New to me M1097R1: Injector pump acts bad

LCA078 said:

Just picked up a M1097R1 from GP. The auction description it stated no batteries so nothing was operationally tested. I knew it would be a bit of a gamble but from the pics it was clean enough for me to roll the dice but now it's sitting on the trailer with a crank-no start issue. I have a couple M939s so I'm used to green iron but this is my first HMMWV. I've done lots of reading online (and no, I have not mesmerized the TM troubleshooting sections) and I'm still learning the basic mechanical operations.

Here's what I've done so far to diagnose why I think the IP is bad. Hopefully someone will prove me wrong and it'll just be a "try this and it'll start" moment.
-Used brand new group 31 batteries.
-Verified wait to start light stays on for the typical 7-10 seconds. I did not verify the glow plugs actually working since I'm in central Texas and it's in the 80's. I'm not even getting any smoke out the tailpipe so don't think it's a gp issue.
-Verified mechanical lift pump works by holding open water drain valve and cranking to see fuel come out in good volume from the filter/water separator.
-Cracked open the rear injector lines; verified no fuel at injectors during crank.
-Verified I could hear the fuel cutoff solenoid click on/off by removing wire #54A. Had 24v at with batt switch to on.
-Used a garden sprayer with a gallon of clean diesel and some cleaner to bypass the fuel supply system. This provides pressurized fuel input so I'm getting good clean fuel to injector pump (I assume the inlet screen is not clogged but that is still a possibility). Still no fuel coming out of injector lines.
-Attached clear hose to IP overflow to see the flow when cranking. Almost nothing. Practically no flow out of check valve.
-Removed overflow check valve and verified it's cleaned out by shooting brake cleaner through it. Only works one way (the correct way) so check valve works.
-Removed IP top cover and noticed governor was stuck up from gunk. Used cleaner to wash out gunk and free up governor linkage; moves freely back to "off" position after flicking it open with my finger.
-Verified I could see the fly weights rotate when cranking.
-Sucked out all old gunk, installed cover, and refilled IP with clean fuel. Verified fuel shutoff solenoid still clicks on/off.
-Cranks but still no fuel coming out of overflow. I only cranked about 5 secs as I had to leave but I really don't think it's pressurizing the IP body.

Does the no fuel out of the overflow definitively mean a bad pump? What else can I try before it's time for ripping out the IP?

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Mogman said:

What did the fuel filter look like? if it was dirty or filled with gunk then the input screen may be clogged, you should see some flow from the return even if the governor is stuck in the stop position.
You may also try feeding the IP with a mixture of diesel and MM oil.

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CallMeColt said:

I'd fill it with ATF. It is a detergent & lubricant that will help with the rubber parts. I'm fighting mine a bit still too. I just don't want to remove it & have it rebuilt.
I don't know how you can deal with Austin vs Floresville, it's two different worlds!

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LCA078 said:

I didn't mess with the fuel filter as I completely bypassed it using the garden sprayer. But yes, you're correct, I need to look at it as it is a possible issue. I ran out of time this weekend before I could get to removing the filter (and I'm still waiting on a new one to show up).

I did put a piece of clear tubing on the IP outlet so I could gauge the flow of fuel coming out. When I pressurize the IP inlet fuel line with the garden sprayer, there is a very slight seepage up through the IP without cranking. When cranking, it moves a bit more but definitely not a lot. More of a slight dribble out of the IP when cranking; kinda creeping up the clear tubing about an inch every 10 secs or so of cranking. I even removed the check valve (cleaned it until I could see through the glass bead) to verify the dribble was still just a dribble when cranking.



I took you and Mogman's advice and filled the IP up with MMO, ATF, and diesel. Even used the garden sprayer to pressurize the mixture up through the IP by verifying it was coming out of the check valve by watching the clear tubing. Again, just a dribble when cranking but it's moving through the IP.

I went ahead and did this as I'll be slammed next couple weeks so it can soak for a bit. But based on everything I read, either the inlet screen is clogged, the IP pistons are stuck, or there is still a lot of gunk inside the IP that clogging up the lines somewhere. Hopefully in a couple weeks something better will happen.

Yes, no comparison between Austin and Floresville....which is why we live outside Austin and just have an Austin address .

And, Papalote... If I remember correctly, we never stopped there since we used Skidmore as the restroom break during our trips to Port A. But I do remember the signs on 181 saying we're driving through. Good times.

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Mogman said:

If you stop and pee in Papalote they will arrest you, there are no businesses
In fact in Bee County if you are walking down or stopped on the highway the cops will check you out, not allot going on around here....

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LCA078 said:

Haha! Isn't that because of the large federal prison around there? As a kid going to the coast with the family, I remember seeing highway signs saying "Do not pick up hitchhikers". When I asked my dad about it he said it was to help prevent escapees from getting rides. After that I was always on the lookout for men walking down the side of the road wearing black and white striped clothes while carrying their steel bowling ball strapped to their ankle. Just like in the cartoons back in the day!

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