863 power loss

SSdoxie · Jul 31, 2011

If you can run 1/2 hour before starting to loose power, 1st place to check is vent in fuel cap. Restricted lines or plugged pickup tube tend to show up in less run time. Run machine again until it starts loosing power then without shuting engine loosen the fuel cap and see primer bulb fill back up and engine recovers power.

LWG · Jul 31, 2011

I ran today without the fuel cap. The engine ran fine, but I noticed that after 5 minutes of idling, the primer bulb was sucked flat. I doubt this is correct.

Another question is whether there should be residual pressure in the fuel system when it is not running. A week ago I opened the drain on the fuel filter and a few ounces of liquid dribbled out. I think it was all fuel, but there could have been some water in it too. When I opened the drain this morning, nothing came out. I could squeeze the primer bulb and fuel easily streamed out, but I was surprised that nothing came out without squeezing the bulb.

I picked up a gallon of Lucas fuel conditioner. I added about 8 ounces, and will do so with every 10 gals of fuel. I think the problem is the fuel pickup. I hope that the fuel conditioner dissolves whatever is blocking the pickup.

SSdoxie · Jul 31, 2011

The vent in fuel has a check valve in it, intended to hold small amount of pressure (2 - 3 psi) just enough to keep fuel from draining back to tank after you shut it off.
Primer bulb still collapsing with cap off, means fuel line has restriction in it somewhere or inside of primer bulb is starting to seperate.

LWG · Jul 31, 2011

I read some posts where the fuel line was pinched under the engine. Since I just got a lot of heavy clay mud packed under the engine, I thought that might be it. But I tugged a little on the fuel line and it moved freely.

I think it has to be a clogged pick up.

What should I expect to see at the end of the pickup tube? I read elsewhere there is a 90 degree elbow which it primarily for weighing the pickup tube down. Is there any sort of filter or screen on the bottom?

This is my first diesel vehicle. I've read a lot about sludge and algae. In the last six months we've run a lot of fuel through it. I bring the fuel in 5 gal containers. The fuel and containers are very clean. What sort of problems might I have?

SSdoxie · Jul 31, 2011

The pickup tube has a 90 degree elbow at top of the tank which goes through a rubber grommet. The pickup tube itself has 2 possibilites, depending on age fo machine. There is either a rubber hose (about 18" long)clamped to fitting under the grommet, at the end of the hose is brass screen. Option 2 (newer design) there is a straight plastic tube going down from the fitting. There are 2 fittings and grommets going into the tank very close to each other, 1 is fuel pickup and other is return fuel. One other thing to check is the 90 degree fitting itself, if you have debris in your tank it can get lodged in the angle of the fitting.

SSdoxie · Jul 31, 2011

Another note about the clay packed under the engine. The fuel tank is under the clay and engine oil pan is setting on top of it. That clay can become very hard and expansion of the tank and vibration of the engine could cause it to wear a hole in oil pan of fuel tank. Best to clean it out.

LWG · Jul 31, 2011

Someone said that there is a check valve in the tank, so that if I blow compressed air in the fuel line towards the tank, it could disconnect that check valve. Is this correct?

I did clean out that clay. There is nothing under the engine.

SSdoxie · Jul 31, 2011

The check valve is there only if you have the type with rubber hose and brass fitting in the end, this has a check ball in it.

SSdoxie · Jul 31, 2011

If your 863 is "F" series, has rectangular head lights, it has the hose and check ball in it. If it is "G" series or newer, has triangle shaped headlights it probably has the straight plastic pickup tube unless someone has chnged it over to the older style hose with screen & check ball.