Frustrating fuel issue...

[pomester]

...I don't know what to do next.

My '65 4500, 3 cylinder gasoline. In use and running well when the water pump went out last week. Replaced the water pump and now suddenly have fuel issues.

The tractor runs for 20-30 minutes and then starves for fuel. Let it set for 30-60 minutes and it starts right up and runs for another 20-30 minutes and then starves for fuel. No warning, runs fine until it runs out of gas and stops. Like a switch was thrown, no struggling. Pulling the choke causes it to fire back up for a short time as one would expect.

The machine has a Zenith carburetor that I've been running for 9 years (I purchased the carb new during the machine's resurrection in 2017). The fuel inlet on the carb is toward the block and there is a plug opposite the inlet. When it starves for fuel, I can remove the plug and crank the engine and see no fuel. When cold and I remove the plug gasoline pulses out just as one would expect when the engine is cranked.

So, bad fuel pump, right? I removed it (but did nothing to it, just laid it aside) while replacing the water pump, maybe something happened...

I installed a new fuel pump and the symptoms remain the same. Runs while cool, starves for fuel when warm. The engine is not overheating, I'm not working it hard and it's very comfortable. Coolant level is appropriate and maintains.

I have:
1. Checked for venting of the fuel cap - makes no difference even running without the cap. Will not pump fuel when warm with cap removed.
2. Removed the line from the valve at the bottom of the tank. Fuel pours out when the valve is opened.
3. Took the cap off the (new) fuel pump (in place), opened the valve on the tank - fuel spills out the pump.
4. Removed and cleaned the small glass settling bowl under the carburetor. Fuel pulses out when the engine is cranked (while cold, not when starved for fuel).
5. Removed and cleaned the carburetor.
a. checked/cleaned the small screen associated with the inlet (it was clean).
b. removed the bowl and cleaned with cleaner and compressed air (it was nastier than I expected).

Nothing has made a difference.

It runs smoothly and then suddenly starves for fuel. Pulling the choke causes it to fire back up for a short time.

Still seems like a bad fuel pump. So a brand new fuel pump intermittently fails, out of the box, in the same manner as the 9 year old fuel pump intermittently fails after a bit of unrelated mechanical work? But both work seemingly fine for 30 minute stints?

I've got another pump. I can think of nothing else to do except swap pumps again. I'm not optimistic.

Any thoughts? Any suggestions? Frustrating.

Thanks
David

 

[Sean in PA]

Partially blocked return line?

 

[joeysmith]

Sure sounds like its vapor locking
It have a temp gauge?
Tried cooling the fuel line thats close to the block when it quits?

 

[pomester]

Partially blocked return line?

No return line on gasoline engines.

 

[pomester]

Sure sounds like its vapor locking
It have a temp gauge?
Tried cooling the fuel line thats close to the block when it quits?

I have to agree, it sounds like vapor lock. The temperature gauge does not work. All I can say is that dealing with tractors for 60+ years, this is not a hot engine. I was able to remove the generator to access the fuel pump with my bare hands immediately following a shutdown from fuel starvation. Working right next to the exhaust manifold and engine block. No boiling coolant or smoking oil residue. Dunno. Guess I could check it with the infrared thermometer, but I don't have any previous baseline.

One thing I have changed is I started running pump gas from the gas station nearby, hoping to stretch the farm tank so I don't have to have it filled in August for who knows how much a gallon. My farm tank has 90+ no ethanol gasoline while the pump gas is 87 w/ethanol. I'd be inclined to syphon the tractor tank empty and try some 90+, but all my gas cans are full...

Not sure how to go about cooling the lines/pump - most of that is buried pretty well.

It's a new issue. I've used this machine which is pretty much dedicated to raking prunings out of the orchard for 9 seasons now. Never had this issue.

thanks

 

[Sean in PA]

Sorry... missed that it was a gasser on my first read through. Sounds like it might be the coil going bad. They usually start showing symptoms when they get warm after the engine has been running for about 20 to 30 minutes. You let it cool down and the coil woks fine again for another 20 to 30 minutes. Over time (weeks or months depending on how much it is run) , the coil will start having problems at lower and lower temperatures, which means shorter and shorter run times before the problem happens.

