Fuel pump dead!

[nlines]

Has anyone changed their fuel pump lately? I can barely reach it much less remove the inlet and outlet hoses.

[john8662]

Yeah. It's not too bad really.

There is one hard line that has a nut going out of the pump and one soft line which is the inlet.

Remove the lines (for the hard line I recommend a line wrench) then the 4 bolts holding the cover and the plate to the block. The plate has to come off the majority of the time because there is a pushrod behind it that comes down and doesn't easily push back up from within the hole once its come down.

Once you have the plate off, you'll see the rod. Pull it out, coat it with some grease, put it back in it's bore and it'll stay up due to the grease.

Prepare your plate and pump for reassembly.

It's about a 2 hour job between removal and gasket scraping cleaning prior to going back on. And you're going to get some Diesel on ya, no way around it.

J

[arveetek]

Here are some tips that I wrote up way back in 2003:


Hard starting can often be attributed to a failing fuel lift pump. This mechanical pump is mounted down on the lower, front passenger side of the engine block, in the same place as on the gasser blocks.

I have changed several pumps, and through trial and error, have come up with the following tips for changing this pump out. When you remove the pump, you allow air into the system, and if you don't follow these steps, you can end up with an air-locked diesel engine, which can be rather frustrating to start.

These steps apply to 84 and up 6.2L diesel equipped trucks with the Model 80 square fuel filter mounted on the firewall. For 82-83 trucks with the round, spin-on style filters, read the note at the bottom.

First, drain the fuel filter. On the very bottom right side of the fuel filter assy. is a little plastic valve. Right under this valve should be a barbed hose fitting pointing straight down....it will be hard to see, you can feel it though. There might already be a length of hose attached to this fitting. If not, get a length of hose to help drain the fuel away from the truck and into a pan or something. You don't have to, but it will make a much cleaner job.

On top of the fuel filter assy. is another small plastic valve directly above a smaller barbed fuel fitting pointing straight out on the left side. This is the air bleed valve. Open this valve, and then open the drain valve on the bottom. This will let the fuel drain out of the filter, down the hose, and into a pan. This will prevent fuel from spilling all over you when you remove the pump.

After the fuel has drained, start removing the pump by disconnecting the fuel lines. The suction side will have a rubber hose and clamp, the pressure side will have a steel line screwed into the pump. Use a 9/16" line wrench if you can to avoid stripping this fitting. When you remove the suction hose, it may continue to dribble fuel out. If so, shove a 3/8" bolt into that hose to stop it up.

Next, remove the two mounting bolts holding the pump on. IIRC, you need a 1/2" socket for this. The bolt on the back side of the pump is hard to get to. You can try getting to it from the top side of the motor or from the bottom. I think the top side is just a bit easier.

Remove the pump.

Now remove the plunger rod cover by removing the two remaining bolts at the bottom. IIRC, these require a 7/16" socket. You have to remove this plate in order to remove the plunger rod. When you removed the pump, the rod probably fell down. Now you can't get the rod to stay up in place. (This rod rides against the camshaft, which in turn rides against the pump plunger.) Once you remove the cover, slide the rod out. Cover it with thick grease, and shove it back up in the hole. The grease will help hold it in place. There is a chance that the motor shut off in a place where the camshaft lobe is holding the rod out in the extended position. If this happened, it will be next to impossible to install the pump. I suggest you rotate the engine by putting a large socket on one of the front pulley bolts. You can tell when the rod is retracted all the way because it goes way up in there out of the way.

Clean up the surfaces on the rod cover and the engine block. I like to use Ultra Copper silicone sealant on these parts. Reinstall the cover.

The pump should come with a gasket. I typically install the gasket along with Indian Head gasket Shellac.

Install the pump.

Reconnect the fuel lines.

Now you have to bleed the fuel system. First, if you haven't recently replaced the fuel filter, go ahead and install a new one. Just undo the clasps and pull straight out on the filter. Put a little oil on the o-rings of the new one when you go to install it. The new just pushes back on.

Close the drain valve on the bottom of the fuel filter assy, but leave the air valve on top open. Next, disconnect the fuel cut-off solenoid on the injection pump. This is the pink wire right on top of the pump itself. We want to avoid pumping any air into the injection lines when we start cranking the motor, and by removing this wire, the air can't get into them.

To save battery power and the glow plugs, disconnect all 8 wires going to the glow plugs. (that is if you have an automatic glow system...if yours is manual, then just don't glow!)

If you can, install a piece of clear tubing over the small barb on the top left of the fuel filter assy. I usually run this clear hose into a container sitting on the cowl of the vehicle so I can see it from the driver's seat.

Start cranking the motor over. We're not trying to start it, we're just priming the system. What you're doing is pumping fuel from the tank, into the pump, up to the filter, and back through the return lines. Since the injection pump is disconnected, it won't get any air in it and get air-locked.

Only crank the motor for no more than 30 seconds. I have personally burned up a starter by cranking too long. Let the starter cool for 2 minutes before cranking again.

When you see clean diesel fuel coming out the hose at the top of the fuel filter, shut the air bleed valve off, disconnect the clear hose, reconnect the pink wire to the injection pump, reconnect the glow plugs, and start it up. I guarantee it start up on the first try with this technique (as long as the injection lines didn't have air in them to start with).

I know this seems like a lot of steps, but you should be able to get this all done in under 2 hours. I can do it now in under one hour. Using these steps makes it very easy to change the pump and bleed the fuel system.

BTW...you can use these same steps to change the fuel filter. Just skip the part about changing the pump!

Good luck!

NOTE: Since the 82-83 trucks use spin-on fuel filters with no air-bleed valves, the only way to bleed the system is to fill the filters up with clean diesel fuel, install them, and then crank the engine over for a while with the pink wire disconnected from the injection pump. It's hard to know when the air is purged, but I have found that two 30 second cranking sessions should be plenty. Then reconnect the pink wire, and start the engine. Keep the motor revved up a bit until it seems to be running smoothly


Hope this helps

Casey