Ok guys, I normally hang out in the Dentside forums but do occasionally venture into you guys world. I've got an issue with my brothers truck that has me scratching my head and thought maybe y'all could help me out. First of it's a '99 7.3 that has 280.000 miles on it, bone stock, maintained fairly well (not as good as my stuff, but not bad). This past fall when the temps started getting down around 50 degrees, he started having problems starting it unless he plugged it in. It had been quite a few years since he had done glow plugs so my first thought was to put glow plugs in it, which I did. 8 new Motorcrafts and new Dorman gaskets with the attached UVCH's. The new glow plugs have helped, it will now start at 30 degrees but does crank longer than it used to before this issue popped up. We haven't had temps lower than 30 since I put the new glow plugs in. Also, when it does fire, it gives a short, but pretty good puff of black smoke and runs rough for a few seconds then smooths out. It runs great once it smooths out and has the same power it has always had. This past weekend I put a new cam position sensor in it .......just because......which didn't change a thing. It kinda has me stumped now as to where to look. It has no check engine light and never has so I doubt it has any codes. Any good advise would be greatly appreciated!!!!!!

 

 

So you are saying the Dorman gaskets and UVCH are the problem? Glow plugs are Motorcrafts.......The Dorman gaskets came highly recommended by the counter guy at Advanced Auto........he said that Dorman had improved them and they hadn't had any issues....and yes, it still has the original injectors.

 

 

Whats the best way to test the injectors then?

 

 

Thanks!!! guess I need to find someone with that capability. Could it be a ICP problem? I had a no start condition on my '96 a while back.......replaced the Orings on the ICP and it cured it.......My thinking on this 99 is if Orings are just starting to fail, it may cause a hard start???? Or am I totally off base on this?

 

 

Have you checked or replaced the glow plug relay? If the new GPs aren’t getting the juice they won’t help very much.

 

I am for sure getting power to the valve cover connectors, I haven't pulled the valve covers back off to check for power at the glow plugs themselves. I am assuming I have voltage at the glow plugs since I replaced the VC gaskets with the Dormans that have the built in UVCH. Keyword I guess would be assume. So the GP relay is definitely working.

 

You can check glow plugs by monitoring your voltage when activating them. I have a cigarette lighter volt meter and mine cause about 1V drop when they come on. How are your starter and batteries? Cranking speed is an important part of the puzzle when starting a cold engine.

 

The glow plug relay can still be working but not efficiently. The contacts inside get pitted and corroded over time. You may not be getting full voltage / amperage to those new plugs. If it's original I would change it.


You can check voltage to ground from each of the big lugs on the GP relay with it engaged. Should be almost identical. If the glow plug side reads lower then it's not transferring all the energy across the contacts


The possibility of tired injectors is real with that many miles on them.

 

Yeah, I haven't checked voltage at the GPR.......just checked for power with a test light........good idea......Cranking speed seems normal.........not slow......

 

I second the GPR, I replaced all mine a few years ago due to hard starting, it helped but still nothing great. I checked the GPR and it was pass using a test light but it wasn't passing enough current to heat the plugs. I actually tapped it with a hammer and the truck fired right up. Replaced the GPR and all has been good.

 

Is it starting to use a bit of oil? At about 160k my '96 was starting to use some oil. Changed the injector o-rings, solved that. Leaking injector o-rings will cause low ICP causing hard starts, but, also at 280k, there is likely some poppet seat wear that causes the armature clearance to be reduced....causing a hard cold start condition.

And as others have mention, GP solenoid is another troublesome area.