 

[Check Break]

Unfortunately, new parts are not what they used to be. Change out the new fuel pump so you know for sure. I have a Ford 6.0 that gave me fits a couple of years ago. OEM starter died in a bad spot so one of my guys installed a Napa starter in the TSC parking lot. I knew it wasn't going to last but I got lazy and ran it for about two years before it exhibited intermittent starting problems. Since it was under warranty, Napa gave me a new one, but I still had the intermittent starting problems. Had the new starter checked out by the local rebuilder. All was well. Another starter didn't make sense so I began tracing wires. This went on for weeks between failures. Started at the key switch and concluded that it was the trigger wire so I replaced the trigger wire which was a nightmare. The intermittent failures didn't go away, so exasperated, I pulled the new starter and figured out it had a loose terminal on the solenoid. Replaced the solenoid and the failures went away. Ordered a Mean Green starter and wished I'd installed it years before. So, moral of the story is, the cause of the original Napa starter's intermittent failure was not the same as the cause of the second Napa starter's intermittent failure, but they were both junk, so although replacing your new fuel pump doesn't make much sense, you need to rule out new fuel pump failure before you beat yourself up any further.

 

[Blue Jay]

I had a 64 4000 that did the same thing, gravity flow no fuel pump, was told it could not be vapor lock (right) I re routed the fuel line away from the exhaust manifold and pretty much solved the problem.

 

[Sean in PA]

I had a 64 4000 that did the same thing, gravity flow no fuel pump, was told it could not be vapor lock (right) I re routed the fuel line away from the exhaust manifold and pretty much solved the problem.

Fuel boiling in the fuel line is not vapor lock. It can cause similar symptoms, but not the same cause.

 

[Eman85]

Have you looked in the tank? trash might allow flow for a while until it gets sucked against the screen in the tank.

 

[Hemmjo]

I once has a similar issue. I have a fuel shed away from the barn where I store all fuels, cans funnels etc. Funnel hangs on a nail in the shed. While trouble shooting the stalling issue, I found some "gooey" fibrous material floating around in the tank. Turned out, spiders had been building in the funnel. Every time I filled the tank, more spider web got flushed into the tank. Eventually so much got stuck on the little screen in the inside the tank to restrict flow. it would idle all day, but soon after a load was applied. Then start right back up.

The spider web restricted flow, but did not cut it off completely. My funnel now sits with the tip in a can with a little oil in it and a rag in the big part.

It is also important to note, spider web is nearly invisible in gasoline. It is very hard to see it floating around in the tank, or stuck to the screen in the tank,

 

[davidpick]

I had the same probalem on my IH 504. It was the coil.

 

[cushman]

I had the same probalem on my IH 504. It was the coil.

I also experienced a condenser that did the same thing.

 

[davidpick]

yep, my 53' Packard had that problem, changed everything but that, replaced condenser jumped to life.

 

[pomester]

yep, my 53' Packard had that problem, changed everything but that, replaced condenser jumped to life.

In this case, when the tractor starts to lose power, closing the choke will allow it to pick back up and run for a short time until the carb empties. I am confident it is a fuel issue. My work with the brush pusher is 98% over for the year, maybe it will cure itself setting for a few months....

 

[Sean in PA]

Closing the choke makes it run leaner, which can help a little with a weak spark caused by the coil or condenser that is slowly going bad. Have you actually checked the spark when it is having the problem?

 

[Hemmjo]

Closing the choke makes it run leaner, which can help a little with a weak spark caused by the coil or condenser that is slowly going bad. Have you actually checked the spark when it is having the problem?

Curious, how does closing the choke make it run leaner?

Closing the choke drops pressure in the intake air passages. More fuel from the float bowl, at normal atmospheric pressure, flows into the air stream. This makes the Fuel/Air ratio more rich.... Doesn't it?

 

[TomIn]

I had the same probalem on my IH 504. It was the coil.

I had the same problem on my Ford 640. Once I had ruled out fuel problems I decided to replace the coil. When I tried to disconnect the hot wire to the coil, it broke while I was holding it. It turned out that the stranded wire had frayed inside the insulation. After running about a half hour, the wire would heat up from the resistance caused by only a strand or two of the wire carrying the current, and the tractor would quit. I replaced the section of wire and the tractor has been working fine for several years. I expect that the same problem could occur anywhere in the wiring.

 

[davidpick]

less air and more fuel= richer, I agree. Still think it's coil. You probally have a coil to swap out or you can buy one from Amazon cheap. Or like you said it could fix it self.

 

[davidpick]

I think you should start the tractor up, run a while and feel the coil and wire for heat. one or the other or both is probaly getting hot. or it could fix it self.