To much fuel

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

To much fuel

Post by lawrencepk » Mon Jun 05, 2017 3:29 am

I have a 151A2 and it run great last year. When I started it this Spring it is getting to much fuel and drowning out. I checked the float and was OK and set properly. Anyone have a idea what's wrong. The carb. is a zenith 12848.


Rickf
G-Lieutenant General
G-Lieutenant General
Posts: 5909
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: To much fuel

Post by Rickf » Mon Jun 05, 2017 4:59 am

Varnish on the float needle or the needle may have degraded from alcohol in the gas. Did you have gas in it over the winter? If so it may have gone through phase separation and fed pure alcohol into the carb at the first startup. Are you running the original electric in tank fuel pump?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

Re: To much fuel

Post by lawrencepk » Mon Jun 05, 2017 5:36 am

It did sit with fuel all winter but I did start it once a month. I didn't know I had a in tank fuel pump. I have a fuel pump on the side of the block.

Rickf
G-Lieutenant General
G-Lieutenant General
Posts: 5909
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: To much fuel

Post by Rickf » Mon Jun 05, 2017 10:10 am

You "should" have an electric pump in the tank and a vacuum pump on the engine. It is common practice to take the vacuum pump off and replace it with an A2 feul pump. Kind of need to know what exactly you have and if the electric pump is working or not.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Fil Bonica
G-Captain
G-Captain
Posts: 779
Joined: Mon Sep 20, 2004 5:52 pm
Location: Cape Cod

Re: To much fuel

Post by Fil Bonica » Mon Jun 05, 2017 12:33 pm

Rick , read his description of what he has.
Its an A2.
Mechanical fuel pumpe s in order.

Fil Bonica

lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

Re: To much fuel

Post by lawrencepk » Mon Jun 05, 2017 2:05 pm

So do you think its the fuel pump or the carb?

Fil Bonica
G-Captain
G-Captain
Posts: 779
Joined: Mon Sep 20, 2004 5:52 pm
Location: Cape Cod

Re: To much fuel

Post by Fil Bonica » Mon Jun 05, 2017 4:05 pm

P
y old ł
Take the carb apart and clean especially the the fuel passage to the float.
If you can , replace the float needle valve.
Check to see if the float has developed a leak and is full of fuel.
Hopefully those items will clear the problem.

Fil Bonica

lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

Re: To much fuel

Post by lawrencepk » Mon Jun 05, 2017 4:54 pm

Thank you, I will try that and let you know how it turns out. I'm just a dumb Vietnam Vet.

Rickf
G-Lieutenant General
G-Lieutenant General
Posts: 5909
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: To much fuel

Post by Rickf » Tue Jun 06, 2017 5:38 am

We were dumb back then, not now. I saw the 12848 carb and did not see the A2. The 12848 is an A1 carb so I was thinking you had an A1. The float may be brass but not likely but it is very possible that the float level is set wrong. It is very critical on these carbs. 9/32 for the float height and 3/8 on the drop.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

svramselaar
G-First Lieutenant
G-First Lieutenant
Posts: 608
Joined: Sun Sep 28, 2003 1:32 am
Location: spakenburg holland

Re: To much fuel

Post by svramselaar » Tue Jun 06, 2017 11:52 pm

hi

it is possible the membrane from the acceleration pump is leaking
if it has a damage the engine sucks extra petrol trow it


george
1976 ? M 151 A2 AMG MUTT lost in acsedent
1978 M 416 A1 ( parkhurst ) trailer
1970 m151 A2 FORD BUDD tub
1957 Volvo sugga radio truck
M 274 mule HOME MADE MULE

lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

Re: To much fuel

Post by lawrencepk » Sat Jun 10, 2017 3:17 pm

Rickf wrote:We were dumb back then, not now. I saw the 12848 carb and did not see the A2. The 12848 is an A1 carb so I was thinking you had an A1. The float may be brass but not likely but it is very possible that the float level is set wrong. It is very critical on these carbs. 9/32 for the float height and 3/8 on the drop.

I rebuilt the carb but it didn't fix the problem, now what?

Rickf
G-Lieutenant General
G-Lieutenant General
Posts: 5909
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: To much fuel

Post by Rickf » Sat Jun 10, 2017 3:23 pm

Did you replace the needle and seat and set the float level at the 9/32 and 3/8 drop? If so then you need to check your fuel pressure. Not likely the pump has increased in pressure but stranger things have happened. Should be around 3 1/2 lbs.
When you rebuilt the carb did you check to make sure the power valve was opening and closing cleanly? If it is sticking open it will be passing extra gas the whole time it is running.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

Re: To much fuel

Post by lawrencepk » Sun Jun 11, 2017 2:49 am

Sorry- what's the power valve?

Rickf
G-Lieutenant General
G-Lieutenant General
Posts: 5909
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: To much fuel

Post by Rickf » Sun Jun 11, 2017 6:41 am

If you take the cover off of the accelerator pump first you have the spring and then the diaphragm, then inside directly in the middle you will see a brass valve, this is the power valve. In the center of that is a spring loaded plunger that is depressed when the accelerator pump fully unloads and stays there, which is what happens at wide open throttle. It holds that little plunger open and allows more gas to flow in the emulsion tube. You can actually feel this happen if you are at around 45-50 MPH and mash the gas. You will feel the initial push and then it will pick up a little more as that valve is opened. Now, if that valve is not closing all the way you could be getting more gas than you should, this would more than likely show up at above idle speeds. If you are having this problem at idle then I still suspect a float issue or a leaky needle and seat, or too high fuel pressure. Did the carb have a brass float or composite float?

That valve will unscrew out of there for inspection.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

lawrencepk
G-Corporal
G-Corporal
Posts: 27
Joined: Fri Jun 02, 2017 3:51 pm
Location: Fort Recovery, ohio

Re: To much fuel

Post by lawrencepk » Sun Jun 11, 2017 1:55 pm

Ok I see what you call the power valve and most of that was part of the rebuild. I have a composite float. Does anyone just sell the float? Yes my problem is at idle.


Post Reply

Return to “M151's Technical Knowledge Base”

Who is online

Users browsing this forum: No registered users and 36 guests