6.9 running poorly

[dbryan]

Hi there,

I am new to this fourm and to Ford diesels in general. I know toyota diesel diesels, but not Fords. Anyway I just bought a 1984 F250. More torque than I will ever need ,but I am having problems with it.

It starts up fine , then after about 2 min. runs quite rough. When driving neutral throttle, somtimes all power will cut out and the thing will stall. But it starts again runs fine then stalls randamly.Sounds like a fuel starvation problem. Any first place to start? The injector pump is new.

Thanks,

Dave

 

[wgargan]

I would start with checking for air leaks and/ or possibly the mechanical lift pump.

 

[Exekiel69]

Have anyone replaced the fuel filter on this engine? how do the return lines look like? cracked/wet? How much fuel on the tank when this happens?

bBtw, Welcome.

 

[dbryan]

Thanks for the responses.

I changed the fuel filter yesterday and changed some of the rubber hoses on the driver's side, thinking that is where the problem was comming from. It makes no difference which tank I am using and how much diesel in in them.

Is the mechanical pump on the passender side engine? Easy/cheap to replace? I think there might be an electric pump somewhere too. What is the most common failure?

Thanks again.

Dave

 

[Exekiel69]

If there is an electric pump then there should not be a mech pump or it is bypassed, this engines don't need that much fuel pressure. the electric pump is the best way to go in IMO. Better replace all the return lines and caps + o-rings, just the hoses won't do to get rid of a leak if there is any. You can get the return line kit for about $25.

 

[Diesel JD]

The mechanical lift pump is a job that I HATE. The front bolt is easy but the back one is darn near impossible to reach for me. Some of these guys seem to have no problem with it. If it has an electric fuel pump someone has put it in. As teh others stated, a correct install will bypass the mechanical fuel pump. By the book it should have an oil pressure switch and a fuel pump relay from an ignition hot. You could be redneck like me and run a fused switched wire from the battery to an in cab toggle switch and run it that way. The only bad thing about that is that it may allow the pump to continue running which would allow the engine to continue to run and kill it in the event of a rollover...which also may pose a slight fire hazard. You can look at the feed lines to the mech fuel pump which is on the front bottom edge of the pass. side of the engine. It rides the cam. If the fuel lines are cut, plugged or bypassed, or if there is a block-off plate installed its a good bet that the engine has an e-pump. It is a good mod in my opinion and makes filter changes easier. Fuel and air leaks are problematic so you may well have solved your problem. If the IP is new you may still need dynamic timing if you want to get the most out of it. If it doesn't smoke too bad at idle or under load, and sounds good(no fuel knock, and not quiet like a gas engine) you have it close enough to run OK and not damage anything.