345 — Fuel pours from fuel pump overflow tube

[NY 345]

A mystery (to me) that I hope someone here can help me solve. I have a JD 345 — around a 1999 model. I recently replaced what I think was the original fuel pump because it was leaking out the weep hole after shut down. The new pump has a rubber overflow hose instead of a weep hole (which was a terrible fire hazard), which gets routed down through a hole in the frame. New pump has worked fine for the several weeks that it’s been on the machine — until today.

Around 20 minutes into cutting the grass today I started to smell gas. Stopped the machine, looked underneath, and saw a relatively heavy flow (2-3 drops every couple seconds) coming from the fuel pump overflow tube end beneath the frame. The drips stopped after a minute or so. Thinking I might have filled the fuel tank too high and interfered with the return line, I took some fuel out of the tank and tried again. This time the fuel pump overflow tube stayed dry for a 2-3 minute test run. However, once I shut off the engine, fuel began pouring out of the fuel pump overflow tube and continued to pour until I applied a clamp to the tube to stop the flow. During that time, at least a quart of fuel flowed from the tube and there was no sign of it slowing down until the clamp went on.

I’ve looked around online but haven’t found another discussion of this set of circumstances. If anyone has any insight, I’d be grateful to have it. Thanks in advance.

 

[PTmowerMech]

A mystery (to me) that I hope someone here can help me solve. I have a JD 345 — around a 1999 model. I recently replaced what I think was the original fuel pump because it was leaking out the weep hole after shut down. The new pump has a rubber overflow hose instead of a weep hole (which was a terrible fire hazard), which gets routed down through a hole in the frame. New pump has worked fine for the several weeks that it’s been on the machine — until today.

Around 20 minutes into cutting the grass today I started to smell gas. Stopped the machine, looked underneath, and saw a relatively heavy flow (2-3 drops every couple seconds) coming from the fuel pump overflow tube end beneath the frame. The drips stopped after a minute or so. Thinking I might have filled the fuel tank too high and interfered with the return line, I took some fuel out of the tank and tried again. This time the fuel pump overflow tube stayed dry for a 2-3 minute test run. However, once I shut off the engine, fuel began pouring out of the fuel pump overflow tube and continued to pour until I applied a clamp to the tube to stop the flow. During that time, at least a quart of fuel flowed from the tube and there was no sign of it slowing down until the clamp went on.

I’ve looked around online but haven’t found another discussion of this set of circumstances. If anyone has any insight, I’d be grateful to have it. Thanks in advance.

Do you have a gravity fed carburetor or is the fuel tank under your seat? I'm having the same problem with my LX188, in which mine tank is under the seat, and has what looks like a heavy duty fuel pump.
I just put a new carburetor on mine, and it still does it. Was about to replace the pump, when I noticed online many others who replaced their pump had no success is solving their problem.
But a couple of things I have noticed, these after market carbs are for gravity fed carbs. And so the distance the needle has to travel to seat, needs to be shorter. So tomorrow, I'm going to make some adjustments to shorten that distance and see if that helps.
There's something that keeping the needle from seating. And therefore allowing way too much gas into the float bowl. Which gets pushed out the top vent. Yours just may be trash around the seat.

Also, be absolutely sure to check your oil before you crank it again. The carb is higher than the engine. So if there's a lot of excess fuel going into your carb, it's probably in your oil.

 

[NY 345]

Thanks for the reply and suggestions, PT. As I thought through the symptoms some more, I became persuaded that the problem had to be in the fuel pump -- some kind of diaphragm failure, probably -- even though it was brand new. I just didn't see a better explanation for how so much fuel could travel from the tank fuel line (tank is under the seat), into the upper chamber of the fuel pump (where the line enters), down to the lower chamber of the pump, and then out the pump's overflow line. I have now tested that theory by buying and installing yet another new fuel pump. I've only put about two hours on the clock since then, but I've had no problems so far.

The other information I should probably add is that the first fuel pump I installed was not OEM, but was billed as a good substitute for the relatively bargain price of about $65. I have now replaced it with a Deere OEM fuel pump that cost $165. Hopefully this one lasts a while.

 

[bertsmobile1]

IT really gets boring having to say this day in & day out
Cheap parts bought from Scamazon or Evilpay are a lucky dip
If it is tog good a price to be true then it is not true .
Just like on face book when you can not be held to account you can do any criminal - anti social behaviour with impunity .
Buy from real mower parts outlets that have a street address where you can go throw a brick through the front window if the parts you get are bad .
If you can not find the person who sold you the just to punch his lights out then he is free to sell you junk day in & day out ,
You now have to get it through your head that trying to save $ 100 has cost you an extra $ 65 so the pump is now a $ 230 pump.

 

[NY 345]

Fair point about the parts source, mostly. The first one was a Stens, which is a pretty big name in replacement parts, not a no-name knock-off from Amazon. And the bad part had a 1 year warranty, which they honored by refunding the full purchase price, no questions asked. So at this point, I do not, in fact, have a $230 fuel pump. And I was really only drawn away from OEM in the first place because Deere’s $165 price tag is obscenely high for that part. In other words, it wasn’t that the Stens was too good to be true, it was that the Deere was a gouge that was worth trying to avoid. The gamble didn’t work out, but so it goes sometimes.

 

[bertsmobile1]

OK
I will take that back
I use a lot of Stens, Rotary Oregon & Locally made parts and have only ever had quality problems fro one supplier Jak-Max who I no longer deal with

 

[PTmowerMech]

Thanks for the reply and suggestions, PT. As I thought through the symptoms some more, I became persuaded that the problem had to be in the fuel pump -- some kind of diaphragm failure, probably -- even though it was brand new. I just didn't see a better explanation for how so much fuel could travel from the tank fuel line (tank is under the seat), into the upper chamber of the fuel pump (where the line enters), down to the lower chamber of the pump, and then out the pump's overflow line. I have now tested that theory by buying and installing yet another new fuel pump. I've only put about two hours on the clock since then, but I've had no problems so far.

The other information I should probably add is that the first fuel pump I installed was not OEM, but was billed as a good substitute for the relatively bargain price of about $65. I have now replaced it with a Deere OEM fuel pump that cost $165. Hopefully this one lasts a while.

I seen too many instances where people have replaced their fuel pump only to have the same issue. But a possible theory about these fuel pumps were that they were simply pumping too hard, and forcing the float to submerge in the bowl via too much fuel pressure. Therefore unseating the needle.
So, I disconnected the fuel line from the carb, turned the engine over and watched the gas coming out. And it clearly wasn't much more pressure (if any) than a typical fuel pump. But without having a fuel pressure gauge, I didn't know for sure.
But with that possibility in mind, shortening the travel of the float made sense because it would take more fuel pressure to submerge the float.

Having a new pump, in my way of thinking, would create even more pressure simply because it's new. I've never heard of a fuel pump being worn out and pumping harder.

P.S. I couldn't find this carb at stens. And I really didn't want to spend the $300+ on an OEM carb. I got lucky, sort of speak. And usually do with the Amazon carbs I've been getting lately. Bert's right, it is a crap shoot buying them. But when the difference is $300, it's worth the chance.