engine stalls after running good for 45ish minutes

labjack

Member
Ok, I know some of you folks know these things offhand so I'll run it by you. Have a 63 4000(4cyl) gasser. She starts up and runs fine for 45 minutes give or take a little and then stalls all of sudden and dies. It's happened last two times I've used it, about a month apart. First time I let it sit about an hour and came back and it started right up and I drove it to the shed w/o incident. Today I let it set for just 10 mins. or so and it started up, took it back to the shed w/o incident again. Didn't have the stuff to check for spark or fuel flow with me in the field. Guess I'm gonna have to take it with me next time. Does it sound like anything specific? or just gonna have to trou
ble shoot a little. btw the engine wasn't very hot when this happens, just maybe a 1/4" into the green on the gauge.
Sorry for the long post and thanks in advance for any advice.

Mark
 
You are going to get plenty of suggestions on this from the members. I would check out the
ignition switch first, since that is probably the easier. Once started, jumper around the ignition
switch and see if the problem persists.
 
Besides the ignition switch, as Tim already suggested, there are two things that can cause the engine to die after runing fine for an extended time.

1. The gas cap vent may be clogged. To test this simply open the cap slowly after the engine has died. You may be able to hear the "woosh" as the vacuum is relieved, or maybe not, but since it takes 10 minutes fto be able to start again, wait about 30 seconds after opening the gas cap to see if it will start again. If so, that means that the fuel cap vent is clogged and opening it allowed the carb to refill with gas.

2. The coil may be going bad. The first signs of a coil going bad is usually cutting off when warmed up. Only way to test this is to either have a spare coil to insert into the circuit when the problem happens or pull a spark plug wire and hold it near a good clean ground while cranking the starter to see if you have a good strong blue/white spark.

I recommend testing the gas cap for a clogged vent first.
 

Ok, looks like I have a few things to try next time I use it. Thanks for all the suggestions so far. Not sure when I will use it again for that long of a time but I will keep you updated if I figure something out(or not).

Mark
 
The fact that it will run for 45 minute, die, and be restarted 10 minutes later sounds like a fuel problem. Pull the drain plug on the carburetor and see if the gas continues to flow for 2-3 minutes. I don't know of any quicker way to identify if fuel is the cause.
 

I agree with young fella Old that it is most likely the coil. However, a jumper wire with alligator clips is a whole lot cheaper than a coil, so try jumping, (as opposed to jumpering), around the ignition switch before going out and getting a new coil.
 
Don't overlook a clogged vent hole in your fuel tank cap.....otherwise my hat is in the ring for a bad coil. I know from experience heat kills a bad coil but
never tore one apart to see why.....permability degradation, lamination to lamination short, wire varnish cracked and falling off a wire causing a turn to
turn short which will kill one in a heartbeat, cracked insulator but that would show up better when cold and damp.????????????
 
The fact that it will run for 45 minute, die, and be restarted 10 minutes later sounds like a fuel problem. Pull the drain plug on the carburetor and see if the gas continues to flow for 2-3 minutes. I don't know of any quicker way to identify if fuel is the cause.

labjack,

My 971 did the same thing many moons ago and I finally found the exhaust was heating the tank/fuel line enough to cause "boiling". When this occurred, it would puny out, but be fine after sitting a bit. I was able to see air bubbles in the sediment bowl.

I added a small heat shield off of the front exhaust header bolt and it hasn't been a problem again for years.

Chris
 
(quoted from post at 09:39:12 03/21/19) Don't overlook a clogged vent hole in your fuel tank cap.....otherwise my hat is in the ring for a bad coil. I know from experience heat kills a bad coil but
never tore one apart to see why.....permability degradation, lamination to lamination short, wire varnish cracked and falling off a wire causing a turn to
turn short which will kill one in a heartbeat, cracked insulator but that would show up better when cold and damp.????????????

