Air in the tank?

[gjsnow]

Hi there...
I have a 1435 front mower re-powered with a 36 hp yanmar engine. Runs and starts great except when the fuel tank is low. Then it acts like there is air in the system requiring a bleed to turn over. All hoses have already been changed and double clamped. Fuel filter has been changed and the bowl cleaned. Solenoid sounds OK. I always use deere fuel conditioner and use a block heater when needed.
Any thoughts?? Could the two bushings on top of the tank be bad??
Thanks.

 

[mrtfelton]

There might be a metal mesh or screen in the bottom of the tank that gets full of debris when the tank is real low on fuel.

 

[Bird]

My first thought was a plugged fuel cap vent causing a vacuum in the tank as the fuel level goes down. That would slow or stop fuel flow.

 

[gjsnow]

Thanks for the quick reply.
The deere parts page which pictures the tank does not show any filter screen.

 

[gjsnow]

I don't think the cap is bad but I will double check. Also, the tractor had no problem running hard as I went through the last tank of fuel...
In other words, it did not act like it was not getting enough fuel. I started and stopped it many times. It only became a problem when I left it overnight in the shed with low fuel (definitely not empty) and tried to start it the next day before filling the tank.

 

[jenkinsph]

I agree with mrtfelton and Bird, but would also add the possibility of a cracked pickup tube to these suggestions. Temorarily loosen the vent cap and or clean it to eliminate that first, then see if you can remove the pickup tube and check for cracks or holes, blocked strainer screen ( probably has one).

Next, not to be offensive but could be a misdiagnosis, might have other problems. Are you sure you are getting air in the lines? How clean are your fuel filters?


Steve

 

[RadarTech]

Ya know, this reminds me of a quip I heard the other day when I was down at the truck stop by the interstate...

There was a guy dressed in fairly nice clothes for a country truck stop.
khakis and a nice polo shirt with penny loafers....

he had a gas can in his hand and was heading for the register...

he said he thought he could make it down the grade to the next town where it is $0.25 a gallon cheaper but was wrong.

when I asked how much gas his tank had when he passed the exit, he said it was full to the brim. 100% full with no room for absolutely any more air.
then he went on to say he had so much air in that tank that the gauge had to be wrong since the tank even spit at him when he opened it. he went on to talk about how was looking into selling the air his air producing gas tank was creating to NASA. All this with the most serious face I had ever seen!!!!

It took me a second before I actually starting laughing..

He had to be the calmest person I have every met in a situation where he should have beat himself up so bad for making a calculated error like this.......



sorry to interject-- just thought this was a funny antidote to add...


now for a point on Bird's and the other folks posts...

I have seen debris in gas tanks that will float when the tank is full but get sucked down when it is low...

A friend use to put mothballs in as a joke....

Clean the tanks and see what you find...

later,
J

.

 

[Labrat]

Are the fuel lines reversed? The return line dip tube doesn't go to the bottem of the tank like the pickup does.

 

[greggh]

Hi there...
I have a 1435 front mower re-powered with a 36 hp yanmar engine. Runs and starts great except when the fuel tank is low. Then it acts like there is air in the system requiring a bleed to turn over. All hoses have already been changed and double clamped. Fuel filter has been changed and the bowl cleaned. Solenoid sounds OK. I always use deere fuel conditioner and use a block heater when needed.
Any thoughts?? Could the two bushings on top of the tank be bad??
Thanks.

Do you have a reserve switch or fuel outlet you need to turn when the fuel gets low? Sometimes these are present to keep one from running the tank competely dry.

 

[gjsnow]

Thanks for all the advise.
I am confident the fuel lines are not switched because I don't think it would run.
I also would love to empty the tank and clean it and check all the lines in the tank. I have some fuel to use before that can happen. Also removing the tank on a front mower is a piece of work. It is entangled in the left frame.
My dealer suggested I place a one way valve in the fuel line that leaves the tank heading for the filter. He said that when the tank is low, the fuel may be backing up and it is hard to pull it all that distance. The one way valve would keep the fuel in the line when the tank goes down.
All the advise has been great. Once again, thanks.