Engine sputters when hot. NOT ignition coil this time! Help

[Venito]

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 solid state electronic ignition kit that I replaced? (Taiwanese New Star also.)

The spark plugs 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:

. New spark plugs (autolite 2245?)
.Timing is corrected, at 6* BTDC

Thank you so much.

Gratefully Yours,

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

[Tom]

Does closing the choke make any difference?

[rickf]

The plugs are looking very sooty, like it is running too rich. This will not cause that problem, just an observation. Almost like the plugs are one or two steps too cold. It is sounding like the ignition module, it is definitely heat related and you have done a good job to eliminate the coil. I have a very low confidence in anything from New Star anymore, everything I see from there is crap. Does anyone out there know where we can get the GOOD Swiss controls ignitions?

[Venito]

No, Tom, adjusting the choke does not help with this issue.

Is the ignition module known to cause misfiring like this when the engine gets hot?

So what are the common symptoms of a bad Swiss control ignition module?

The only good thing about New Start is that they have 100K M/1 yr warranty on their products if bought from an authorized distributor, which I did. They are sending me a new one today.

Since you said about soot, running rich and cold. I have a pix of all four:



These are autolite 2245.

From what I understand is that there only ONE adjustment can be done on the carb that is the idle mixture, which controls the fuel to keep the engine running when throttle butterfly is closed. However, that seems to have no effect whichever way I turn it , even though I did clear the circuit when I rebuilt it.

I think it runs rich too, it idles very loud and powerful, Is there anyway I can adjust the amount of fuel coming out of main tube at the venturi?


Well, there is another adjustment I forgot to mentioned was the screw outside to adjust the opening of the throttle butterfly.

[rickf]

Set your idle at somewhere around 550 rpm, by ear, it does not have to be perfect. Just a nice low idle. Then turn the idle mixture screw in until it starts to slow down and stumble, with a 13660 carb this could take quite a few turns, the threads are very fine on the screw. Then turn it back out until it idles smooth and go further until it starts to stumble again. Then go back halfway between these two settings. This is the best idle setting. IF you have any issues with it stumbling or have a flat spot at higher rpms than turn the idle mixture screw out two turns at a time trying it for a while at each setting. It should run good withing 6 - 8 turns at the most. I will not say the ignition module is "Known" to cause problems like this but this is a heat related issue and you have eliminated the coil so the only thing left is the module. Heat can cause electronics to cut out or short out.

[Venito]

Sir, I report to you, sir.

It was a success. It was indeed the Swiss module.

New Star in fact honored their 100KM warranty and promptly sent me a new one in two days.

However, I am currently running on both New Star module and coil. after about 40 min running it has hiccup and misfiring a little.

Originally, the mutt had backfire out of exhaust pipe after shut down. I advanced the timing--I don't know how many degrees--but about half an inch. That seems to help.

But this time while trying to figure thing out, I put it back at exact 6* BTDC. I now might have to advance it see if that helps.

All the while I have little clue what advanced timing can do to help with misfiring or backfiring. I only know that it give the Jeep more power.

[rickf]

Advancing the timing a few degrees will not hurt anything and as long as it runs good that way then leave it there. It has been my experience that the M-151 runs best with the timing set right on the mark at 6 degrees. It you moved the distributor a 1/2 inch then you are probably 20 degrees advanced and are taking chances of putting holes in pistons. If it is running good there then I am thinking the mechanical advance is not working or it would be pinging severely. It should also be kicking back when trying to start. Something just does not sound right here.

[Fil Bonica]

Vin , if. I were you I would try and find a competent local mechanic who could properly diagnose anx repair this engine once and for all
It seems like you are chasing your tail with one thing or another and missing. the fun of driving around..
Its awfully difficult to analyze things via remote control.
Just too many things are lost in translation
Good Luck finding a mechanic

Fil Bonica

[Mr. Recovery]

The plugs are looking very sooty, like it is running too rich. This will not cause that problem, just an observation. Almost like the plugs are one or two steps too cold. It is sounding like the ignition module, it is definitely heat related and you have done a good job to eliminate the coil. I have a very low confidence in anything from New Star anymore, everything I see from there is crap. Does anyone out there know where we can get the GOOD Swiss controls ignitions?

http://www.ebay.com/itm/191803786211?_t ... EBIDX%3AIT

[Fil Bonica]

Dan, saw those posted and was going to ask if they were NOS.
Not interested in repro.

Fil Bonica

[rickf]

Note the country of origin. Taiwan.

[raymond]

Note the country of origin. Taiwan.

Is that where the chrome coils come from I thought they were coming from China.

[rickf]

I am going to guess it is Chinese origin and Taiwanese export, It is all coming from NewStar anymore. I guess once production stopped the real manufacturers did not see any profit in continuing to make parts after the contracts ran out. The last contract for carburetors was actually filled overseas but the quality of them was equal to the originals. Now there is no oversight so cheaper is better. If things do not improve I will be selling mine due to the lack of usable available parts. I have NOS coils and a couple distributors with the original electronics in them but I want to drive it and not have to worry that if it dies then I have nothing to replace it with. I would be much better selling it before it no longer runs and I have no parts. I am curious how the M-38 guys are doing it? they are in the same boat as us which basically means what we need they need so the resources are dwindling that much faster, It is not just M-151 guys looking for coils and modules. Add in M-38's, M-715's M-38A1's, M-37's. That's a LOT of needed coils and modules and/or points. None of which are being made anymore.

[Venito]

New star products are made in Taiwan.

That on ebay is indeed New Star:pich black shiny resin. No number on back.

But they stand by their 100,000mile or 1 yr warranty. I called wed, got new one delivered to my door on Fri. Can't complain.

Rick, not 1/2 inch of moving the distributor.
But 1/2 in from pointer of 6 btdc. If the disc is 360 degrees for the entire circumference then i advance it about 2-3 degrees then, which is now 3• btdc. I finds it working better that way. Also the centrifugal advance seems ok: increased rpm makes it become advanced.

Fil, one good mech i can afford, a friend, is always busy. Others are either too expensive or "i ve never worked on carburetor engine!"

I got it running good for months. And now. Again.

Life is a learning process. I ve learned a lot so far.

Vin.

[rickf]

Got it, but if the notch on the pulley is ahead of the timing mark on the cover then it is advanced about 3 Degrees hence 9 degrees. That is not too much as long as it is not pinging. The alcohol in the gas nowadays will help with that. I tend to believe it is advanced more than retarded if it is running with more power. as long as it is running good then that is what counts.