I have a 86 F-250 w/6.9. I have the old style screw in type controller. My first controller when I bought the truck was on for 5 seconds and cycled for about 60 seconds. I replaced it because 5 seconds was not enough time to warm the plugs.

My second controller goes on for 8 seconds and then cycles 4 times and shuts off.

My third controller goes on for 7 seconds and cycles 4 times and then shuts off.

My glowplugs are getting plenty hot, but they are not cycling long enough for the cold weather. My question is what keeps them cycling? The contoller or some other component? I highly doubt it could be 2 defective controllers in a row.



1986 F-250 6.9 diesel,4x4,XLT Lariat,Ex Cab, 8'bed,etc...

 

I think this a perfect spot to post my very similar question. I have a '94 with a 7.3L IDI turbo diesel and I have not yet seen the glow-pulgs "cycle". I haven't timed how long the glow plug light stays on, but all I have ever noticed is that it goes on (probbably for 5-8 seconds) then shuts off. I'm assuming the light should flash when the glow plugs cycle? I think this could be a problem or just real annoying because even in about 70 degree weather it is VERY hard to start unless the engine has ben running for a while before. Another question which doesn't quite fit in this section is about operating temperatures, I have never seen the temp needle on my Ford or my dad's Dodge go more than about 1/8 the distance across the temp guage(ie: both needels stay about very close the cold mark). Does anything that I'm writing seem unusual?

Logan

 

How do you know they are getting plenty hot? (I'm not questing your integrity -- just trying to find out how you know that). The glow plugs pull about 30 amps each so the first click of the controller should show about a 320 amp draw. If you have some glow plugs burnt out or for some reason not cycling you will get a "short cycle." Also if your controller is no good it may or may not short cycle (usually it won't do anything but if the controller thinks the engine is hot when it is not it may also short cycle. The wires that connect the glow plugs on the IDI engine are fuesable links so you need to check those too. There is really not too much to the system -- the wiring harness, the glow plugs, and the controller. Check the easy stuff first. Check the wires and the pins in the plug at the controller, the glow plugs, and make sure the system is getting plenty of power. Also make sure the ground strap at the rear of the cylinder head has a good electrical connection. If everything checks out the controller is bad. Those screw-in controllers were a pain in the **** which is why Navistar designed a solid state controller for later models.

 

 

While I finally took my pick-up to the Ford dealer and another glow-plug was replaced for a total of 4 new glow plugs installed in less than 1000 miles.

Logan

 

I'm no certified mechanic, just a shade tree mechanic. both the 6.9 and the 7.3 idi are as simple as it gets. guys we can still work on them without the dealership involvement. and realitivley cheap to fix. mine is just rolling over 200k. to test your glow plugs, take the lead off of the glow plug, run your volt meter from the hot side of the battery to the top of the glow plug. if it shows 12 volts glow plug is good. less or none, bad or getting there. glow plugs run 10 buck a pop, and very easy to replace. the sensor (controler) at the back of the manifold is a little pricey, but again very easy to replace 100.00. and the piece on the fender well also again very easy is realitively cheap again. didn't know about those fuse links, will have to check those out next time. I replace glow plugs 4-5 every year, no big deal. my thoughts are that if you don't replace and make the remaining few start motor, everything has extra stress and will eventually create long term problems. it gets cold here, and mine will start in the coldest weather 10-. with a little thought, everytime, as long it don't gel. get out the gas/deisel line anti freeze, then the problems go away. gets really cold?? try a gallon of gasoline with a full tank of deisel.

85ranger club cab 6.9 headers, 4x4

 

While, unfortunatley I'm not as good as a mechanic as I would like to be. I find it a lot cheaper(sometimes), easier, and sometimes faster to get work done by a dealer. Also, being a home mechanic could probbably cause problems with your warranty. So yes I agree a lot of problems are cheap, and easy to fix, but for me I would have to buy all the extra tools and then buy the part itself, which could become costly for something I might only do once or twice.

Logan

 

I used to have numerous problems with the glow plug controller located at on the drivers side rear of the 6.9 engine. This device must be replaced by someone with experience or if installed improperly it will fail within a very short period of time. The Ford dealer should have someone, a certified diesel mechanic on staff that is familiar with the 6.9 or I would not let them work on it.
The reason that I say this is because our local dealer DOESN'T really have one and they changed that same sensor two times in a row and yes they did charge me the full amount every time. Since then, a diesel mechanic friend of mine designed a system that works much better than what the Ford engineers thought of and it has been over 5 years since I have had to replace any glowplugs..........No kidding.