Hi everyone, the temps here in SW MO. have just started to dip into the upper 40's and noticed my 7.3 is hard to start on this cold mornings but on warmer days no issues. Batteries are 4 mths old. I removed the intake air heater assy. and Riff Raffed plugged it a few yrs ago so I know that's not it. My model does not have a separate glow plug relay, it just has the glow plug relay/control module. I have a Ford service manual which has it diagramed this way but the service procedures in the same manual picture a separate relay which looks like the heater relay I took out. Anyway is there anyway to test this relay control module?(long siver fined unit) I would think if it was bad it would throw a code but nothing. thanks, Charlie

 

I had a glow plug question and I was referred to the respective engine forum. Here is the 7.3 forum:

https://www.ford-trucks.com/forums/forum31/

Cheers

 

I'll move this down to the 7.3 forum, but before I do so, I'll offer a few suggestions.

You'll need to ohm out your Glow Plugs and make sure none of them are bad or weak. This will cause a hard starting issue when cold.

Though this has the potential to end with a trip below the valve covers, you would also need to make sure that the UVCH or Under Valve Cover Harness isn't loose of has burnt pins like I had.

If some glow plugs show as bad, replace them with motorcraft plugs and not anything you'll find at the auto parts store.

If someone near you has an Auto Enginuity scanner with the Enhanced Ford pack, you can get your answers without doing things manually and get a more direct answer sooner.

 

Charlie,
Since your truck is either a CA emissions-equipped truck or an Excursion, it has a Glow Plug Control Module or GPCM instead of the Glow Plug Relay or GPR that everyone else has.
If I'm not mistaken, a GPCM equipped truck will throw a CEL if any glow plug is bad. I'm not sure about the whole module, but I'd imagine the same would apply.
Your Air Intake Heater is a non-factor here, as it seems you already know. Certain parameters must be met for the AIH to activate, and they cannot be met at startup.

I'm curious about the relay you removed. Did you remove it at the same time as you deleted your AIH?
How long do you crank before the truck fires up?
Is there a lot of white smoke?

You may have codes stored that won't throw a CEL. Do you have access to Auto Enginuity or any other scan tool capable of reading codes on our trucks?

Hopefully this holds you over until more/better help arrives.

 

Sounds like a bad GPCM or relay if so equipped. I had a bad relay last year, and it still clicked just didn't fire up the glow plugs correctly. If it was really cold, and two or more glow plugs were bad, that could be the problem also, but you said it really wasn't that cold.

 

Hi all and thanks for all the responses. Yes the truck has the GP module not the relay. I took off the heater relay about 1.5 yrs ago and plugged it. I replaced all the glow plugs when I replaced an injector about a yr ago. It is fixed now and I'm embarrased to tell everyone what it was but I'm going to so maybe the next guy will avoid hours of troubleshooting and buying alot of unnecessary parts. IT WAS LOW ON OIL!!! (really low). I'm the original owner with 300K miles and this is the first time I've overlooked something like this. I know this to be true because to date all I've done is replace one injector and 8 glow plugs. Oil changes every 3.5k so I don't know what happened unless I just did'nt put enough in last time I changed it. It's about due for a change so I decided to check the color on the dipstick and that''s how I found the problem- there wasn't any oil on the stick. I know how dumb. I added oil and the other day it got down to 28* and it started right up. All solved, seems to be running good but I guess I may have shortened the engine life a little, time will tell, oh it was 6 quarts low, it hold 15! thanks