Steelsoldiers’ BIG M1152A1 HMMWV Project!!

[M1165A1]

Just wanted to say I love my 1152A1 - I find it extremely useful as a longer bed pickup than my 1165A1. I use it to move a lot of stuff including my snowmobile in winter. My only criticism is the front seat is a little cramped for a tall guy like me.

I hope you will enjoy your own as much!

 

[steelsoldiers]

Great looking truck! I’m excited to start driving mine on a regular basis!

Just wanted to say I love my 1152A1 - I find it extremely useful as a longer bed pickup than my 1165A1. I use it to move a lot of stuff including my snowmobile in winter. My only criticism is the front seat is a little cramped for a tall guy like me.

I hope you will enjoy your own as much!

 

[Retiredwarhorses]

Lots and lots of parts have shown up since I last posted. The most recent arrivals are the left and right splash guards. I had hoped to have it in the garage so I could work on it in spite of the recent colder/rainier weather, but when I went to move it the other day, it started and I was able to back up about 15 feet before it quit and wouldn’t restart. I cranked and cranked, but no luck. I quit for the night assuming that I had probably run it out of fuel. I put five gallons in it the next day and tried to bleed the air out through the filter bleed valve. Unfortunately, the mechanical pump just isn’t strong enough to do it. I picked up a sack of plumbing parts yesterday to build a “fuel tank pressurizer.” 10-20 psi in the tank should help push the air out when cranking. Hopefully, I will have it running and into the garage tomorrow evening.

You do not need to pressureize the tank to bleed the fuel system…the lift pump, if workin, is more than sufficient to accomplish the task.

 

[steelsoldiers]

I understand. Just wanted to try it to save some wear and tear on the starter and batteries. Too bad GM didn’t use a different pump with a primer lever on it.

I ended up deleting the mechanical pump and adding an electric pump to my CUCV to make changing the fuel filter easier. It was so nice to just open the bleed valve and turn the key on.

You do not need to pressureize the tank to bleed the fuel system…the lift pump, if workin, is more than sufficient to accomplish the task.

 

[Mogman]

It could be stuck check valve/valves

 

[steelsoldiers]

It could be stuck check valve/valves

That’s a possibility. I’ll know better if it loses prime again.

 

[steelsoldiers]

Soooo, I had a little time to work on the truck this evening. The first thing I tackled was the broken fitting on top of the coolant crossover. I put some Teflon tape on the threads of the new one, tightened it down, cut the ragged end off of the hose, and attached the hose with a clamp.



That was the best part of the night. The rest was mostly frustration because it wouldn’t start. I applied about 10-15 psi of air pressure on the tank and then cranked and cranked hoping for fuel to appear at the filter bleed, but alas, it never did. After that, I disconnected the inlet line at the filter housing and cranked some more… nada. I heard a hissing coming from the front of the truck and discovered the fuel pump vent line was disconnected. I wonder if someone was getting ready to pull the pump? I crawled under a little farther to inspect the fuel tank. Turns out it is about half full of JP8, so I didn’t run it out of fuel. All of this really makes me suspect the fuel pump. Any other thoughts?

 

[TOBASH]

Soooo, I had a little time to work on the truck this evening. The first thing I tackled was the broken fitting on top of the coolant crossover. I put some Teflon tape on the threads of the new one, tightened it down, cut the ragged end off of the hose, and attached the hose with a clamp.

View attachment 908647

That was the best part of the night. The rest was mostly frustration because it wouldn’t start. I applied about 10-15 psi of air pressure on the tank and then cranked and cranked hoping for fuel to appear at the filter bleed, but alas, it never did. After that, I disconnected the inlet line at the filter housing and cranked some more… nada. I heard a hissing coming from the front of the truck and discovered the fuel pump vent line was disconnected. I wonder if someone was getting ready to pull the pump? I crawled under a little farther to inspect the fuel tank. Turns out it is about half full of JP8, so I didn’t run it out of fuel. All of this really makes me suspect the fuel pump. Any other thoughts?

Are you trying to run the truck on old fuel that has been sitting and might have water in it?

JP8 is military fuel IIRC..

 

[steelsoldiers]

Are you trying to run the truck on old fuel that has been sitting and might have water in it?

JP8 is military fuel IIRC..

My original intention was to drain the tank and start with fresh diesel, but I was hoping to be able to get the truck into the garage and out of the weather so I could work on it. I should have climbed under the truck and checked the fuel tank with a light to see how much was in it, but I didn’t. Now l have 5 gallons of fresh diesel mixed with about 1/2 a tank of JP8 or red diesel. Whatever the mixture is now, it’s not pumping. I can’t get any fuel at the fuel filter.

I may try taking the inlet line off of the pump and blowing a little air through there at 10-20 psi. That would tell me if the pickup tube is clogged. I could also get someone to listen for bubbles at the fuel filler. Another option would be to disconnect the line at the top of the tank and then remove the filler tube for inspection.

