6.9 Hard Start
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New User
Joined: Aug 2003
Posts: 15
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From: Houghton, MI
6.9 Hard Start
I have a 1984 F250 (6.9 L)that recently has been giving me trouble starting. This summer the truck started fine, but now that it is getting colder I have erratic cold start problems. I checked the glow plugs when I first started having problems and found 4 were bad. It did not seem to help much to replace them. I can get the truck to start with extended cranking and putting the accelerator to the floor and she usually sputters to life after 3 or 4 cranking cycles, during which she spews a lot of white smoke (unburned fuel). At first I thought it could be air in the lines because one of my injectors leaks very slowly, or possibly a lift pump problem but if I get it to start and idle before heating up and shut it off, It will hard start again. A few questions to help me trouble shoot (i have never owned a diesel)
Will a diesel start normally with bad glow plugs during warm weather (70's)?
What is the normal glow plug cycle time range (wait to start) in seconds?
Can you "flood" a diesel like a gasoline engine?
How do you check the glow plug controller/wire system for problems (what is the normal resistance and or voltage at the glow plug clip)?
How tight should the connector clips be on the glow plugs (mine have a bit of slop in them could this be a problem)?
What symptoms would a bad lift pump cause?
Any help is appreciated.
Will a diesel start normally with bad glow plugs during warm weather (70's)?
What is the normal glow plug cycle time range (wait to start) in seconds?
Can you "flood" a diesel like a gasoline engine?
How do you check the glow plug controller/wire system for problems (what is the normal resistance and or voltage at the glow plug clip)?
How tight should the connector clips be on the glow plugs (mine have a bit of slop in them could this be a problem)?
What symptoms would a bad lift pump cause?
Any help is appreciated.
Senior User
Joined: Jul 2003
Posts: 166
Likes: 1
From: Aviano AB, Italy
ok I"m completely lost on diesels too but I think I remember hearing that on the old ford and old chevy systems if a glow plug go's out it takes out the controller and solenoid with it you might check them. I'm probly completely long about that and someone will correct me if I am but I think I might have heard that 
Do you have a Hayne's manual that should tell you how to test the controller and solenoid.
good luck with it sorry I'm not much of any help
Do you have a Hayne's manual that should tell you how to test the controller and solenoid.
good luck with it sorry I'm not much of any help
all alone in the world
Joined: Feb 2002
Posts: 2,038
Likes: 1
From: oklahoma
been a while, but i will give it a shot. it sounds like the glowplugs are either not working at all, or are not staying on long enough. the timers\ controllers are notorious for this. if it is the timer, i think the replacements are the 7.3 version. a better timer. could be a bad relay also. use a test light and check the output terminal on the relay with the engine cold, turn the key on and see how long the light stays lit. if it doesnt light, but you can hear or feel it click replace the relay. if it is not clicking, check the wires and make sure they are ok. use an ohmeter on the wires to make sure they are good. yes deisels will start fine in warm weather without the glowplugs working. the white smoke you see is fuel that is not burning. hope this helps some.
