it does not get very cold in Denver this time of year so the problem may not manifest for them. Want to exhaust the relatively easy things before spending the time getting it down there. Maybe have my local GM dealer try and diagnose it this weekend if the rebuild kit doesn't fix it.
 

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Honestly I'm not sure if the temp is really a factor. Sounds like its just the amount of time the truck is sitting between startups. If you want to rule out the temp can you park it inside somewhere (may be easier said than done). Have you tried plugging in the block heater?
 

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Discussion Starter #13
If it is 30 degrees in the morning, at least before the fuel filter, there were not any starting issues.

We do not have a heated garage so that idea is out. Tonight I will plug it in though and see what it does. I wanted to test it this morning without plugging it in.
 

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even if the garage isn't heated you would be surprised how much warmer it will be than outside. I know mine stays around 40˚F when its in the 20s outside.
 

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Try pumping the primer BEFORE doing the cold start of the day.

Your truck should EASILY start in +20F, NO block heater needed.

BTW, My LBZ starts at -20F Ambient WITHOUT the block heater and lights up without ANY hesitation or rough running. Glow plug light stays on for about 6-8 seconds in those temps on a cold start.
 

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Try pumping the primer BEFORE doing the cold start of the day.

Your truck should EASILY start in +20F, NO block heater needed.

BTW, My LBZ starts at -20F Ambient WITHOUT the block heater and lights up without ANY hesitation or rough running. Glow plug light stays on for about 6-8 seconds in those temps on a cold start.
I was just about to say the same thing... "Try priming it BEFORE"
 

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Discussion Starter #17
So no real good update for today. It was 35 degrees (all temps I report are via the trucks thermometer) when I started it this morning. It took maybe 1/2 a second longer than a normal start (normal being what it starts like in the middle of the a typical day).

I have a rebuild kit coming and will be here tomorrow. Cheap enough anyways. It is supposed to be cold out for the next few nights so expect to see plenty more posts as I (we all) work to resolve this issue.


Thanks again for the help so far.
 

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Discussion Starter #19
Well it was 20 degrees this morning. I primed the filter before starting. No help there. It did eventually start but it took quite a bit of cranking (20+ seconds worth).
 

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I have the same problems rebuilt my fuel filter head Wednesday and still have the same problems. I have to prime it then it starts then stalls out after about 45 seconds
 
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