4000, 3 cyl diesel Surging

4000 started surging and finally quit last year while I was working it HARD. Changed the fuel filter per recommendations here and it stopped surging and ran fine. It started doing it again this spring wile plowing. Changed the fuel filter again, however, this time the surging has not completely stopped. Tractor does not quit and it doesn't surge all the time. I am running good clean Valero fuel. Where should I start looking? Ideas?

Bill

The fuel shutoff valve in the tank has a screen in it that can get full of trash and restrict fuel flow.
You need to siphon as much full out of the tank as possible before removing the valve or connect a vacuum cleaner to the fill neck to suspend the fuel, otherwise you'll have fuel pouring out all over the place.
If the screen has come off there could be trash in the valve.

(quoted from post at 09:50:31 07/10/16)
The fuel shutoff valve in the tank has a screen in it that can get full of trash and restrict fuel flow.
You need to siphon as much full out of the tank as possible before removing the valve or connect a vacuum cleaner to the fill neck to suspend the fuel, otherwise you'll have fuel pouring out all over the place.
If the screen has come off there could be trash in the valve.

Click to expand...

connect a vacuum cleaner to the fill neck to suspend the fuel,

what could go wrong with that?? sucking fumes through a motor with brushes sparking under high pressure of the fans.... !!!!!!!!!!!!!!!!!! yes, I know its only diesel, but the preheaters on military diesel generators are built exactly that way and creates a nice JET exhaust when it finally lights up.... be sure to take lots of pictures...

Does choking it hurt or help?? If it helps it is running lean so you may have a clogged fuel system some place. Also when was the last time you serviced the air cleaner??

(quoted from post at 09:12:53 07/10/16)

(quoted from post at 09:50:31 07/10/16)
The fuel shutoff valve in the tank has a screen in it that can get full of trash and restrict fuel flow.
You need to siphon as much full out of the tank as possible before removing the valve or connect a vacuum cleaner to the fill neck to suspend the fuel, otherwise you'll have fuel pouring out all over the place.
If the screen has come off there could be trash in the valve.

Click to expand...

connect a vacuum cleaner to the fill neck to suspend the fuel,

what could go wrong with that?? sucking fumes through a motor with brushes sparking under high pressure of the fans.... !!!!!!!!!!!!!!!!!! yes, I know its only diesel, but the preheaters on military diesel generators are built exactly that way and creates a nice JET exhaust when it finally lights up.... be sure to take lots of pictures...

Click to expand...

Bill, Those preheaters have an air INTAKE, along with the discharge. In order for the suction to hold the fuel there cannot be an air intake, so there would be little to no movement of fumes.

(quoted from post at 12:58:39 07/10/16) Does choking it hurt or help?? If it helps it is running lean so you may have a clogged fuel system some place. Also when was the last time you serviced the air cleaner??

Click to expand...

I don't think a diesel has a choke.

Did not notice he said diesel.

I get a kick out of people worried about using a vacuum on a diesel tank to hold the fuel up but then they'll go welding on the same tank... A small volume of vapor in a large volume of air generally creates a mixture below the explosive range, if indeed there even was an ignition source.

First thing I'd check is the o-rings and quad rings on the filter. Did you change the ring on the stem bolt? I usually don't because it's hard to get out on those models.... but eventually it will leak and draw air... and then you get that surge at idle. So I'd probably pull the filters off and change the o-rings again and while I'm at it... check to see if there's good strong steady flow coming from the tank. If not, then I'd remove the shutoff valve from the tank.... and yes, I use a vacuum, regularly, to do that. You don't shove the hose in tight. You allow it to draw outside air and just enough air from the tank to hold the fuel up. I don't know about anyone else's shop vac... but mine draws air through a pump made from pvc, not a motor winding. I don't even give it a second though. Just don't shove the hose in tight or you could collapse the tank.

Rod

Destroked, Would I mess thing up if I removed in line from the filter and blew air up into the tank, maybe 30 psi, or should I start with
less?

Bill

When blowing air back into the tank you take a chance on blowing the screen off the shutoff valve, with it off any piece of thrash rolling around in the tank can drop down in the valve and stop it up (been there, had that happen).

Like RodinNS said, take the filter off and open the valve on the tank to see if you have good flow, if not I'd pull the valve and clean the screen, let some fuel run out of the tank to flush out any trash that be in the bottom.