MF 135 Engine Starts Missing After Running For Awhile

[ArcherXC]

I have a 1965 MF 135 with the Continental Z145 engine. It has been giving me fits trying to figure out why it runs well for about hour then starts missing so badly I have to shut it down. It still has all the original equipment on it (Generator, original gauges, etc.). I have even moved to running ethanol free fuel to see if that would help.

I have done the following maintenance on it over the last year...

- Changed the coil
- Set timing
- Changed the regulator
- Worked on distributor
- Changed spark plugs
- New battery
- Rebuilt carb
- Had starter rebuilt
- Generator rebuilt

It doesn't seem to be heating up, at least the temp gauge shows normal range. I may need to check that gauge to make sure (by the way, what's the easiest way to check to see if temp gauge is reading correctly?).

Any ideas on why it would run great and then start missing?

 

[topbuilder]

You might pull one plug wire at a time to determine if you have a problem with one cylinder. Compression check...

 

[BertZegers]

I once had a car that would only start when cold. I could not find any thing wrong, sparks looked good. An experienced mechanic told me to replace the little capacitor on the distributor. I did and problem solved.

 

[jaxs]

I once had a car that would only start when cold. I could not find any thing wrong, sparks looked good. An experienced mechanic told me to replace the little capacitor on the distributor. I did and problem solved.

AKA condenser and those made in the last 20 years are notorious for going bad. If you change it,don't throw the old one away unless new one fixes it. If that doesn't do the trick,let us know and we can tell you how to do some tests for other possibilities.

 

[thepumpguysc]

Pulling the spark plug wire is the fastest way to narrow it down to A cylinder..
You could buy a laser temp gun off the web for 10.-15.00 & "shoot" each cylinder..
and shooting the rad. hose w/ the gun will tell you about your gauge..

 

[jaxs]

The description of how it run's "starts missing so badly I have to shut it down" doesn't sound like a dead miss nor even intermittent miss on a single cylinder. I've used many tractors,trucks and cars over the years that would foul a plug while in use. I could usually finish the chore then clean the plug before next use. When point ignition was in common use,it wasn't unusual to see someone drive a worn out car for months while it missed on one cylinder.

 

[HarryVanderpool]

Just to make sure all of your bases are covered; loosen the gas cap next time it begins missing and see if that helps.

 

[jimmyhouser]

I have a 1965 MF 135 with the Continental Z145 engine. It has been giving me fits trying to figure out why it runs well for about hour then starts missing so badly I have to shut it down. It still has all the original equipment on it (Generator, original gauges, etc.). I have even moved to running ethanol free fuel to see if that would help.

I have done the following maintenance on it over the last year...

- Changed the coil
- Set timing
- Changed the regulator
- Worked on distributor
- Changed spark plugs
- New battery
- Rebuilt carb
- Had starter rebuilt
- Generator rebuilt

It doesn't seem to be heating up, at least the temp gauge shows normal range. I may need to check that gauge to make sure (by the way, what's the easiest way to check to see if temp gauge is reading correctly?).

Any ideas on why it would run great and then start missing?

Have you performed a valve adjustment?

 

[BobG_in_VA]

OK...I'm gonna try this again....seems like this individual has put the same questions on both of the Massey Ferg forums here...I'm gonna re-paste what I asked him and also what I surmised may be his problem...this was over 2 weeks ago...got not response there...maybe here....

"Couple of questions: Are you the original owner/second/third/ owner? (I reason I asked is do you know the whole history of the engine work that has been done on the Z145? Second: Reasoning for the the first question....does the engine have the original heat shield over the carb/exhaust manifold between it and the gas tank?? If its missing the heat can cause the gas in the tank to "boil" and cause severe vapor lock in the engine....BobG in VA"

This heat shield is important....like I said before, without it, you WILL get vapor lock and cause the engine to sputter and probably die...'nuff said.