Zetor 4340 fuel issue

[porbarzet]

We have a Zetor 4340 that appears to have a fuel intake problem. The engine starts to stall when the tank gets to half empty. It starts fine and runs good on a full tank.

We started having this problem after a mechanic worked on unrelated issue but we think he did remove the tank. We do not use the tractor often so we did not discover it until sometime later and he was no longer available to look at it.

Any ideas?

Also, does anyone have a schematic of how the fuel lines should run? We want to trace the fuel system.

 

[hala]

It may suck some air due to an air-leak between the tank and the lift-pump Do you see any air-bubbles in the glass-bowel close to the lift-pump. I presume that you dont have any leakage of diesel that you can see. When the tank is full can you drive the tractor hard without any stalling? All fuel hoses had at that time a very poor quality and let air in quite often after some years so I have replaced all hoses to a better quality on my 4340. When the tank is half full it is tougher for the lift-pump so it may also be the lift-pump. How many hours on the tractor?
Hazze

 

[forterra9641]

have had this problem on a 7745 changed lift pump and all hoses but no Luck. the problem vas a cracked pipe inside the tank. i traced it to the tank when i made an emergency tank of a plastic can then it would not stall and all was normal. the newer tanks has the pipes welded into them so i got an older tank With pipes that are removable. changed too older tank and no more problems.

 

[forterra9641]

have had this problem on a 7745 changed lift pump and all hoses but no Luck. the problem vas a cracked pipe inside the tank. i traced it to the tank when i made an emergency tank of a plastic can then it would not stall and all was normal. the newer tanks has the pipes welded into them so i got an older tank With pipes that are removable. changed too older tank and no more problems.

Also if the mechanic had changed the intake pipe With the Return pipe you could get this problem Return pipe is Shorter than suction pipe. try to swap the hoses on top of tank first

 

[porbarzet]

This is a 1996 Zetor with 1600 hours.

 

[porbarzet]

We also want to add that this mainly occurs in bumpy terrain. Reminded of a time when the tank was 3/4 full but it was very bumpy and very hot day.

 

[hala]

I agree with Forterra to check, when the mechanic reassembled the tank, the hoses not was changed. If the hose to the lift - pump is connected to the return tube in the tank and the fuel ripples due to bumpy terrain the level can in some moments be very low and the lift-pump stars sucking air and the engine stalls or stop. Do you have air in the glass bowel? My theory is that the lift-pump is sucking air but why is harder to tell however listening to your description to the problem it seems that the problem is the tank, changed inlet and outlet tubes to the tank or broken tube inside the tank. If you take down the tank make sure that the 90 deg bend of the tubes going in to the tank is free from dirt, a classic problem to 4340. If the tube is almost blocked with dirt you might have the same symptom. If you taking down the tank install a new hose from the tank to the lift-pup.
Hazze