Fuel System Troubleshooting and final resolution (IT WAS THE SOCK)

98G said:

My M998 is currently dead on the side of the road, 40 miles from home. This is the M998 that's been all over the country and never had a hiccup.

I'm thinking the fuel filter is clogged. I don't know of a source of a replacement that I could get faster than late next week. (Any ideas?)

I've got a CAT spin on conversion that I was planning to use on the redtruck. I'm thinking I'll just convert the HMMWV to spin on and be able to drive it home. Any reason not to do this? (This is the whole point of my post - the rest is just rambling.)

For the last three days Janet has been driving it back and forth to work because I stole her gladiator for a trip to CO to pick up a load of useless military surplus. She has been the envy of the hospital. Yesterday the CEO wanted to drive it, so she let him drive it to lunch and it stranded him. (!!!) They towed it using the strap I keep in it, transfer case in H and transmission in N. At walking speed, maybe a mile. They (not janet) also tried to start it using ether. (Ether is absolutely contraindicated. It's quite possible that they took a trivial problem and turned it into a major one. )

My CO trip was an unmitigated disaster. I blew two separate tires on the trailer, ended up buying tires and tools and broke a jack and dropped the trailer. I was out an extra day, and went way over budget for a trip that wasnt worth doing in the first place. I got to the hospital, tired and dirty, about 9pm last night. I tried to limp the HMMWV home, and gave up about a mile into it when it acted starved for fuel and died.

I'm going after it shortly, with a standard toolset and a towbar. But I'd rather drive it than flat tow it behind the gladiator. A spin on conversion looks straightforward and very do-able on the side of the road. Comments?

Click to expand...

98G said:

My M998 is currently dead on the side of the road, 40 miles from home. This is the M998 that's been all over the country and never had a hiccup.

I'm thinking the fuel filter is clogged. I don't know of a source of a replacement that I could get faster than late next week. (Any ideas?)

I've got a CAT spin on conversion that I was planning to use on the redtruck. I'm thinking I'll just convert the HMMWV to spin on and be able to drive it home. Any reason not to do this? (This is the whole point of my post - the rest is just rambling.)

For the last three days Janet has been driving it back and forth to work because I stole her gladiator for a trip to CO to pick up a load of useless military surplus. She has been the envy of the hospital. Yesterday the CEO wanted to drive it, so she let him drive it to lunch and it stranded him. (!!!) They towed it using the strap I keep in it, transfer case in H and transmission in N. At walking speed, maybe a mile. They (not janet) also tried to start it using ether. (Ether is absolutely contraindicated. It's quite possible that they took a trivial problem and turned it into a major one. )

My CO trip was an unmitigated disaster. I blew two separate tires on the trailer, ended up buying tires and tools and broke a jack and dropped the trailer. I was out an extra day, and went way over budget for a trip that wasnt worth doing in the first place. I got to the hospital, tired and dirty, about 9pm last night. I tried to limp the HMMWV home, and gave up about a mile into it when it acted starved for fuel and died.

I'm going after it shortly, with a standard toolset and a towbar. But I'd rather drive it than flat tow it behind the gladiator. A spin on conversion looks straightforward and very do-able on the side of the road. Comments?

Click to expand...

98G said:

So today a good time was had by all.

I was unable to locate my CAT spin on conversion. That simplified choices somewhat.

I loaded the toolbox, the towbar from hell and 3/4" feet, safety chain, and took janet's Gladiator and dragged the HMMWV to the driveway.

It towed fine, like a persistent tailgater.

The fuel drain on the driver's side failed to put anything out more than a drop or two. I'm going to blow that line to ensure patency before reconnecting it.

The fuel filter looks terrible. The inner plastic tube not so bad. I think I've located the culprit lesion...

Cranking gets fuel squirting from the tank line, which should sufficiently demonstrate that the sock in the tank is ok, as is the lift pump and the line isn't occluded.

The plan at this point is to clean the filter housing, install new filter and inner plastic tube, reassemble and reassess.

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98G said:

New filter and water separator arrived today.

It didn't fix it. For about 2 miles I thought it had. Test run started out great.

Drove to the bridge. Turned around. Accelerated. Acted starved for fuel. Died. Started . Ran poorly. Drove 50 meters. Died. Repeated x3. Towed it home behind the Gladiator on the strap. (The strap has really earned its keep).

