Ford F800 6.6 diesel engine fuel help

[Ridgerunner1960]

I'm a new member and I've got a 89 F800 dump truck, 6.6 Brazilian diesel, that I'm having a fuel issue with. I'm trying to eliminate the injection pump, but, before I pull it, I'd love to talk to some other guru's.

 

[Will L.]

Rule #1 on any diesel is make sure no air at the injection pump. Get clear tubing in place of the fuel line and check for bubbles.
I don’t remember the incoming pressure on those. Check your manual before proceeding.

 

[Ridgerunner1960]

Yeah, I know all about air in the fuel circuit. Truck starts and runs great, to @ 2000 rpm's. When ran higher, it starts acting like it's starving for fuel, almost like the governor is holding it back. When held around 2500-2800 rpm's, it starts missing on some cylinders. If you stop and hold the rpm's up around 1500 rpm, it will clear up. If it's held there, then, the same thing will happen, and it will die. I removed the feed and return fuel lines at the injection pump, back towards the tank and blew compressed air through the lines, to verify no blockage. Replaced the water separator filter, both feed fuel filters up by the intake manifold, all had no effect on the performance. Removed the check valve at the IP fuel return line, and the spring was not broken. It acts like the IP isn't building enough pressure, but I'm just hesitant about pulling the IP and find out there's nothing wrong with it. Thx for all the help

 

[MrMarty51]

Does this fuel system run a lift pump, and, if so, is the lift pump functioning to its fullest capacity.
It sounds like a lack of fuel to the IP to me.

 

[Ridgerunner1960]

Does this fuel system run a lift pump, and, if so, is the lift pump functioning to its fullest capacity.
It sounds like a lack of fuel to the IP to me.

 

[Ridgerunner1960]

Marty51, there isn't a separate lift pump. Only thing before the IP is the mechanical pump that bolts to the side of the IP. I've toyed with plumbing in a lift pump, down around the frame. It's just that, it wasn't built with one so; shouldn't require one. Previous to the way it's now running, it smoked a lot at lower speeds; and it was unburnt fuel smell.

 

[Will L.]

Many Diesel engines come without them but do amazingly better with them. At my current job they have hundreds of duramax trucks that didn’t come with them, but they all have them now because they learned the expensive injection pump and injector

Find what the original specs are and measure it. If the diesel fuel is getting pulled into a vacuum at the ip inlet, it will ‘boil’ and self aerate. The effect is exactly the same as sucking air in a bad fuel hose connection.

air (aeratio) can effect the whole rpm range or just specific speeds.

I don’t like to add or change things when in diagnosing problems. But this or your next ip lives longer with maximum fuel pressure, and it may (5-10% chance) help your current ip live longer now. If money is really tight and you cant really do both right now then just make sure pressure is within spec and move forward with ip.

I am a fan of verifying the rest of the systems are good like compression, timing, etc. however your description is clearly fuel starvation which may include bad ip.

If you get the chance, post some pics. That is a cool engine with comparable numbers to the 6.2/6.5 platform and many here probably never seen them. It has a unique sound to it- lopes without clacking.

 

[MrMarty51]

A short video to youtube then shared to here would be cool. I`d like to hear the sound of that engine. Even though videos and speakers dont do it justice, the rest can be imagined.

 

[Ridgerunner1960]

Thanks for your input. I've got an electric lift pump and regulator on order. I'm just not to the point of pulling the IP. I'm fully capable of doing it, but, I don't like to just throw parts at a problem. I've actually got a 6.5 diesel also in my 2000 Chevy 3500.
I'm not sure if I can upload a video on YouTube.

 

[Ridgerunner1960]