JD 4240 Miss fire

NY_JD4240

Member
JD4240
I recently rebuilt the engine as the compression was low and I could not get it started on a 75-degree day. Now the tractor will start right up on a 40-degree day almost instantly. I still have one issue.

When it starts, it will skip / miss fire for the first 5 seconds or so and then smooth right out. The tractor did this prior to rebuilding the engine if the temperature was below 60 degrees, but if the temperature was in the 70’s is would not miss.

The injection pump was rebuilt in 2013 and at the same time, the injectors were cleaned and new nozzles installed. Also the lift pump was replaced a few years ago.

Ideas?
 
(quoted from post at 07:42:37 11/07/17) Does it act the same with a full fuel tank??

Currently there is a little more that a half of a tank of fuel. And yes last summer it did not matter if the tank was full or empty, still the same symtoms.
 
I have both a 4240 and a 4020 with the non turbo 466, both do the same thing. It may be what Tim S said, but you are not alone. I'd suggest you don't lose too much sleep over it, as mine have done that for
years, and not gotten worse.

Can't say I hit on all 6 first thing in the morning, either.
 
SO I replaced the fuel filter base with one from a 4440 (duel filter base). This is a NOS unit and has a built in check valve to prevent fuel from pushing back into the tank.

This did not resolve the issue.

Any problem if I install an injection pump from a 4430 (I have a set of fuel lines already)?

Thanks
 
I know I'm responding to an old post of mine regarding my 4240 skipping on start up.

The issue was that the housing on the injection pump was worn out. The worn housing allowed hydraulic pressure (diesel fuel pressure) to by-pass the Automatic Advance Piston. In other words the cam was not rotating to the advanced position to aid in starting.
The housing was relatively cheap, less than $100.00 ( I think $75.00 to be exact), to install it was not cheap.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top