The wire in the windings expand and contract as they heat up and cool down. Over time the laminated insulation on the individual windings develops minuscule cracks which eventually open up enough when the windings are hot that some of them begin to short from one winding to the next. Eventually those individual shorts within the windings cause enough loss of voltage when hot for the coil to be unable to provide enough voltage for a strong enough spark so the engine dies. Wait for the coil to cool off and the windings shrink back down and the cracks in the insulation close up enough that it can again provide a strong enough spark for the engine to run. As the coil ages little bits of the edges of the insulation next to those tiny cracks flake away so that the cracks don't close up as well when it cools off, and over time the temperature at which problems occur gets lower and lower until eventually there are enough micro shorts between windings that it won't even provide a strong enough spark to run when cold.
 
Ok, so where exactly do I hook up the bypass wire to rule out(or in) the ignition switch. Sounds like an easy thing to try so might as well do that first.
That said, earlier this winter I changed my fuel shutoff from lever to screw type and replaced the fuel line along with it. So, I'm figuring the line may need some shielding. Looks like it will be hard to work in that tight space though. Any suggestions on that?

Mark
 
(quoted from post at 12:52:21 03/21/19) Ok, so where exactly do I hook up the bypass wire to rule out(or in) the ignition switch. Sounds like an easy thing to try so might as well do that first.
That said, earlier this winter I changed my fuel shutoff from lever to screw type and replaced the fuel line along with it. So, I'm figuring the line may need some shielding. Looks like it will be hard to work in that tight space though. Any suggestions on that?

Mark
or coil jumper, just connect directly to battery. As to the heat shield, I would ask, "if it has been fine for X number of years & you haven't changed anything, why would anyone expect a heat problem now?".
 
(quoted from post at 12:52:21 03/21/19)
That said, earlier this winter I changed my fuel shutoff from lever to screw type and replaced the fuel line along with it. So, I'm figuring the line may need some shielding.

JMOR - I just based my suggestion on a very similar description to a problem I had experienced. Based on your premise, if you don't change anything, these tractors should run forever (and sometimes they nearly do) :)

Chris
 
(reply to post at 10:39:0
8 03/21/19)
As you can see in the quote I did replumb the fuel line earlier this winter so it may be situated a little differently than it was. It's steel about half way down and the rest is rubber(neoprene?) or whatever it is. So it is possible that is the issue.
 
I thought I saw the word FILTER in one of your posts. ?
If so, an inline filter can cause problems on a gravity flow system like on these tractors.
Maybe something else to check.
HTH
Keith
 
(quoted from post at 21:53:45 03/21/19)
(reply to post at 10:39:0
8 03/21/19)
As you can see in the quote I did replumb the fuel line earlier this winter so it may be situated a little differently than it was. It's steel about half way down and the rest is rubber(neoprene?) or whatever it is. So it is possible that is the issue.
y apologies. I need to read more carefully. Yes, the fuel line between block and exhaust is bad location in my opinion, but many have ran for over 60 years like that, so if carefully positioned? But of course gasoline formulation has changed over those years.
 

So, used the tractor again today and as expected after 30-45mins it cut out and died rather abruptly. Checked the spark right away and it seemed fine. Took the carb bowl drain off and little to no gas. Then I took the sediment bowl off and there was good flow from the tank. So not getting flow to the carb. There were some fines in the bowl last time I used it and I cleaned it out. They were there again, so I'm guessing I have rust in the tank. Had this problem about 10-15yrs. ago and had the tank relined. It was good till recently. I don't know why letting it set 10 or more minutes allows it to run again. Any ideas?Thinking maybe new tank this time. Are the new tanks ok? I know some of the new parts are not the quality of oem. I think it cost about as much to reline as a new one. Carb will need to be cleaned to I suppose.
 
Yes, I removed the carb drain plug and there was barely any flow at all, so that's when I removed the sediment bowl and there was good flow from the tank. I don't know why letting it set for a while would allow it to run ok again if it's getting rust(sediment) in the system. Also checked fuel tank cap, it was ok.
 
(quoted from post at 17:51:07 03/28/19) Yes, I removed the carb drain plug and there was barely any flow at all, so that's when I removed the sediment bowl and there was good flow from the tank. I don't know why letting it set for a while would allow it to run ok again if it's getting rust(sediment) in the system. Also checked fuel tank cap, it was ok.

Well, that would tell me that I may have another screen or some other blockage after the bowl.
 
