Hi all, I have a problem that I am hoping someone can help me with. If my machine sits for a couple of days, it is hard to start. After lots of cranking and pumping the primer pump, I can get it to start. After it starts the engine will rev up and then back down or I would say it surges. If I mess with the throttle a little it will typically settle out. When I go to move it, if I go slow the engine will run smooth, if I push into the sticks a little the engine will begin to surge again. I have seen other posts with people experiencing similar problems, but I have not seen that it was resolved. I looked on the back of the engine but did not see a check valve (i may not know what I am looking for). I purchased it last fall an it ran an operated just great. I did not use it much through the winter and this problem has developed. I have replaced the fuel filter, air filters, hydraulic filter and the hydraulic vent filter, oil and oil filter. Any help would be appreciated, thanks.
One thought came to mind. Could it be a pressure relief valve?
Sounds like the fuel is weeping back to the tank when it sits for a couple of days. Does it eventually run smooth? If so probably just crud in the check valve, if it's a hand prime pump chances are the check valve is in it.
It just depends on what type of fuel system is on your machine as to how you go about diagnosing it. Some have Stanadyne rotary pumps, mechanical or electronic, some Robert Bosch inline pumps and some are unit injectors and pumps under the valve cover.. But the symptoms do lead to> fuel leak back.. most likely from the lift pump or overflow valve..
Thanks for the reply guys. I will dig into the fuel system and see what I can find. It does have the hand prime pump located on top of the fuel/water separator. I will start with that device. It hasn't been smoothing out after getting it started.
It has the unit injectors and pumps under the valve cover. How do you diagnose this type of fuel system.
.. it normally comes down to the lift pump..
Is this the same as what Deere is calling the Transfer Pump? Is this something I can change out or is it best to have a mechanic do the work. Deere show the prices of the fuel pump at $82 and the filter/prime at $47. I do most of my own maintenance on my vehicles and tractors. I am not a mechanic by trade but have good mechanical repair abilities. And thank you for your input.
lift pump, supply pump, fuel pump.. yes that's it.. I think if you search around or get the P#, you'll find it cheaper..?? ALOT of folks call the injection pump, the fuel pump, and that gets very confusing..
Well, just to follow up. Had the forwarding pump replaced but still wouldn't start. Deere hauled it in and ended up replacing the injectors. Still wasn't getting fuel and I believe they found the governor rod was hanging loose and not moving. I believe that was the real fix.
I would replace the check valve coming out of the head first. Looking at the engine from the rear it would be on your left side towards the flywheel end of the engine. It is the barbed fitting the return hose is attached to. That fitting is what maintains residual pressure in the rail. If it fails you have hard starting from fuel draining.