Cold start problems (funky GPR volts)

[Crbav8r]

Truck won't start below 40 deg.
Replaced glow plugs, and put o-rings on injectors(since they tested good)
batteries test over 1000 CCA
alternator good
new starter.

If I plug the truck up over night, it starts like new. Once it gets warmed up it runs like a champ.

I was testing the GPR this morning, and when the truck was cold I was getting 12v when I put the lead on the post. As it stayed there the voltage was jumping to 14, 18, 24, 51, 14... all over the place. This was on the glow plug side of the relay. The relay did shut off, but the truck still doesn't run. If it does, it lopes on like 4-6 cylinders for 30 seconds before smoothing out.

I had to shoot it with a little fire to get her going this morning. After it ran for 3-5 minutes, the GPR tested with 12.7 volts steady on the next start.

?????

Truck is 2001 F350 7.3 stock 248,000 miles

I did check the oil level in the HPOP, but it was after it had run a couple of minutes. I will check that tomorrow morning before cranking.

 

[Arisley]

I would replace the GPR.

 

[abbottfarms]

:whs: Best place to start I think.

And as I'm sure you know, be very careful about either on your engine, the off chance that your GP's worked that one time could have devastating results. I have used it on my truck a couple times, But I have disabled the GP's prior to doing so.

 

[JLDickmon]

sounds more like you got a screwy voltmeter.. replace the GPR though...

 

[Ron's Power Stroke]

if you have to use any thing at all..use WD40 rather then either..its little bit safer (but still not recommended with glow plug's) and has more lubricant for them cold cylinder's..

 

[dietoremain]

Ether is bad bad stuff. Replace the GPR and go from there man.

 

[PStroked444]

My truck was having similar issues. I cleaned the grounds for both batteries and the terminals on the GPR. Then went under the dash and cleaned the terminals on the ECU. The truck turns over faster now. Plus I think the GP's warm quicker. I will be replacing both the UVCH also. Maybe this will help? Good luck! :thumbsup:

 

[Crbav8r]

Update:
Volt meter(although brand new) "screwy"
Good meter showed 12.6 on the load side of the relay.
I replaced it anyway, and things look good. Haven't had a real cold night yet to test, but the 40 degree fired real good.

What is the best way to test current to the glow plugs, and not just voltage?
I was going to add the LED light to show when the glow plugs were burning, but this time it would have been a false light. The voltage was there, but not enough current.

CB