Yes, it has to be between the sediment bowl and the carb. There is a screen at the top of the sediment bowl but I didn't check that while in the field but it almost has to be getting blocked. Since I just cleaned the sed bowl out the last time I used it and it already had more dirt in it this time I have to assume the tank has rust in it. This happened 10-15 yrs ago also but then the rust was getting through to the carb so it just ran rough until the carb was cleaned.
 
Yes, it has to be between the sediment bowl and the carb.

Or the float valve could be sticking. Have you tried tapping on the side of the carb with the handle of the screwdriver when the problem happens?
 
No, actually I haven't tried that, guess I can do that too next time. Would hate to change out the tank for nothing. But I am seeing the fines in the sed bowl so I'm fearing the worst.
 
[q
uote="labjack"](reply to post at 14:16:16 03/29/19) [/quote]
Well, the problem seems to be getting worse, it's running less and less time before stalling out. I guess too much rust/sediment is getting into the carb. So I guess it's time to get a new tank, or is putting an inline fuel filter a viable option? That would be much cheaper and easier but not sure if it's a good thing to do. Obviously, the carb will need a cleaning/rebuild too. What do you guys think?

Mark
 
(quoted from post at 09:06:03 04/04/19) [q
uote="labjack"](reply to post at 14:16:16 03/29/19)
Well, the problem seems to be getting worse, it's running less and less time before stalling out. I guess too much rust/sediment is getting into the carb. So I guess it's time to get a new tank, or is putting an inline fuel filter a viable option? That would be much cheaper and easier but not sure if it's a good thing to do. Obviously, the carb will need a cleaning/rebuild too. What do you guys think?

Mark[/quote]

Like I suggested before, do you have the carburetor inlet screen that many of them have? This would be after the sediment bowl.
 
I'm not sure. There is a screen at the top of the sediment bowl though. Apparently some of the rust fines go right through it. Where exactly would the one you're talking about be?
 
(quoted from post at 18:43:19 04/04/19) I'm not sure. There is a screen at the top of the sediment bowl though. Apparently some of the rust fines go right through it. Where exactly would the one you're talking about be?

Disconnect the small line that goes from the sediment bowl to the carb at the carb end. The small screen he is talking about would be inside that fitting if it is there.
 
Ok, will check that out. But what about the inline filter? Would that be a viable alternative to replacing the tank for the ultimate fix?
 
(quoted from post at 21:08:02 04/04/19) Ok, will check that out. But what about the inline filter? Would that be a viable alternative to replacing the tank for the ultimate fix?

I wouldn't be replacing the tank. Siphoning the tank once a year and normal maintenance of the screens would be completely adequate. The inline filters are known to be problematic.
 
(quoted from post at 21:59:52 04/06/19) So, I checked between the sed bowl line and the carb and there is no screen. Should there be?

Sorry, when I read showcrop's post about the carb inlet screen I assumed that it was a later 3 cylinder model as those are the ones that I am aware of that had that. I've never seen a carb inlet screen on a pre-65 4 cylinder.
 
(quoted from post at 06:10:25 04/07/19)
(quoted from post at 21:59:52 04/06/19) So, I checked between the sed bowl line and the carb and there is no screen. Should there be?

Sorry, when I read showcrop's post about the carb inlet screen I assumed that it was a later 3 cylinder model as those are the ones that I am aware of that had that. I've never seen a carb inlet screen on a pre-65 4 cylinder.

I don't have any three cylinders. One of my four cylinders has the inlet screen, but it is easy for them to just get removed and tossed and a later owner would never know.
 
So I guess I could just make one out of some fine mesh screen. It would be one more thing for the dirt to get through before getting into the carb.
 
(quoted from post at 16:06:57 04/07/19) So I guess I could just make one out of some fine mesh screen. It would be one more thing for the dirt to get through before getting into the carb.

You could possibly make one. The original fits into a 1/8 male by 1/8 female and is held in place tightly by a 1/4 compression sleeve. I wouldn't bother though. The screen at the top of your sediment bowl is completely adequate. Just review all the posts and make sure you have followed the recommendations and you will be good.
 

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