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Hard to Start - Glow Plugs
Ok guys, i figured i would post this up because i've had some issues with my truck starting hard since fall and winter weather has come. I already fixed my issues and got my truck running great but thought i would post this up for anyone else that may be having similar problems.
I have a 99 F350 7.3L Diesel. The truck was starting hard around anything less then 45 degrees, If I plugged it in the truck would fire up no problem. I checked the Glow Plug Relay and it was functioning properly, I also changed out my fuel filter during this time as well. After talking with a few people, someone had mentioned that maybe i should try some injector cleaner, and since injector cleaner was cheap i decided to start here. After running a tank of gas through with the cleaner I noticed the truck was running better and it seemed like my starting problems had dissapeared. However this was around fall time approx 45-60ish degree days/mornings. So i stopped plugging the truck in and it was starting fine.
After a couple weeks the hard starting came back because now the temps started to take a dive, to the point of this week where I've been having 30-10 degree mornings. Finally the truck was just becoming nearly impossible to start. The way I could get it fired up was to cycle the key and wait for the WTS light, and give it a quick crank. You could tell the truck was trying to fire but wouldn't start. So i would cycle the key and wait for the glow plug cycle and crank again, rinse and repeat untill it started. My first thought was maybe i had a "couple" bad glow plugs. I also got white smoke out of the exhaust while doing this so i knew i had fuel.
Finally i broke down and said it was time to investigate and check these glow plugs. I tried doing the resistance check on them by pulling the two plugs off the valve covers and putting one lead on negative side of battery and the positive on each pin for the glow plugs, I wasn't getting any readings at all. Not even infinity on my meter, so i touched the block/another ground source on my engine and my meter got a infinity reading, not quite sure why i wasn't getting anything on the glow plug, but i decided to just go pick up some new glow plugs and change them out. When i got the old ones out i plugged all 8 into one connector and just ran a jumper from ground to the sleeve on the plug, cycled the key, got nothing on all 8 of them. So i was pretty much convinced they were dead, so i also grabbed a new glow plug and tested it, which the end turned cherry red, now i knew they were definately all bad. Swapped the glow plugs out, and now the truck starts like a dream.
Hope this can help any of you that are troubleshooting your truck too.