Engine sputters when hot. NOT ignition coil this time???

[vinhvinny]

After a few months of good running engine, now it starts having problems: when I press the gas pedal my Mutt hesitates, sputters only after it gets hot (after about 10 minutes of running.)


I figured this was a classic case bad ignition coil, so I ordered a new coil (Taiwanese chrome New Star) but it behaves just the same! exactly at about 10 mins running, the engine can't rev up, sputters. PLEASE SEE VIDEO: https://youtu.be/28p0JHwYs-o






Please also note that, even when it is hot and behaves like so, I can restart it very easily--first try--after a quick shut down.


And I went further to test to see if it is the coil: while the engine is hot and sputter like that, with the help of my wife, we opened up the distributor and put the old cool USGI coil in in LESS THAN 3 minutes. Fire up, It still sputters.


Furthermore, after cooling down the chrome New Star coil real good, I ran the USGI coil til the engine sputters again and swap it: same problem!


I also inspected that the vacuum line to cool the coil down works.


So I know for sure something else does not work properly when it gets hot. Not the coil.
Again, when the truck starts from cold it runs like a charm with no issues but after about 10 mins or so here comes the hiccup
Could it be the new solid state electronic ignition kit that I just replaced? (Taiwanese New Star also.)


The New spark plugs still look good:

The accelerated pump diaphragm appears to be good, and put back as in the picture below:





Engine temperature at 170 measured by coolant in radiator.


Fuel pump and flow is visually fine judging by the clear filter--alway in full supply.


Can y'all help me figure out what could possible cause that sputtering when engine is hot?


I've got a cool M60 machine gun mounted on it, now it can't run.


I've done following repairs/replacement:


. Carb rebuilt
. Correct gas tank cap/gas tank cleaned.
. New Solid State Electronic Ignition Kit by Taiwanese New Star here:

.Timing is corrected, at 6* BTDC


Thank you so much.


Gratefully Yours,


vinny
VIDEO:
https://youtu.be/28p0JHwYs-o

 

[nattieleather]

Check your fuel pump. Not sure if you have a A2 fuel pump or not. It might be that when the engine warms up the diaphragm in the fuel pump loosens up and it can't deliver the fuel properly. Also try putting a 45 degree elbow on the fuel inlet to the carb. That will move the fuel filter slightly and stop it from getting hot and vapor locking. I've had that problem on my A1 and my A2 and those were the fixes for mine.

 

[USMC 00-08]

I have a similar problem with my M135 when it is hot. Not as noticeable in the cooler weather, but more so during the summer months. Really interested in seeing what solves this for you.

 

[vinhvinny]

normally, this is caused by bad ignition coil, after running for awhile , much current and heat, it will misfires or sputter.

as I suspected: the swiss ignition control module. I ve got a new one for warranty. It runs normal now.

for you, look seriously into distributor system (coil and module) then spark plug and wires last.

good luck

nattieleather, as you can see it the video, gas spray pretty good.

 

[m38inmaine]

Spark plug would tell me it's running rich.

 

[silverstate55]

Try to route your fuel lines away from anything hot, as best as you can, and do NOT run any fuel with ethanol in it. You might be experiencing a form of vapor lock (common on older engines with ethanol added to fuel).

 

[nattieleather]

So did a new coil fix the problem or are you still having an issue?

 

[vinhvinny]

this time is NOT the coil, it is the Swiss control ignition model this time. What i said was that it is a classic case of failed coil.

This right here:

it is only a new production Taiwanese made though, called New Star. but i bought from an authorized dealer so S&S Truck Parts sent me a new unit in two days. No question asked. I like that a lot.
Don't buy on ebay. can be cheaper but they are not vetted by S&S.

but yes, I am going insulate my fuel line.

 

[dmetalmiki]

I was having that problem, and cured it with a replacement distributor, ignition, and coil leads. Rather glad I just swapped the mutt (M151A1) for a 2 1/2 ton deuce (A2) with winch. It needed a Lot of work and rectification though, but now I am glad I did the swap. As there were also more problems to sort out on that Mutt. Axle noises, and some manifold faults. (leaks).

 

[74M35A2]

New parts don't mean good parts. Also, if this engine has a valve lash adjustment, I would go through that. Valve lash is clearance necessary for when an engine heats up, and still has clearance to not hold valves open.

 

[Amer-team]

Have replaced both coil and pick up module. Still same problem. Have not checked fuel
Pump other than that it is pumping. Anyone have a problem with clogged pickup in tank?

 

[CMPPhil]

Hi

If you lived up north my first question would be is the gas fresh? I've learned that if any of my trucks runs rough in the spring is don't fix anything until they are running fresh fuel.

Back to your problem please keep us posted on what makes the problem go away.

Cheers Phil

 

[Badojeep]

I had the same problem, there is a wire inside the dist housing that runs to the connection port, it fails over time, acts just like coil cutting out. runs fine cold acts up hot.

 

[Badojeep]

lol this post is 2 years old,hope he got it running

 

[m1161]

Solid State Electronic Ignition Kit by Taiwanese New Star

Where can I find that solid kit for sale?
thanks, larry

 

[lpcoating]

Vin Zike has some for sale on the G838 site.

 

[lpcoating]

Electronic Ignition Kits - G838 Owner's Club

g838.org

 

[Muttmutt]

I had one at the beach that did that and it was getting fuel in the air cleaner and filled it up to where it couldn’t get air to run.

 

[lpcoating]

I had one at the beach that did that and it was getting fuel in the air cleaner and filled it up to where it couldn’t get air to run.

Sounds like your fuel breather line valve isn't working. A friend had the same issue. We were on a road trip, just filled up with gas and the trucks sat in the sun for about 30 min. His fuel line breather wasn't working properly and it filled the air cleaner with gas.