2001 7.3l 390,000 mi Shell Rotella T15-40. tested the GP and GPR and both test good acording to all the post I have read on the issue so far and I have read almost all of them. 11.2 v consistantly on GPR both sides when activated Ohm on all GP is .6-.8 When I plug in the truck it will start fine but if I dont it takes 4 to 5 cycles of the key to get it to fire @25-35*F then lots of white smoke imediatly after starting and some while idling until the truck warms up. I typicaly do all my own work but this is something I can not figure out. Is there anything else I can test?

 

Have you checked the oil level in the hpop resevoir before and after cranking? A worn lpop can cause hard cold starts.

 

Ken also when you say you have voltage to both sides of the GPR with it in start postion how long dose the voltage last before turnig off. I had one on my van that wouldn't hold it long enough to heat the cyclinders so when I replaced it it worked fine. It should hold it a full 2 minutes with key on. If not its not good. If you can plug it in and it starts something in the Glow plug circuit isn't working. Your oil weight seems okay in your post.

Chet

 

I replaced the hpop 3 weeks ago and it holds voltage for a full 2 min

 

Good points! One other thing I was thinking is warmer oil is going to flow better and injectors won't fire until they see around 500psi.

The glow plug relay can stay on less than 2 minutes. The pcm can shorten the time based on temp and I believe barometric pressure.

 

Why did you change the HPOP? Have you scaned this truck with AE? Takes oil pressure to start also, what hpop did you put in? OEM, rebuilt? Do you have a gauge on it? Are you loosing prime? Maybe you posted earlier and I didn't read it but usually it is some kind of electrical thing so now I see hpop it makes me wonder.
Grant thanks for the response. I was thinking cold temp and hadn't been started which usually the GPR will stay on. God bless,

Chet

 

So are these original GP's? or have you recently replaced them? If you did, did you make sure to reconnect the wiring to the GP's? The 15-40 works well, but the Rotella T6 5w-40 is even better for the cold temps. Even still, if you have good GP's and a good GPR, even with 15w-40, you should start right up in those temps while unplugged.

Like previously stated, I would make sure that the gpr is holding at 12v, or near it for a minute or two. Even a fried GPR will spike to 12v and then go right back to zero, not allowing the gp's to actually be heated.

 

Sorry, just saw this. If you are refering to the GPR, then you are good on that note.

 

Not origional gp replaced passanger side ones a month ago the hpop i replaced because of the milage on the truck and it was leaking oil in several spots. yes the grp holds 11.2 volts for a full 2 min. yes all the plug harnes has been reconected and all the plugs now test .6to .8 ohms

 

Someone will correct me if im wrong but you shouldn't see any voltage, near 0 on both sides of the GPR when activated. If you are getting 11.2V this means that there is an 11v drop between the red lead(where you starting with the volt meter) and the black lead. Meaning that there is no voltage actually getting to the glow plugs. If you have 0v between the 2 big leads that means the GPR is actively working and sending the 12v to the GP's.

Try this cause i assume your getting 11.2v from the signal leads of the gpr. Which would probally be enough to activate it. Put a volt meter on the big leads of the gpr and without key in ignition the voltage drop between the two should be system voltage ie. battery voltage. Once you turn the key on, if the gpr is working corectly, that voltage you see across the two big terminals should go to near zero. If it doesnt, the gpr is bad. I just did this on mine to make sure i was correct and mine held like few mili volts for approx 2 mins. Then i heard the relay click and it went back to system voltage.

 

Negative. When voltage is showing on the gpr, the gp's are being heated.

 

He is talking about measuring across the two big terminals. So that is different than measuring from ground to the big posts. I read the OP was taking a measurement from ground to each big terminal. So not sure.

Have you done any injector work? How long have you had the truck? A scanner would help a lot. Most popular around here seems to be AE.

With that many miles a compression check would also be a good idea.


Another check is for blow by. Here is a generic check: 7.3l PSD Oil Blow-by - YouTube

If the cap does not blow up that is good news.

 

So your saying that there should be voltage on the two big terminals which are the heating side of the gpr, when the key is just turned on? Now that cant be right. That would mean there is a voltage drop. Meaning no voltage is making it across the gpr. Now yes, you should see voltage on the signal side of the relay. Which are the two small terminals. But I just tried mine not long ago. 32 degrees out, hasnt started in two days. 12.4v across battery terminals/big terminals of gpr before ignition on. Once ignition on, 25mV which is next to no voltage meaning no voltage drop and all battery voltage is going to the gp's. Truck started on a dime and no smoke. So...We are getting our ends crossed somewhere here.

Yes, if you are measuring the voltage from the battery terminals of the gpr to ground then 11v is acceptable on both sides. Sorry for the mis confusion.

 

I bought the truck in july this year to my knowledge there has been nothing done to the injectors. i do have a ts 6 position on it but that should have nothing to do with starting. i just put it in 2 weeks ago and it had trouble starting before that.

 

I wonder why they sold it that time of year.