 

[steelsoldiers]

So, I took the rubber inlet line off of the pump tonight to see if I could blow some shop air through the line back into the tank. I figured that would help clear any obstructions from the fuel pickup tube strainer. Unfortunately, none of the air would go through. I followed the line from the pump all the way back to the tank to see if it had been pinched closed somewhere, but it looked fine. Then, I noticed this odd little fitting in the line near the tank and it hit me, “check valve!” See #22 in the TM photo.

Next, I am going to hook a rubber line to the pump and stick the other end in an auxiliary tank on the hood. If it will pump and run, then I should be able to narrow the issue down to the tank. If it doesn’t run, then the issue should be with the mechpump.

 

[TOBASH]

RWH constantly tells us to remove the check valves IIRC.

 

[steelsoldiers]

RWH constantly tells us to remove the check valves IIRC.

Ok thanks, Charles. I’ll try running it from a jerry can. If that works, then I’ll try pulling the check valve.

 

[serpico760]

Sand on the turbo intake side should prompt you to open up and clean.

While you’re at it, perhaps pull the 400 amp and swap to a 200amp alternator.

And sell the 400 amp to one of us fmtv guys!

 

[M1165A1]

And sell the 400 amp to one of us fmtv guys!

Yeah I still have a 400 amp in my M1152A1 that's in the picture above, I need to swap that out.

@serpico760, you will be the first to know!

 

[TNDRIVER]

Soooo, I had a little time to work on the truck this evening. The first thing I tackled was the broken fitting on top of the coolant crossover. I put some Teflon tape on the threads of the new one, tightened it down, cut the ragged end off of the hose, and attached the hose with a clamp.

View attachment 908647

That was the best part of the night. The rest was mostly frustration because it wouldn’t start. I applied about 10-15 psi of air pressure on the tank and then cranked and cranked hoping for fuel to appear at the filter bleed, but alas, it never did. After that, I disconnected the inlet line at the filter housing and cranked some more… nada. I heard a hissing coming from the front of the truck and discovered the fuel pump vent line was disconnected. I wonder if someone was getting ready to pull the pump? I crawled under a little farther to inspect the fuel tank. Turns out it is about half full of JP8, so I didn’t run it out of fuel. All of this really makes me suspect the fuel pump. Any other thoughts?

If you had air escaping from the mechanical pump on the side of the engine it's my guess that you have a ruptured diaphragm in the pump. I would disconnect the vent line as to not get fuel in the vent system as you trouble shoot he fuel system. Fuel escaping the vent fitting equals a pump replacement. Just my 2 cents. Hope you enjoy the wrench spinn'

 

[steelsoldiers]

If you had air escaping from the mechanical pump on the side of the engine it's my guess that you have a ruptured diaphragm in the pump. I would disconnect the vent line as to not get fuel in the vent system as you trouble shoot he fuel system. Fuel escaping the vent fitting equals a pump replacement. Just my 2 cents. Hope you enjoy the wrench spinn'

Thank you. Interestingly enough, the vent line was already disconnected. Not sure if they were troubleshooting the pump before it was sent to DRMO or if it was just inadvertently disconnected at some point.

 

[TOBASH]

If the diaphragm ruptures, fuel can mix with lubricating oil and cause premature engine failure. I will be replacing my pump in my M 1165 before taking it on any adventures. Maybe that’s overkill, however the pump is probably 15 years old so seems like it is preventative maintenance.

 

[steelsoldiers]

If the diaphragm ruptures, fuel can mix with lubricating oil and cause premature engine failure. I will be replacing my pump in my M 1165 before taking it on any adventures. Maybe that’s overkill, however the pump is probably 15 years old so seems like it is preventative maintenance.

Good point. If only it wasn’t such a PITA to get to LOL

 

[TNDRIVER]

Thank you. Interestingly enough, the vent line was already disconnected. Not sure if they were troubleshooting the pump before it was sent to DRMO or if it was just inadvertently disconnected at some point.

After thinking for a minute (something I don't regularly do) I believe the model truck you have has the vent system plumbed differently from the earlier trucks. The pump vent may go to the tank ......maybe. Just the same if the diaphragm is compromised fuel coming out the vent fitting is a sure sign it's pump time!
Good luck.

 

[steelsoldiers]

After thinking for a minute (something I don't regularly do) I believe the model truck you have has the vent system plumbed differently from the earlier trucks. The pump vent may go to the tank ......maybe. Just the same if the diaphragm is compromised fuel coming out the vent fitting is a sure sign it's pump time!
Good luck.

Yes, the pump vent goes all the way back to the tank. I figured that out when I tried the trick where you pressurize the fuel tank to help with priming after running it out of fuel. Air started blowing out of the disconnected vent line, but it felt like it was coming out of the pump body. Took me a minute to figure that out lol