Hey all,

I have a new one for yah. This is a more of a hard start issue rather than a cold start issue. Luckily it hasn’t gotten cold yet, but I have one of our fleet trucks being a PITA here recently. Little backround on this truck… Would absolutely not fire over the winter unless plugged in and would run on 5 of 8 injectors till warm…all 8 injectors except one were original factories at 218k. Figured we had sticky poppet valves and I did a handful of repairs on it as well.

8 months ago I replaced:
Glow plugs
UVCH
All 8 injectors- Premium rebuilds from Rosewood
New pigtails
Stancor Relay
6637 Intake
Full turbo rebuild and new wheel
Fuel Filter – rebuilt bowl
Brand new Motorcraft batteries
Coolant flush

After doing this the truck did not hesitate one bit to start on the first crank being unplugged in -20 - degree weather as long as I let the GP warm up for 10-20 seconds… I haven’t had a single problem with it till recently.
Here is the problem. Every morning when the crews go out to start the truck after sitting for the night, it takes quite a bit of cranking to fire after the GPs lite for a good 10 seconds after the WTS light goes out. I say 5-12 seconds of cranking and then it fires. Once it fires it fires right up. No sputtering, smooth idle as if it were hot.. Runs solid for the rest of the day and only happens first thing in the morning. Being the guy who fixed the truck originally I need to resolve this since the boss man is a bit unhappy about it.

When it starts it pushes a good plume of white out the tailpipe for a short second. Its unburnt diesel not coolant or something else… Fuel filter is still very clean, air filter is in great shape. Does not show this problem at any other point in the day. I have not checked fuel pressure but figured this would happen throughout the day if it were the case. I am going to ohm out all the GP again from the harness back. The only thing I can think of is the valve cover gasket pins are toasted. I know new OEM valve cover gaskets were replaced a few years back, but I’m wondering if the Stancor toasted any weak pins this summer. I did very similar work on my truck and did not do the valve cover gaskets and it turned just 2 or 3 burnt pins were causing all my headache.

So I ask you all what I should look into. I will get cranking fuel pressure on Friday morning, and ohm out the plugs as well. What else should I look for? I do not have AE to run a full diagnostic test so that is out of the question. I am really tempted to buy it now though. Taking care of 13 of these pigs from 95-2003 models is starting to be quite the chore.

Any help would be appreciated and I can relay any info requested.

Thanks!

 

I'd check the hpop red. in the morning to see if its draining down

 

I actually thought of that and have checked multiple times. Not a drain back issue I believe, and wouldn't be good reasoning for why it still puffs white a bunch at first...

 

How is its spinning over when cold ?
A slow spinning engine would cause this when cold

 

Spins just as fast as the other trucks...Newer batteries and a new starter as 9 months ago. I know its not a voltage issue or cranking too slow.

Like I said the only thing i didn't replace were those VC gaskets... need to get some resistance readings first to be sure and inspect the plugs and pins...

I just have a feeling its only going to get worse as the weather starts to get colder... Like is said no problems after the repairs even in the dead of winter this past year, Its just weird its doing this more and more throughout the summer... weather is plenty warm! Just not sure why its taking so long to start in the mornings...its the only truck that does this now out of the fleet, and I really try to stay on top of them maintenance wise.... Havn't seen this before so I'm a little at a lost

 

I agree that it sounds HPO related. how old is the oil? my truck started doing this sort of thing beginning of this summer - right at 3000 miles on Rotella T3. warm weather = thinner oil. but you say it doesn't do this except in the morning. how about if its started warm, but not hot - like after sitting for more than a few minutes but longer than an hour or two?

With me, I've been running Mobil Delvac since then and its been much better and quieter overall.

do you have a scanner to watch IPR duty cycle and ICP readings while cranking? that would answer those questions. but yes, it shouldn't dump any fuel into the cylinders until the proper HPO and other start conditions are met...

 

I don’t have a scanner and am seriously considering purchasing AE in order to properly troubleshoot these trucks. Only so much I can do without seeing what the truck is seeing.

Regarding oil… The boss has his regiment OCI of when he like to change oil and its not one I agree with, but I completely agree that it may be beat up oil. We run AMSOIL full syn in all of them. These trucks never leave the lot without 6-12k lbs behind them whether it’s a gooseneck or chipper, or trailer.

I guess until I see what numbers its spitting out I can only guess on the HPOP condition. I will say it’s one of the stronger running trucks out of the lot, even considering some minor blowby, and I’d at least think if the HPOP was weak it would be a bit noticeable, I have replaced a few of those and can tell the difference before and after, solely by butt dyno, which is not the proper way.

Maybe we can get it into the local diesel shop and see what they have to say regarding a scan and readings, but I sure would like to solve this on my own. I guess I can check resistance and then check fuel pressure, and voltage on startup…. For starters

 

Know you replaced the GPR a while back but I would suspect it before going deeper. At least slap a screwdriver across the terminals or check it with a volt meter.

 

Good point, I'll double check it as well, but Ill be damned if it went out in less than a year...

 

What brand of glow plugs?

Unburned fuel means it's injecting but not igniting, of course. Only two things come to mind - either the GPs aren't getting the chambers hot enough to ignite, or there's insufficient compression 'til it cranks some.

 

Where are yall located? I've got AE that I could send out to you.

 

In full agreement there. Motorcraft ZD-11s in all our trucks. I doubts its the plugs. I know this truck is down a bit on compression due to the CCV mod and the amount of venting once hot, a bit of blowby but I have seen much worse.

I guess before we go anywhere I need to test the GP relay and plugs, vc pins too. Next my voltage during cranking and fuel pressure during cranking. Then move onto getting a scan off the truck at a shop, or biting the bullet for AE.

Is Auto Enginuity the best diagnostic service out there still for the 7.3?

Wish I could convince him to change the oil to see if that it part of the problem. I can tell even at 3k to 3500 miles on T6 my truck runs different than with fresh oil.

let alone what he try to push them too.

 

I'm in CO. Is it something that I can simply install on a lap top and send back? Sure would save me some serous money!

 

What's the temps there ?
In the summer I would disconnect my gpr and never had a issue starting.
I'm haveing a hard time thinking its GP related in the summer

 

Low 50's, so that's why I'm also curious if this has anything to do with glow plugs or GPR as well. If they are not ligting at all I could see it to be a problem, but still makes me worried about compression or another issue, but its a place to start.