Poor fuel flow on 773 with Kubota V2203

[bobbie-g]

OK, sports fans, here's an easy problem to solve: 773 with the V2203 Kubota engine, 1100 hrs, original owner, never abused or neglected. Died abruptly under load. After troubleshooting, found the pickup tube in the fuel tank had fallen off. No surprise there. New pickup tube from Bobcat installed (including new strainer/check-valve, and the teensy clips for the pickup tube), also new hoses from the pickup elbow all the way up to the high pressure injector pump, new primer bulb, new fuel filter (tried two now), and new lift pump (actually tried two new pumps). Swapped the primer bulb from the new to the old and back again, no change. The "primer valve" at the input to the injector pump is turned off (open to prime the system, closed to run). And we've reversed the inlet and outlet lines on the lift pump, just in case we had those backwards (we didn't). Here's the rub: runs fine under light load for half an hour, but stalls under load. Once it stalls, walking behind and pumping the primer bulb will keep it running enough to get it into the shop. Disconnecting the fuel line at the input to the injector pump only gives a dribble of fuel when cranking the engine, so that's not what it should be. But, connecting a Holley electric fuel pump in place of the primer bulb lets the machine run under load at full throttle. So this is a simple fuel supply issue. But what gives here??? This is a really simple problem, isn't it? What am I missing? Why haven't the prev steps solved the problem? I think it's extremely unlikely the lobe driving the fuel pump partially broke off, but I sure can't come up with anything else that would be the cause. I think the last test will be to cut the line going into the injector pump and install the Holley pump there. That will let the Holley suck fuel from the tank all the way through all the components. Opinions? ---Bobbie-G

 

[foton]

I think if I was to do it I would put a shut off valve at the tank ( It would give you a easy place to be able to turn off fuel when working on fuel system) then the electric low pressure pump (2.5 to 5 psi) wired thru the switch . And take out or disconnect the manual lift pump.

 

[flyerdan]

I think if I was to do it I would put a shut off valve at the tank ( It would give you a easy place to be able to turn off fuel when working on fuel system) then the electric low pressure pump (2.5 to 5 psi) wired thru the switch . And take out or disconnect the manual lift pump.

It sounds like it's a lift pump issue, if it was working before the pickup line fell off, have you tried the original lift pump again? It could be that the replacements have a different arm that aren't allowing a full stroke, which is why they would work at idle and bench test ok. A few quick measurements should determine if the contact area is the same.

 

[bobbie-g]

It sounds like it's a lift pump issue, if it was working before the pickup line fell off, have you tried the original lift pump again? It could be that the replacements have a different arm that aren't allowing a full stroke, which is why they would work at idle and bench test ok. A few quick measurements should determine if the contact area is the same.

Tnx for responses. We also ran it with the fuel cap loose, just in case the vent in the cap was plugged and we were pulling a vacuum on the tank: no change. :-( And yes, we did try it with the original lift pump, no joy there either. Next step in a week or so is to pull the new pickup tube back out of the tank and make sure it looks OK. Tnx again for suggestions. I'll post resolution when we have it. ---Bobbie-G

 

[Tazza]

Tnx for responses. We also ran it with the fuel cap loose, just in case the vent in the cap was plugged and we were pulling a vacuum on the tank: no change. :-( And yes, we did try it with the original lift pump, no joy there either. Next step in a week or so is to pull the new pickup tube back out of the tank and make sure it looks OK. Tnx again for suggestions. I'll post resolution when we have it. ---Bobbie-G

Sure is an odd issue, the only thing left is the fuel line?

 

[bobbie-g]

Sure is an odd issue, the only thing left is the fuel line?

Here's the close-out for you avid forum readers: I'll spare us all of the gory details, but this seems to have turned out to be simple. 1) the fuel pickup tube fell off. Replaced it and that should have been the end of the story. But, 2) at that point the tank was topped off and probably ended up with a few gallons of gasoline mixed in with the diesel. Engine would run fine until it got warm then bog down and die. Final fix was to drain the tank and add new fuel. Things seem to be fine now. Are there a couple of lessons here??? ---Bobbie-G

 

[Tazza]

Here's the close-out for you avid forum readers: I'll spare us all of the gory details, but this seems to have turned out to be simple. 1) the fuel pickup tube fell off. Replaced it and that should have been the end of the story. But, 2) at that point the tank was topped off and probably ended up with a few gallons of gasoline mixed in with the diesel. Engine would run fine until it got warm then bog down and die. Final fix was to drain the tank and add new fuel. Things seem to be fine now. Are there a couple of lessons here??? ---Bobbie-G

Never heard that it would run on a mix then shut down when warm, good to know that contaminated fuel can do this.

 

[PEVO]

Never heard that it would run on a mix then shut down when warm, good to know that contaminated fuel can do this.

stupid question? doesnt that 2203 lift pump have a primer pump atop of it? mine does ...but its a repower from a OTR reefer unit.

 

[Tazza]

stupid question? doesnt that 2203 lift pump have a primer pump atop of it? mine does ...but its a repower from a OTR reefer unit.

The factory motors don't, they just install a hand primer in line.