Missing/no power

[BDJack]

99 F250 7.3
Came out to start the truck yesterday, starts on third crank like usual, running like crap and shaking like it is missing or not firing on all cylinders. Then tried it another time, ran fine, drove it for a while. This morning, same thing, no power, missing.

Outside temperature does not seem to matter.Give me an idea where to start, I am at a loss.
Thanks

 

[DaveBen]

Plug it in to make sure it is not temperature related. Winter does this to diesels.

Dave

 

[jasonfrenchsr]

if i don't plug mine in at nite, it runs like a P.O.S.

 

[dachshund]

Do what Dave says first and if it starts fine plugged in we know it is either glow plugs or GP relay.

How many miles? How many miles on Injectors? Does it smoke while missing? If so, what color?

 

[BDJack]

130K white smoke if missing and I am on the pedal, otherwise none. In virginia, so would 30 degrees affect it the same as say minnesota, wis, other cold places some of you guys are from? I have never had this experience here with other dieselS, BUT.....

 

[dachshund]

Yes you will have problems at 30* if glow plugs are not working. First you need to check the GP relay. Of the two relays, it is the rear one. On battery side you should see 12 volts at all times. Check to see you get 12 volts on the other terminal when you turn the key on. Either have someone turn the key while you check or clip the test leads on or run around and test real fast. You need to do this when the egine is cold. If no voltage, replace the relay.

PS, I always check the switched power on the small terminal on top too just to make sure the relay is being energized.

 

[BDJack]

OK, I got to get ahold of a multimeter this weekend. It was 60-70 today, tried it, and it started shaking even worse, this time I noticed that the ligghts got brighter then dimmer, and this time it shut itself down, got a batt light and oil temp light.
Still think glow plug relay?

 

[BDJack]

PS, I always check the switched power on the small terminal on top too just to make sure the relay is being energized.[/QUOTE]

Which relay is it?

 

[BDJack]

Update

Plugged in the block heater to try and eliminate glow plug relay from possibilities. Truck would crank but not turn over, lights still going bright/dim/bright, so I am going to take out both batts and the alt and see what a bench test will tell me.

Not sure if the two could be related though, anyone tell me if a dead cell or a dying alt would cause the engine to run rough, like its missing/running short two cylinders?

(I searched and saw someone else had same question, no answer)

Thanks

 

[DaveBen]

You guys are talking about two different things. The plugging in of the Block Heater will have almost no effect on the glow plugs. Test the glow plugs as dachshund mentioned. Second, get your batteries LOAD TESTED at a good Auto Parts house or Garage. Get them tested independently, that is test each one separated from the other.

Dave