Engine cutting out at 45 MPH

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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txdodge43man
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Re: Engine cutting out at 45 MPH

Post by txdodge43man » Thu May 02, 2019 7:59 am

Rick
I understand that I'm not looking for NOS fuel pump just the best one to buy since there are many vendors out there selling them. My father and I have had issues with modern fuel and old diaphragms for year in our other MV's.

There is also Big mike's which I have heard good and bad things about his fuel pumps.
1943 MB "Puddle Jumper II"
1943 MBT
1968 m274A5
1976 m151a2 "Kermit"
1968 M416
1944 M3A4 Hand Cart

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txdodge43man
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Re: Engine cutting out at 45 MPH

Post by txdodge43man » Thu May 16, 2019 5:30 am

I fixed the issue!

After talking with many people and reading posts I decided to put a new fuel pump on and replace the fuel filter since they had been on the engine and sitting for 3 years during the restoration. I installed a new military style fuel pump with new 5/16 rubber fuel line, new inline filter and boom driving at 45 mph even got up to 50 mph yesterday. I was in aww that it was that simple, I was prepared to pull the carburetor off and mess with timing.

Thanks everyone for the suggestions of what it could have been.
1943 MB "Puddle Jumper II"
1943 MBT
1968 m274A5
1976 m151a2 "Kermit"
1968 M416
1944 M3A4 Hand Cart

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txdodge43man
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Re: Engine cutting out at 45 MPH

Post by txdodge43man » Mon Jul 08, 2019 4:31 am

Well I thought I fixed the problem.

About two Saturdays ago I was prepping the A2 for 4th of July event and on a test drive the engine started cutting out again at 45 MPH. After getting back to the house and letting everything cool down I decided to start chasing the main fuel line disconnecting ever connection and even pulled the pickup tube out of the tank. I was fed up with this issue and if I could not figure out the issue I was going to take the fuel system apart to find it.

Well once I got to the point where they metal fuel line meets rubber line going into the fuel pump I saw it. SOB how did I miss the puddle of fuel sitting on the frame rail?

So I removed the NOS rubber line which was leaking replaced it with new rubber fuel injection line using the old fittings (trying to look original) and then double checked the fuel line connections once again. I added Teflon tape to the contractions at the tank and fuel pump as I did not feel comfortable that the flared fittings were sealing properly.

That did the trick a nice long 45 to 50 mph sustained speed test drive into town and the hour drive to the 4th of July event proved it. The fuel system at 45 mph was drawing just enough air through the leaking hose or a poor sealing contention to cause the problem.

What did I learn (and I knew better) just because its NOS and pliable 1987 rubber does not last long with modern fuels.
1943 MB "Puddle Jumper II"
1943 MBT
1968 m274A5
1976 m151a2 "Kermit"
1968 M416
1944 M3A4 Hand Cart

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W. Winget
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Re: Engine cutting out at 45 MPH

Post by W. Winget » Mon Jul 08, 2019 6:58 am

After taking apart a MB Fuel pump at a show a few years back and finding granules of carbon from the rubber hose lining in the pump blocking the valve from opening and closing properly, I try to only use the more expensive Fuel Injection hose for any repairs.
Shock was when I went in and asked for 10 feet of it to have some on hand and they said it was over $120, :o so I settled for 3 feet for on-hand stock. Harder to get a good clamp seal, (and those darn Chinese screw clamps are crap) but the liner ensures it is a rather permanent fix.
V/R W Winget
Looking for 1918 Standard B 'Liberty' truck parts

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