the problem started about a month ago the engine would start and idle just fine
but when it was warmed up and running at 55 then enigine would miss now and then.

then 2 weeks ago it started to miss more and also buck like a pissed off bull and finally die out. it would start up right away with no problem until the other day
i had to fight to get it home now when i try to start it will run for about 5 sec. and stop.

there was fuel in the fuel filter so i do believe the fuel pump is working other than that i am lost.

are there any ideas out there?

 

Dude there's alot to cover. I'd have to start with a buddy somewhere that has a good scan-tool and run a diagnostic test. Wish it were better news.
Bob

 

No port to install a scan tool on.
No computer to read the info from.

Has the fuel filter been changed recently?

Sounds like the IP is almost dead to me.


What year truck is this in and how many miles are on it?

 

LOL! How do you propose to hook up a scan tool? There are no electronics on a 6.9 to hook up to!

You said your fuel filter is working because the pump is working, so I presume you are referring to the lift pump (on the passenger side of the block).

First thing I'd do is make sure the lift pump is pumping enough fuel. Unplug the two wires on top of the injection pump to keep the engine from starting (one of them is the fuel cutoff). Remove the core of the schrader valve (looks like a tire valve stem) on top of the fuel filter. Use a jar or something to catch the fuel and crank over the engine. You should get about a half-pint of fuel out of it in 10 seconds IIRC. If it is pushing the right quantity of fuel, next connect a fuel pressure guage (they're under $20 from Harbor Freight) and measure the fuel pressure while cranking the engine. It should be around 3-4 psi.

If both those things check out, the next thing to look at is the output of the injection pump. Use a 5/8" open end wrench and loosen one of the nuts that attach the steel fuel line to one of the injectors. Loosen it about 1/2 turn and crank the engine. It should miss on that cylinder and squirt tint bits of fuel out of the nut - around the line where it goes into the nut. During this part of the testing process it is OK to plug the two wires back onto the top of the injection pump so that the engine will start. Have someone else start it while you watch for the little squirts of fuel at the injector line nut.

If the engine dies after 5 seconds (like it has been) see if it is still squirting fuel at the injector line nut when it dies and when you have your assistant crank it to restart. If the fuel isn't squirting at the injector nut then your pump isn't pushing fuel to the injectors. This can be due to a plugged fuel filter OR a dead/dying injector pump. Naturally you will want to try replacing the filter first, but if that doesn't fix it, then the injector pump will probably need to be replaced.

If the engine dies right after you start it and it is still squirting fuel at the injector nut when it dies and when your assistant cranks it to restart it, then tighten that injector nut and test another one. Go through them one at a time until you confirm that ALL of them are squirting fuel. If you have fuel to all the injectors, then the problem may be the injectors themselves, or possibly an injector pump that is worn to the point that the timing is varying widely - causing it to go so far so out-of time it won't run. Not likely but at least theoretically possible.

During all this testing there is one CRITICAL thing to keep in mind. Do NOT crank the starter more than 20 seconds at a time (which is a lot longer than it sounds like), then you have to let it cool down for 2 minutes before cranking on it any more. It is a good rule of thumb to let it cool a minute for every 10 seconds of cranking. If you crank for 5 seconds, wait 30 - 10 seconds, wait a minute - and so on. The starters are very heat sensitive and you can burn one up very easily. They are also fairly expensive to replace and a PITA to get in and out, from what I've read.

Good luck with it, and once you've completed these test procedures, post up the results and we'll see if you need more help....

 

sorry i thought i had posted that it was an 87 F250 must be a brain fart
as far as miles go that is unknown just have a feeling it is way up there and yes fuel filter was changed late summer

cheeperjeeper thanks for the info i will give it a shot over the week end and let you know what i come up with

 

Even though it was changed at the end of summer, don't overlook the possibility of a plugged fuel filter. If you've been running a biodiesel blend, or putting additives in your fuel (Howes, DieselKleen, etc.) you may have broken loose enough old deposits to plug the filter.

Worst case scenario is if you put a new fuel filter on it and that doesn't help, you can still hang onto the onto the one you took off as a spare. You will replace it again sooner or later. No real downside...

 

Sounds like a leak in the fuel line letting air in..check all your lines and the return lines at the injectors as well as the orings...

 

thought i post an up date right after i posted for help the temp dropped to about
-15 now that it is warmed up alittle(+20) the wind has kicked in 30 - 50 mph and you guessed it i have to work outside in the snow thanks again for all your info i will let you know how it turns out