Reading the TM now... and I suspect the lift pump. Similar symptoms that my wrecker had that were resolved by a new lift pump.

Click to expand...

98G said:

My M998 is currently dead on the side of the road, 40 miles from home. This is the M998 that's been all over the country and never had a hiccup.

I'm thinking the fuel filter is clogged. I don't know of a source of a replacement that I could get faster than late next week. (Any ideas?)

I've got a CAT spin on conversion that I was planning to use on the redtruck. I'm thinking I'll just convert the HMMWV to spin on and be able to drive it home. Any reason not to do this? (This is the whole point of my post - the rest is just rambling.)

For the last three days Janet has been driving it back and forth to work because I stole her gladiator for a trip to CO to pick up a load of useless military surplus. She has been the envy of the hospital. Yesterday the CEO wanted to drive it, so she let him drive it to lunch and it stranded him. (!!!) They towed it using the strap I keep in it, transfer case in H and transmission in N. At walking speed, maybe a mile. They (not janet) also tried to start it using ether. (Ether is absolutely contraindicated. It's quite possible that they took a trivial problem and turned it into a major one. )

My CO trip was an unmitigated disaster. I blew two separate tires on the trailer, ended up buying tires and tools and broke a jack and dropped the trailer. I was out an extra day, and went way over budget for a trip that wasnt worth doing in the first place. I got to the hospital, tired and dirty, about 9pm last night. I tried to limp the HMMWV home, and gave up about a mile into it when it acted starved for fuel and died.

I'm going after it shortly, with a standard toolset and a towbar. But I'd rather drive it than flat tow it behind the gladiator. A spin on conversion looks straightforward and very do-able on the side of the road. Comments?

Click to expand...

marchplumber said:

Sounds like when i lost my injector pump on my old M1009. Symptoms are almost identical.

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98G said:

New filter and water separator arrived today.

It didn't fix it. For about 2 miles I thought it had. Test run started out great.

Drove to the bridge. Turned around. Accelerated. Acted starved for fuel. Died. Started . Ran poorly. Drove 50 meters. Died. Repeated x3. Towed it home behind the Gladiator on the strap. (The strap has really earned its keep).

Reading the TM now... and I suspect the lift pump. Similar symptoms that my wrecker had that were resolved by a new lift pump.

Click to expand...

Mogman said:

Do you have good pressure at the water drain valve while running?
Have you removed the fuel check valves?

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98G said:

Check valves coming out this afternoon.

I primed the new filter to the top of the filter housing where the fuel comes out to go towards the IP as I had doubts about the patency of the drain tube. It seemed fine while cranking. I'll be doing a more thorough assessment of that today as well.

I watched the Army's fuel system checklist video here -

I appreciate your input.

I'll report back this evening with any new developments.

Click to expand...

98G said:

New filter and water separator arrived today.

It didn't fix it. For about 2 miles I thought it had. Test run started out great.

Drove to the bridge. Turned around. Accelerated. Acted starved for fuel. Died. Started . Ran poorly. Drove 50 meters. Died. Repeated x3. Towed it home behind the Gladiator on the strap. (The strap has really earned its keep).

Reading the TM now... and I suspect the lift pump. Similar symptoms that my wrecker had that were resolved by a new lift pump.

Click to expand...

TNDRIVER said:

Do not try this... put a can of CLEAN fuel in the passenger foot well, run a hose to the mech. pump, carefully tied up so as to not get into the tire. If the truck runs good your problem is south of the pump, if not bad lift pump or injection pump. In my opinion the filter housing needs to be removed and thoroughly cleaned, "crud" accumulates in the bottom causing problems later. Removing the fuel sender and putting an eye ball in the tank might be in order if the truck runs with the "good" fuel. My 2 cents.

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98G said:

Thanks. Filter housing has already been removed and thoroughly cleaned.

@Mogman , the water drain on the driver side puts out an appropriate steady stream of fuel when opened and running. Similar to what's pictured in the Army's video.

Thing is, it runs OK at idle and while sitting still. Takes a couple minutes going down the road to show problems.

Troubleshooting continues. More info in a bit.

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Mogman said:

I would guess the lift pump is OK, I have never seen one work at idle and fail at speed.
So it sounds like there is a restriction somewhere, could be the pickup sock in the tank, the check valves,, honestly that should be one of the first thing any HMMWV owner should do, I don't remove them from trucks I sell because we live in a litigious society.
How did the filter and housing look???

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