Hello all.. I bought a 90 F-250 7.3 IDI a couple months ago... anyways I been driving it since then and having no problems... untill today.. I took it on a longer trip today around 100 miles one way I believe it was.. and about 3/4 the way there it started to develop a miss while trying to maintain speed and idles perfect and when accelerating it doesnt seem to miss a lick either.. just when trying to maintain engine RPM.. I took a look down at the guages (stock) and showed normal temp and oil pressure. I also took a look in the right side mirror at the tailpipe and everytime it missed a puff of bluish smoke came out. So I then pulled over and shut it down and pulled the dipstick and when I added oil yesterday I overfilled it and it showed that it was still overfull... My question now is.. being it was a hotter day and running it a little bit harder then I normally do 65-70 MPH and it being overfull could it by chance be pushing oil past the rings and temporary fouling the cylinder with crankcase oil? or could it be something else? I checked coolant level and it's full and not contaminated that I could tell.. (need to get the test strips for it yet though) could it also be something as a bad injector or seal? let me know what you think.. I am a complete noob to diesel engines and this is kinda got me worrying

 

how much overful is the oil?
it sounds to me like a nozzle (injector) is acting up or there is air getting into the fuel system somewhere.
When you are driving down the road, the smoke from the exhaust is hard to tell what color actually is.
When it misses, does it shake the truck and can you make it miss while increasing the rpm while standing? When does the miss occur when standing at high idle? Does any fuel appear along the fuel return lines? When did it start this missing - after a fuel filter change or just during normal operation? Is the fuel filter leaking? Is there any leaks in the motor? Where?
The more info you can provide, the better help you can receive.
We can help, but, you are there and we are here.

 

Hello, Thanks for the reply

It's about 3/8 of an inch over the full mark. I looked for fuel leaks and didn't find any. have yet to replace the fuel filter but planned to soon. the truck misses on a free rev when holding the throttle down a little bit.. but idles perfect engine does Not shake even a little bit when idleing.. but when going to the road you can feel the truck surge when it misses. about the smoke, It will smoke a steady puff of whitish blue smoke when letting off the throttle.. and puffs just a little puff of smoke when it misses. "When did it start missing?" Yesterday on the way to where I was going and missed all the way back home. little bit I have come up with from reading is it could be a bad injector or Injection Pump. I was worried it could be cavitation But from what I read there are really no signs of it how it runs till it just up and pukes (hydrolock etc...) So my problems should rule out Cavitation right? my coolant level is full and the oil looks like all oil so that should rule out headgasket aswell.. How would I go about testing my IP? or is this something I have to bring to the Techs and have them check it out? I have also read that some type of fuel conditioner may put a bandaid on a IP for awhile is this true? and what fuel conditioner is supposed to be the best? Sorry for all the questions and I hope I have answered all of your questions.. Thanks again for the reply I hope we can get this figured out I sure would hate to trash my engine if it's not already junk..

 

Usually if the injection goes bad, usually it will weep from the weep hole in the bottom of the pump. The hole is located right where the pump mounts to the tower and on the bottom of the pump neck. You will need someone to jamb your finger under the neck to reach the hole (it is really a tight fit there) and you will see fuel on the end of your finger.
But it sounds like a nozzle to me. You can "short" them out one at a time to determine which one is bad. Using a 5/8 open end wrench you can loosen the injection line at each nozzle. They will leak fuel when you do this. The one that does not make a difference is the culprit. You will probably need someone to help you by holding the rpm where it is making the engine miss. You will have to loosen the lines slowly and wait a second between each one. Just go down the line on each side, no particular sequence. One side at a time. BE CAREFUL NOT TO GET TANGLED UP IN MOVING PARTS !!!!!!!!!!!!!!!!! If you have any doubts about doing this, have a tech do it for you.
You may have also gotten some dirt into one of the nozzles.
BE CAREFUL AROUND MOVING PARTS. Let us know how you make out.

 

One more thing.. Is it normal for the 7.3 to miss on a cold start? it's done that since I got it.. on a fresh cold start it would miss for a few seconds then if I rev it up a little it would smooth out.. I just figured this was due to the fact I have a couple glow plugs that are weak or shot.. I am gonna try the "shorting" the nozzle out trick.. maybe narrow it down to what cylinder it is missing on.. if the injector is dirty.. is there anything I can do to clean it? I am thinking not, right? I think if it comes down to it.. I am going to just buy all 8 injectors new and be done with it.. along with a install kit ofcourse.. then if it still runs like a pile.. I spose I will have to get a IP for it Just when I thought my truck was worth a turbo and oversized pipe.. ok.. another question for ya.. where is the cheapest place to get injectors? and is it a good Idea to get Rebuilt injectors or is it even cheaper to get mine rebuilt? I think there is a injector shop in town here.. I will have to give them a call tommorow.. Thanks for all the help thus far..

 

Depending on who you talk to new injectors seem to be the way to go. Ours are not near as expensive as the PSDs. For the fuel additive(and we should ALWAYS be using some) Stanadyne is great stuff. There are throngs of guys using the Performance or the Lubricity formulas. When you change the filter fill it up with one or the other and give the pump and injectors a real good dose of it and then add it to every tank when filling up. Four ounces for every fifteen gallons is what I'm adding with the Performance formula. Another option is Power Service Year Round Formula(same ratio in the tanks). Both brands will add lubricity to the fuel which our pumps and injectors must have!

On the cold start, our trucks will run rough until the cylinders warm up enough to burn the fuel better. It should smooth out after a few seconds though. Bad glowplugs can add to this. Be sure to use Motorcraft/Beru plugs. The Champions and Autolites have a tendency to short out quickly and sometimes the tips swell and can break off in the cyllinder and that may mean pulling the head to retrieve the tip.

On the miss, you don't have to have a visible leak to get air in the lines. If the return lines have been on there quite a while they may need to be changed and that could be your culprit still. Pretty easy to do and the kits shouldn't be more than $30 to $40. Be sure the fuel hose supplied is meant for diesel fuel!

 

remember the site, but I found OEM Ford injectors for $24.95 ea on the web. Now I wish that I had bookmarked the site! You could've used it, and I might later.
Good luck...my bet is the injector route and not the IP.

 

I would get that extra oil out of there. There are oil jets already spraying oil on the piston bottoms, and any extra oil spashing from the crank can't be good. It would be a helluva thing if you were fouling out a cylinder with oil.

I would try that first, you did say you overfilled it yesterday, and it started acting up today, right.