Deere w/Yanmar runs for half hour fine.

[coachlarry]

We have a Deere 2653A w Yanmar engine. Recently it has run "okay" for half hour then loses power and I have to disengage PTO to limp back to barn. I say "okay" because it doesn't quite feel 100% but it mows. Once it rests for a while I can go slither half hour. I drained tank and out in new fuel and sea foam. Changed oil and out new coolant in reservoir. It ran fine for half hour again but started losing again. I have read quite a number of posts about this with different machines but haven't found a really solid lead. The question of why after half hour is the main mystery. One guy found something in his fuel filter bowl that seemed to expand over time and clog it.

Here is a new clue hopefully: I have a primer bulb off the tank. Today, when it started dying I gave it a squeeze and the engine perked up on each squeeze.

Thank you.

 

[joecdeere]

Start at the tank checking flow, have you checked the strainer in the tank on the end of the pickup line? Looked in empty tank for trash, water, misc crap? Is the mechanical fuel pump feeding injection pump pumping? Walk it all the way through and I bet you'll find your problem. Have you reached back and loosened the fuel cap when it starts failing? Cap may not be venting. And pulling a vacuum.

 

[California]

Have you reached back and loosened the fuel cap when it starts failing? Cap may not be venting. And pulling a vacuum.

Over in the Yanmar forum that's a common problem, and solution. Some of them originally had a removable strainer in the fuel neck. If it's missing then the cap can be screwed on airtight causing what you describe.

 

[coachlarry]

Ok thanks guys. I'll work from the tank forward and check inside tank. I blew on cap and it was venting but not free flowing air. Not sure how freeflowing it's supposed to be. I'll pull cap next time. Haven't checked lines from injection pump yet but will get into the engine compartment after I check the tank and lift Pump.

 

[coachlarry]

Over in the Yanmar forum that's a common problem, and solution. Some of them originally had a removable strainer in the fuel neck. If it's missing then the cap can be screwed on airtight causing what you describe.

I think I understand better what you meant. The threaded neck pushes up against the diaphragm ceiling the vent. That would not have an effect on testing the flow of the cap by blowing in it. Interesting, I will check it out later today.

 

[coachlarry]

I had a chance to work on the mower and did not find anything near the tank that was suspicious. Turning my attention towards the fuel lines, I found the return line from the injectors appeared to be cracked at the clamp when I bent it. This seemed like a possible source of a slow air leak though I couldn't imagine the air at the point would cause a problem. I replaced the line as shown and put a hose clamp on it. The mower ran fine for an hour after I did that. There were a couple of times it bogged down on a hairpin turn but I was able to mow the lawn. Anyone think a crack at that point where the arrow is would cause the delayed stall I was having?

 

[rScotty]

I had a chance to work on the mower and did not find anything near the tank that was suspicious. Turning my attention towards the fuel lines, I found the return line from the injectors appeared to be cracked at the clamp when I bent it. This seemed like a possible source of a slow air leak though I couldn't imagine the air at the point would cause a problem. I replaced the line as shown and put a hose clamp on it. The mower ran fine for an hour after I did that. There were a couple of times it bogged down on a hairpin turn but I was able to mow the lawn. Anyone think a crack at that point where the arrow is would cause the delayed stall I was having?
View attachment 519758

I wouldn't have thought so. It seems like a crack there would help more than hurt. If it works, that's good....although I am another old mechanic who isn't comfortable by fixes that don't make sense. I'd almost rather think that you messed with the cap and it began to vent again.

Because to me those sympoms all sounded like the typical "vacuum in the fuel tank" caused by a non-venting cap. Those caps were originally designed to be taken apart and the vent cleaned. I didn't know about the strainer being part of the vent system.
Anytime I hear of anything that sounds like a fuel flow problem the first place I look to is the fuel filter and the lines to and from.
I once had a fuel tank that had small pools of water in the bottom. I could see them by shining a flashlight into the tank. Over the years they built up a small pool of water that got pushed though until I could see maybe a quarter inch at the bottom of the clear (cloudy) filter housing. But even so, there was no effect on running.
good luck,
rScotty

 

[coachlarry]

I wouldn't have thought so. It seems like a crack there would help more than hurt. If it works, that's good....although I am another old mechanic who isn't comfortable by fixes that don't make sense. I'd almost rather think that you messed with the cap and it began to vent again.

Because to me those sympoms all sounded like the typical "vacuum in the fuel tank" caused by a non-venting cap. Those caps were originally designed to be taken apart and the vent cleaned. I didn't know about the strainer being part of the vent system.
Anytime I hear of anything that sounds like a fuel flow problem the first place I look to is the fuel filter and the lines to and from.
I once had a fuel tank that had small pools of water in the bottom. I could see them by shining a flashlight into the tank. Over the years they built up a small pool of water that got pushed though until I could see maybe a quarter inch at the bottom of the clear (cloudy) filter housing. But even so, there was no effect on running.
good luck,
rScotty

Well rScotty, we may never know because I DID mess with the cap and have since kept it cracked. Did a 90 minute mow today and all was good. :laughing:

 

[TomSeller]

One of mine acted like this and it was simply the fuel filter

 

[Tx Jim]

I agree with rScotty that leaking diesel return line won't affect how engine runs but will make a smelly mess.