[jcm3]

My truck has been having a weird start behavior, especially when it's colder. I keep it in the garage, and since it's been warm, hasn't been an issue. But, the symptom is that it kind of struggles to start when it's colder, not like a battery issue where it turns over slowly, but more like it's trying to turn over but there's some resistance and it kind of stumbles, almost like it's misfiring in some way.

I assumed it was related to a few glow plugs being out, so this week I finished replacing the eight glow plugs, the two wiring harnesses and the GPCM. For the first time in about three years I don't have a check engine light, as the glow plugs are all good. I assumed that was the end of the starting issue.

Today I left the house early, and although it was not cold, it was in the 60's, and stumbled a little bit on the start. As soon as the engine warms up, it turns over super fast and starts perfectly. It's just when it's cold.

The two batteries are within a year or so old, and I did go for the AGM batteries. They seem good, and crank super fast when it's not cold.

I was doing some research, and some of the potential causes come up as glow plugs (all new), FICM (I have an upgraded one from FICMRepair.com, and it's still showing 50 on my Edge Insight CTS, and injectors. I assume my injectors are going to need to be replaced at some point.

Truck has about 184,000 miles on it
No check engine light or codes
I change my oil every 5,000 miles with Rotella T6
It has the revised stand pipes and dummy plugs

I was thinking about changing out the fuel pump due to the mileage, before it causes a problem.

Any thoughts, or ideas on how to troubleshoot to narrow down the issue? I'm worried that when winter gets here, I'll be screwed.

 

[jcm3]

Doing some more research, I'm feeling like it could be related to the injectors sticking when cold, based on some good info from these two articles:

http://swampsmotorsports.com/files/6.0%20FICM_updated.pdf

How to Diagnose a Bad Injector on a 6.0 Powerstroke Diesel Causing Poor Engine Performance, Bad Fuel Economy | National News Today | Expert Articles

One of the things I might try since I don't have any check engine light or codes is an oil additive to see if it helps. If it does, then it's probably short term and I need to plan to replace the injectors if I want to get more life out of this truck. I plan to drive it until it dies.

One is Rev X, anyone used it or have another opinion on a good oil additive to see if the symptom goes away or is reduced?

 

[Hydro]

I was thinking about changing out the fuel pump due to the mileage, before it causes a problem.

I suggest instead put a pressure sensor in the fuel bowl test port, that way you can monitor the fuel pressure
low fuel pressure will kill an injector

ForScan will do an injector "buzz" test, you listen to the sound of each injector for a weak sounding one
with your miles it may be getting time for new injectors anyway

When you first key on, do the injectors sound like they click evenly?
pop the hood and stand where you can easily hear them

 

[jcm3]

I suggest instead put a pressure sensor in the fuel bowl test port, that way you can monitor the fuel pressure
low fuel pressure will kill an injector

ForScan will do an injector "buzz" test, you listen to the sound of each injector for a weak sounding one
with your miles it may be getting time for new injectors anyway

When you first key on, do the injectors sound like they click evenly?
pop the hood and stand where you can easily hear them

Good info, I'll try those suggestions.

I agree with what you said, my plan (other than trying your suggestions) is to see if Archoil makes the cold start issue better, and if it does, then I know what it is and will plan to get the injectors swapped out.

 

[ChallengerRV]

I agree with Hydro. Put an actual gauge on on the fuel bowel to monitor before you spend $$ on a new pump. Looks like you are already thinking about trying the Archoil AR9100. It is well worth a try. I run it in my truck every oil change and so far I have not had any issues with stiction.

When you try to start the truck when it's cool does it seem like it spins a little slow? If it is maybe, it's not batteries but you might also check the grounds and the connections to the starter. They might be getting a little corrosion and not be moving the power they need to. Even if that doesn't solve the issue it is good maintenance to have done before winter set's in.