Hello to all,
I am new user and am new to the diesel engines. Anyways the other day I was pulling stumps with my truck when I noticed that after I revved it up (mildly) that the engine would almost die out. Now it is harder to start when cold, even if a let the glow pugs warm, and when it does start the diesel is making a loping sound. It'll rev up some, not drastically, then die down, as if it wants to shut off. The truck has 157,000 mi, and has a 4 spd. Thanks for any input

 

It sounds like the air leak problems I was working through just recently.

I suspected, and it has since been confirmed, that almost every problem with performance on these trucks or any other diesel once it lights off in the first place is directly attributable to a fuel system issue of some kind.

Water in the fuel doesn't seem too common, but air leaks or fuel leaks (which allow air in once the engine is shut down) are the most predictable gripes of all. Especially if your lines (the rubber ones) are almost twenty years old...

The plastic lines from the tank(s) also have O-rings at the connections that are made of twenty year old rubber. Go figure...

On mine I replaced the plastic lines with rubber and hose clamps because I can SEE what condition they are in. I plan on eventually running steel lines to the tanks to get rid of any flex in them.

If the fuel/water seperator has had any amount of water in it for a significant part of those twenty years, it is possible for it to rust out at the bottom (from the inside out).

Finally - the main fuel filter on top of the engine should at least be changed as often as the ownership - don't you think? There is something of interest on it - the manifold it mounts to (top piece) has an AIR BLEED... Check it and see if more bubbles than fuel come out!

Old timers have told me the best way to monitor your fuel is to install a section of clear fuel line somewhere in the system so that you can see if bubbles are running down the lines.

POINT OF ADVICE: Make sure the clear line is FUEL LINE, and not just some cheapo damned aquarium tubing!!! I found a few pieces of that on mine, and trust me, you don't want it at all...


~Wolf sends

PS: Additional warning number 1 -
If you have a mechanical fuel pump, GET RID OF IT. Bolt an electric pump to the frame just ahead of the tank selector valve and run suitable wiring. The reason is because the mech pumps can blow their diaphrams and flood the crank case with fuel - wiping out your bearings in the process.

Additional warning number 2:
NEVER use HEET or any other kind of methanol based fuel drying or water absorbing stuff in your diesel. ONLY use specific "DIESEL FUEL CONDITIONER" (this can actually help a heck of a lot, and make starting easier for one). Methanol will wreck your injectors, injector pump, and a whole world of things besides! So for krissakes save yourself a rebuild - don't go there.

 

Pulling stumps! Just how hard were you jerking? You might have cracked your pickup tube in the tank or something else that's letting it suck air.

 

I wasn't pullin reall hard. I would tension up the chain a get on it a little. Never being too hard on my truck, I like it too much. Also when yall speak of the tank, yall mean the fuel tank right. B/c I just replaced the tank about a week ago

 

Hmmm, replaced the tank, huh! Could something be sucking air around a fuel fitting? How about if you switch tanks? Does it still do it?

 

well I don't thinks so, but I will check and see. That tank is "empty" now, so i'll try to fill it up and see what happens

 

If the other tank is empty maybe that's where the air is coming from. Have you ever replaced your tank-to-tank valve on the frame? I've seen them suck air when they go bad. Mine returns fuel to the front tank when I'm running on the rear one.

 

The tank to tank valve? so is that located behind the first tank, on the frame, also what does it look like

 

The tank to tank valve or 6 port switching valve as it's called is located just in foward of the front tank. It will have 6 fuel lines coming out of it.

2 of the lines go to the rear tank, 2 go to the front tank, and finally to head off to the engine.

Each tank has a supply and return line. The fuel lines should be plastic with little clips that hold the lines to the fittings. These clips should be replaced everytime you pull them apart. They are cheap and can be picked up at just about any Ford dealer or autoparts store under the "HELP" section.

It will also have a electrical connection to it, that has the sender wires and control wires for the solenoid contained within the valve. It's about 4-5 inches long, 1-2 inches thick, 2-3 inches wide and attached inside the frame channel.