Another problem with M135??

checked each plug for spark and they all have spark. We cannot continue to keep tearing things apart, seeming to find and fix the problem, then it starts all over again. There has to be something causing this.
It has been suggested we buy a rebuilt carb? But I am reluctant to cough up The $400 on a guess? If I knew that would fix it, sure no problem. But to guess??
I sure could use some help, I'd hire a mechanic if I knew one.
We only have this truck to benefit veterans. We have missed Memorial Day due to it being down, and here comes the 4th of July.

Out us all reading about your issues. You are the only one with hands on the truck. I am in no way trying to offend or belittle.

You started with a fuel issue. Then it was ignition. Exhaust issues too, but they should not have any bearing on how it actually runs. Now it is an unknown loss of power while driving. I think you have had your hands on the issue. There is only fuel, air and spark needed to make it run. All 3 have been covered.

My suggestion is follow the troubleshooting in the manual from the beginning and do every single test to completion it says to do in the order it says do it. Probably starting with a full tank of known good fuel and fully charged and load tested batteries.

The only other thing I can offer is fuel filters do sometimes have enough sediment in them to flow fuel until 10-15 minutes into running and then sometimes that sediment will block the filter. The in tank “sock” sometimes does that as well. Ignition coils also will test fine and then once surrounded by hot components start to fall off until the engine barely runs. My M35 Gasser had 2 coils do that to me over the years. Sitting on the side of a 100° road for an hour isn’t fun just to have it fire right up and run perfect again for about 10 minutes and then repeat.

Sir, I appreciate your comments. I am aware of what makes an old gasser run. But this is what makes this all so perplexing. I have gone thru that trouble shooting part of the manual, not completely, but a lot of it. What gets me is it seems fixed, then does it again? I am about to try the previous coil, since that was not initially the problem.
Also, with all this cheap gas I wonder if that could be an issue, or vapor lock. With ethenol now in the gas, I am told that alcohol vaporizes at a lower temp, and since there could be 10% in the gas, well that could be a problem? But it ran fine for many years on the same stuff?
Thanks again for your input.

Did we get the compression tested? Let's get those readings.



It's great exercise on page 188 for compression and vacuum tests. Following the steps in 9-8024, you remove all the spark plugs, hook up the gauge, slide off the fender, climb up in the cab, pull the starter, climb out of the cab, climb under the hood, check gauge/ record reading.....then do that 5 more times.

Really surprised that the variance between cylinders can be 30 to 40 psi...... Pg. 188, ...111 Compression test #5. These are a few readings off a donor motor.



The other funky item on the previous page in 9-8024 is the suggestion to torque head bolts before you adjust the valves. Pg. 186,.....110 Valve Clearance Adjustment c.

You asked about vacuum and that test can be done right after we know the compression readings again. Get er' done.

We could not get to check the compression or vacuum today. There was a "mechanic" (?) my son had coming over this afternoon, but he backed out. And I had other things I decided needed done.
But concerning vacuum let me ask this? There is a line from the intake manifold to the valve cover, with a valve on it. What if that valve were stuck open? Would that be the same as a manifold gasket leak?? Sucking air??
Just grasping at straws. I am going to try and check that compression tomorrow for sure.

Brad said:

We could not get to check the compression or vacuum today. There was a "mechanic" (?) my son had coming over this afternoon, but he backed out. And I had other things I decided needed done.
But concerning vacuum let me ask this? There is a line from the intake manifold to the valve cover, with a valve on it. What if that valve were stuck open? Would that be the same as a manifold gasket leak?? Sucking air??
Just grasping at straws. I am going to try and check that compression tomorrow for sure.

Click to expand...

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You could buy a can of either... Running the motor, spray the either all around the carb and you should see an increase in speed if you find an intake leak. Cheap way to check. You just hone in on the space where you spray...

Mulaney,
Thanks for that suggestion. I did try that a week or so agao with no difference detected. BUT, what we had was called "starting fluid" it did not say either. I told my son to pick it up on his way home from work and that is what he bought.
Is there a difference? It smells like either?
Here is another question. We are out of adjustment on the belt for the generator. It is looser than it should be, ut the amp gauge still shows it is charging. I am planning on replacing the belt once we get this thing running right. But, could that actually be a problem with the way it runs? I find it hard to believe and my experience with other old vehicles tells me not. But this is a different animal?
Thanks again to all

Brad said:

Mulaney,
Thanks for that suggestion. I did try that a week or so agao with no difference detected. BUT, what we had was called "starting fluid" it did not say either. I told my son to pick it up on his way home from work and that is what he bought.
Is there a difference? It smells like either?
Here is another question. We are out of adjustment on the belt for the generator. It is looser than it should be, ut the amp gauge still shows it is charging. I am planning on replacing the belt once we get this thing running right. But, could that actually be a problem with the way it runs? I find it hard to believe and my experience with other old vehicles tells me not. But this is a different animal?
Thanks again to all

Click to expand...

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Yessir. Starting Fluid . Either - Both smell about the same.
So, you have already sprayed all around the carb - with no change at all?

I really don't think that you will solve it with a new belt on the generator.
I mean it sure won't hurt to change it. If you have a fully charged battery, you should be able to drive the truck for several hours without the generator turning.