[font color=red size=2]I'm having some trouble with my father-in-law's pickup - '86 F250 4x4 6.9 C6. I'm the 'family mechanic', but I'm not too bright in the diesel department, so I need your help. It seems to be flooding out. It only starts with the pedal to the floor, and it must be held at a high idle for about a minute or it will die, after minute or so it will idle (roughly). When running (cold or warm) it misses bad, weather idling or reved up, and lots of black smoke. It's been missing like this for the past month, but is steadily getting worse. It won't start when it get's below 10deg, even when plugged in. Runs the same when cold (20's) or warm (60's).

It has 130,000 miles on it, injectors were cleaned (2 replaced) last summer. Factory rebuilt injector pump with 200 miles. Glow plugs are good and seem to cycle correctly. Have tried #2 and blended fuel from several different stations with no change.

I would appreciate some help - what to look for and how to trouble shoot it. Thanks.


Marty

 

Sounds like you have a leaking injector. Black smoke is fuel.
Use a 5/8ths wrench and back off the fuel line retaining nut on each injector, one at a time and check for a differance in rpm/sound. It is kind of like pulling a plug wire on a gas engine to look for rpm drop/miss. But you only need to back off the nut about a half turn.
good luck.

 

Just curious. Has it been doing this since the injector pump was replaced? I replaced the injector pump on my 90 7.3, and it started doing the same thing. Mine was not nearly as bad. Turns out the pump timing was advanced too far. Could be that is your problem.
Craig

 

[font color=red size=2]I will try checking each of the injectors, and see what I come up with.

It did act this way before the pump, then it ran fine for awhile after the new pump. Now it's back to acting bad again. I'll also try the timing, it was timed by ear - so anything is possible.

Thanks for the replies, I appreciate the help...


Marty

 

There is a water seperater on the fire wall that you might check. I have never seen one full of water so I don't know if it could cause your problems or not.

 

Well, I got a chance to work with it again, I'm still stumped.

I checked each of the injectors like you suggested, each one changed the engine idle, making it miss and slowdown. So am I to assume that the injectors are working correctly?

I also checked the timing, it was turned completely to the passenger side. So I loosened it and turned it to the center of it's adjustment. It made no difference in how it runs.

I don't know about the water separator, I didn't get a chance to check it. I will do that.

I took it for a test drive today. It has no power as I'm driving, but then it revs up and 'ZOOM' lots of power, then goes back to weak and missing. It's not a slipping transmission - the tranny is good. It's definitely in the engine, something changes that gives it a burst of power for 10-15 seconds. Could I have gotten a bad pump? This is how it was acting before the pump was changed.

I would appreciate any help, I'm not to familiar with diesels, so I need some help. This truck is really starting to bug me... I gave it a good threat too " right in the grill!" but that didn't do anything...

Thanks.

Marty

 

Check the flow and pressure of the lift pump (looks like a fuel pump for a gas engine lower front of the block). It sounds like it is starving for fuel to me.

 

MSTA999 said "black smoke is fuel" which may be right but it could also be getting fuel at the wrong time or it could be a lack of air (probably not the problem in your case). If your lift pump is delivering the proper amount of fuel at the prescribed pressure, you've got something wrong with the injection pump (whether it has been rebuilt or not).

 

[updated:LAST EDITED ON 20-Mar-02 AT 00:44 AM (EST)]Just a thought, try unplugging the sensor on the intake manifold. It is at the right front. See if that makes a differance. Did on a 7.3 I was working on once. It is like a cold temp. switch.

Every time I have replaced and injection pump, seems like I always have to turn it a little to the drivers side, which is hard. There is a line in the front mounting flange of the pump and a line on the engine. Most of the time the line on the pump is a little to the drivers side of the line on the engine. If you are timeing it by "ear", when you put the throttle to the floor and it runs rough and smokes, it is too far one way and if it runs rough and doesn't smoke it is too far the other way. You have to find the middle, runs ok and not too much smoke. just FYI. Also make sure it is getting enough air. A plugged air filter will give the same symptoms you are descibing. Good luck.

 

I'm not too familiar with this engine but don't the injection pumps have to be "dynamically timed" with some sophisticated equipment?

Les

 

"Check the flow and pressure of the lift pump"

How do I do this? Do I need a special guage for it, I have a fuel pressure guage for gas with a rubber hose on it, would that work?

If it were a gas motor, I'd say it was flooding, because you HAVE to hold the pedal to the floor when starting or it won't start. With a diesel, does that signal not enough fuel? Like I said - I'm not to quick with diesels yet, I'm learning though.

Thanks for the help guys, I really appreciate it.


Marty

 

Well, I think it is solved. I talked to several different diesel mechanics, they all said they would put money on a bad lift pump, saying it was starving - not flooding (ageeing with The Diesel Dude). So I went ahead a replaced the lift pump. I've been driving it for 2 days and it's running great so far... Good start, smooth idle and no smoke (no more than normal). I think I got it!

Thanks to all for their help. I've learned alot about diesels the past few weeks.


Marty

 

Glad to see you got it figured out

Les