I recently picked up a 4500 with a no start issue and it's got me stumped.
Story from the previous owner is that it would run fine, always started, never had any problems and then on time after it sat for a year or so it wouldn't start. He fiddled with some things then got busy and gave up and sold it.
I found the in tank filter screen plugged up with a ton of junk and maybe some water in the tank. (thought it was water at the time, now I'm not sure) I cleaned the screen, drained filters & tank and refilled with fresh fuel. I've bled the filters and the bleed screw on the pump and have a good gravity flow of fuel to the pump through both supply lines. I have a solid clean stream of fuel out of the pump bleeder screw when the engine is cranked.
Problem is that I'm not actually injecting any fuel. With the lines disconnected from the injectors I get a nice shot of fuel, but it's not making enough pressure to pop the injectors once the lines are tight. I've done quite a bit of cranking and fiddling thinking it needed bleeding but to no avail. I have pop tested the injectors and all 3 pop at ~2500 psi. 2 of them only squirt out one of the 4 nozzle ports and I have new ones on order, but even with that it should still be injecting fuel and it's not. I've connected the injectors upside down so I can be absolutely certain if they're working and there's not a drop of fuel out of the nozzles.
I have removed and mostly disassembled the injection pump thinking it's a pump problem but there's nothing obviously wrong or at all damaged - everything inside looks clean and nice and I actually think it was rebuilt recently. I had specifically checked to make sure the metering valve was free before taking it off and it was.
Any ideas on what to look for? I was expecting to find something stuck or gummed up but everything looks nice. I'm not really familiar with these pumps through, first one of these I've messed with. It seems to me that I have good transfer pump function, but for some reason no or not enough actual injection pressure. Worn hydraulic head could certainly cause that, but I don't think it would suddenly show up as a no start issue.
Story from the previous owner is that it would run fine, always started, never had any problems and then on time after it sat for a year or so it wouldn't start. He fiddled with some things then got busy and gave up and sold it.
I found the in tank filter screen plugged up with a ton of junk and maybe some water in the tank. (thought it was water at the time, now I'm not sure) I cleaned the screen, drained filters & tank and refilled with fresh fuel. I've bled the filters and the bleed screw on the pump and have a good gravity flow of fuel to the pump through both supply lines. I have a solid clean stream of fuel out of the pump bleeder screw when the engine is cranked.
Problem is that I'm not actually injecting any fuel. With the lines disconnected from the injectors I get a nice shot of fuel, but it's not making enough pressure to pop the injectors once the lines are tight. I've done quite a bit of cranking and fiddling thinking it needed bleeding but to no avail. I have pop tested the injectors and all 3 pop at ~2500 psi. 2 of them only squirt out one of the 4 nozzle ports and I have new ones on order, but even with that it should still be injecting fuel and it's not. I've connected the injectors upside down so I can be absolutely certain if they're working and there's not a drop of fuel out of the nozzles.
I have removed and mostly disassembled the injection pump thinking it's a pump problem but there's nothing obviously wrong or at all damaged - everything inside looks clean and nice and I actually think it was rebuilt recently. I had specifically checked to make sure the metering valve was free before taking it off and it was.
Any ideas on what to look for? I was expecting to find something stuck or gummed up but everything looks nice. I'm not really familiar with these pumps through, first one of these I've messed with. It seems to me that I have good transfer pump function, but for some reason no or not enough actual injection pressure. Worn hydraulic head could certainly cause that, but I don't think it would suddenly show up as a no start issue.
