Well I replaced all the glow plugs, under cover harness, vale cover gasket, and relay on my 2000 F250 with new parts from Riff Raff. Four of my old plugs were bad, curiously all four were the middle two on each bank. I checked the wiring from the relay to the VC gasket plug, from the outside female pins of the VC gasket plug to the glow plugs and all was good. The new plugs all ohmed out at 0.9 before and after installation. Still crank but no start.
I noticed the tin nut on my IPR had loosened so I replaced both the IPR and sensor with new parts that I had ordered but never installed, also from Riff Raff. Still crank but no start. I should add that I replaced my fuel filters a couple of weeks ago when I started having problems.
I then disconnected the output terminal from the glow plug relay, pulled the air filter and gave it a very brief shot of starting fluid. It cranked right up, I put the air filter back on and I took it for a test drive. It ran smoothly with plenty of power, and came back home. I tried starting it 10 minutes later and it cranked and ran fine. A couple of hours later with the relay out put reinstalled it was back to crank and no start. I've repeated this two more times with the same results. This all leads me to believe that it's something in the glow plug system that I'm missing because when it's warm I have no problems starting it up.
Does anyone have any ideas to help me with this problem?

 

Have you verified that the glow plug relay is working and sending power to the glow plugs when you switch key on?

 

Plug it in for a few hours and if it starts then you know it’s your GP’s

 

The relay is passing power and cuts off after about 2 minutes.
I don't have a block heater on the truck so I can't use that idea. It's not cold yet, I'm in North Georgia and the temps right now are high 60s at night and ~80 in the daytime.

 

Check battery voltage before you switch key on and after. You switch key on. If the glow plugs are working they will drop voltage around 1 volt roughly if working properly.

 

HPOP reservoir draining down?

 

I haven't checked the voltage drop since I installed the new parts but it was ~.8 volt before, I'll check again.
I'll take a look at the reservoir and top it off if needed before I try a cold start and see if that makes a difference. If that's the cause is there a fix?

 

Since you had the valve covers off, did you check the harness that goes over the drivers side valve cover. Known to chafe from vibration and can short out against the cover.
if you have a code reader / tuner, run a buzz test on the infectors to be sure they are all firing evenly.

 

My tablet that holds the Ford programs is down so I haven't run a buzz test. The harness connector on the drivers side did not appear to be chafed or brittle when I checked it. As soon as I get the tablet up again (damn Google) I'll do the test and check for codes. In the meantime the engine is running too smoothly to indicate a problem with injectors.

 

at 60, it should fire up with out glow plugs needed, mine starts at 50 with out them

what cranking RPM do you have?
does low oil pressure come up fast on gauge during your first crank? Mine would not since my oil pump seal was gone and took 5-10 seconds of cranking to gain oil pressure

 

Agreed with above, at 60F glow plugs make no difference. A loose tinnerman nut on the IPR, that makes a big difference.

General "no start" stuff to check: oil level, fuel level, oil level in HPOP reservoir before start. Worth pulling the fuel filter to see if the bowl is full too. Note the color of the fuel.

And puh-leeze no more starting fluid! Could cause internal damage on a glow plug engine.

 

I started rechecking oil level, fuel level, HPOP res. level, IPR & sensor plugs and tin nut- all appeared fine. The truck was sitting in the sun ~ 76 F so I tried starting it and it started right up' I had left the glow plug main connector off the GP relay, just had the blue wire that I believe signals the computer that the relay is energized on the output stud. I tried it a couple of times and it started quickly each time. I then hooked the glow plug wires back up and no start. Next I disconnected the blue wire leaving the GP wires on the relay- no start. Then I removed the GP wires and replaced the blue wire on the relay- started right up.I'll try it in the morning when it's had a long sit at lower temps and see what I find but this is a real head scratchier for me. I didn't think to try it with both of the wires disconnected but will if it starts in the morning.
ANY IDEAS?

 

One other thought, does anyone have a wiring diagram for this circuit? I want to make sure each wire goes where it should. This is a 2000 F250 build date 8/99.
Thanks,
Lewis

 

 

Thanks for the diagram. If I read it correctly the blue wire coming off the switched power terminal is a fusible link feeding the PCM. My blue wire has a link in it so it is in the right place. The other two trip wires are on opposite sides of the relay and will only reach to their respective terminals so they are correct. The always on power wire is obvious so I have the relay wired properly.
At this stage I'm second guessing myself on everything. Now I have to figure out why the truck won't start with the glow plugs hooked up to the relay. I just tried it again after several hours of sitting and cooler temperatures (65 F) and it started almost immediately.