Just went through a GP changeout with another FTE member here last weekend. He was experiencing a hard start and grey smoke condition on cold mornings. He has good batteries and a stancor GPR so we tackled the GP's. He just reported back that things are great. Honestly, we could not see any of the old GP's being physically "bad" - broken tips, wires etc. - but it was his problem.

Here's the link to that thread.

https://www.ford-trucks.com/forums/9...low-plugs.html

You might want to PM Andrew and pick his brain on his issues. Hate for you to pull the VC's and swap GP's and have it not be the problem. Good luck and keep us posted.

 

Thanks Ponyboychris

I just PMed Andrew. How hard of a job is it? Any special tools?

 

Hey Tom, just PM'ed you back but wanted to post here as well. There are no special tools needed per say, but a small tube helps to get the glow plugs out. From what you told me in the PM, I would be curious to hear how fast the starter is turning over. I don't know how big and effect a slow start has but I would assume that the truck wont start very easily with a slow one. If the start is spinning fast, then I would put money on the glow plugs being bad.

 

I to find it hard to believe that all 8 Gp's are dead

Did you take the batteries in to get tested ? My Dad had a similar occurrence.. he took in his batteries and they had 12v. But very low cranking amps.. Did you try jumping with another vehicle? That would give you more battery.

Glow plugs are easy. Getting the valve covers off is the hardest part. Once the covers are off it is easy swap out the GP. I used just a pair of needle nose to reach in to pull the gp's out and to install. And a deep socket and torqued them.

Good move on the stancor though.. You will never need another one..

 

Another thought

When you ohmed checked you valve cover connector what did you get on the injectors?
The injectors need to be checked against the "Common" center connector.
The Glow plugs need to be checked against ground (battery ground)

I know how hard it is getting in there with the gauge trying to hit those tiny little pins laying on your stomach. If you lived closer i would run over my tool. It moves both valve cover connectors to the front deck were you can ohm check both sides easier.

 

A few u-joint socket adapters and wobbles will help with the V/C removal as well. And Andrew and I managed to break his plastic heater hose brackets on the passenger side. We've done that twice now. Not sure what the hey we are doing wrong but they won't pop off the V/C bolt to save our life. Not a bad job, just time consuming. Be careful not to loose grip of the glowplug when installing. They can fall into the opening for the pushrods if you are not lining them up right. Don't ask me how I know this.

 

Thanks for all the help. I wish I could figure out what I am doing wrong on the resistance test for the GPs. Should I be going to battery ground or chassis ground? I tried testing the resistance on the injectors this morning as per Dan's suggestion. I put the black lead on the center pin of the passenger side valve cover connector and checked the 2 pins next to it on either side one at a time and I get 0 ohms. WTF? By the way, Nice setup Dan. That thing must make life much easier. I emailed Clay at RiffRaff Diesel, He has great prices on the motorcraft GPs. If I finally figure this out and decide to tackle it I will do the CCV mod while I'm in there.

 

Battery ground or Chassis really don't matter with measuring the GP's. I use the battery. I have done it both ways though. The readings will only very ever so slightly, if any.

You have to read the Injectors coils using the Center pin as common. It is isolated from the chassis/battery ground.

Honestly i would figure out the measuring ohm thing first. If you get it figured out and find out all 8 GPs are ok. It will save you a ton of time. Plus Injectors at 0 tell me something is wrong with the measuring especially sense the truck runs.

 

Thanks again Dan. I'm gonna have to figure out the ohm measurement thing. I used two different multimeters and have some experience with testing electrical connections. I cant figure out where I'm going wrong but I will.

 

I wrote the Information I learned about the 7.3l GPR test on another forum. I had a problem with the GPR and resolved it. I looked for a month or so asked a mechanic, Just compulation of good data. Getting good information in one place on this subject was tough. This is what I collected.
http://www.truckforum.org/forums/for...tml#post145786

Hope It helps pinpoint your 7.3 GPS issues.

Dave

 

I and a couple of friends had this same issue. As it turned out to be a burnt out GPR. With the truck in park and parking break set, open the hood, get something to stand on to reach the center top of the engine. You need to test both of the big wires on the GPR behind the fuel filter bowl and toward the fire wall the center of the the engine. Turn on the key to run, check both sides to ground both should read 12V If one dose and the other dose not. check to nake sure that both sides of the smaller two posts have 12V, thats the side the control side of the solenoid if you have power there it shows the key is giving power to the solenoid and the solenoid is not engaging
When I replaced my GPS. I took the old GPS apart the Copper disk that bridges the two large contacts had detonated nothing left. The post going to the GP's had detonated as well. (Arc Flashed) Nothing there! the inside of my GPS was thousands of ting copper ***** which were once a solid post and disk.
A friend recommended this site to me for my fuel bowl filter and fuel bowl drain valve rebuild parts. A lot cheaper and have done me fine for 3 years so far. Try
dieseloring.com they sell a #16-009 White-Rodgers (Stancor) 586 902 Monster Glow Plug Relay $56.49
it specs are rated for 12 volt continuous duty. Contact rating 200 amp continuous, 600 amp inrush.
Monster White-Rodgers Glow Plug Relay
this part is bigger than the OEM GPR but $30 cheaper than Ford parts and is rated to handel a bigger load. It's all around just a lot more robust.

Just FYI.

 

Silly question...but when you are measuring the resistance, obviously you are switched to the resistance setting, but are you moving to the right one? My MM has 7 different setting for measuring finite levels of resistance. If you are set to a level looking for 2k, 20k, 200k, etc...then something only putting out .5 to 1.0 may indeed only show up a zero. But you may already realize this...just checking ;-)

I don't know much about GP's and the relay, but zero ohms is a dead short...that don't seem like it can be the case for both your GP's and your injectors?

 

best thing to test the relay from what i have learned is just a test light simple and it will tell when its sending power ohms test requires to many numbers you have to figure out its either sending power or its not