Bobcat 853 Isuzu 4 cylinder Fuel Problem at full throttle

[jimbob1000]

Hey everyone, new to the forum. I've been searching through posts, but can't seem to find a similar problem that I'm having. This machine runs fine / smooth at idle, but it dies out when I increase it to full throttle. I drained the fuel tank. I replaced the pickup tube and filter. I added an inline fuel filter, check valve, and electric fuel pump. I bled the line at the fuel separator and the injector pump. Idles like a champ, but when I open it to full throttle, it bogs down and dies. I'm a little lost, any help would be appreciated.

 

[jimbob1000]

Also, I changed out the air filters. I removed the hose to the air intake just to see if that was the issue. It helped the idle run a little smoother, but still had the same problem at full throttle. The engine itself was rebuilt about 100 hours ago, so I'm pretty sure it's not a compression issue. Again, any help would be awesome.

 

[Bswwood]

Also, I changed out the air filters. I removed the hose to the air intake just to see if that was the issue. It helped the idle run a little smoother, but still had the same problem at full throttle. The engine itself was rebuilt about 100 hours ago, so I'm pretty sure it's not a compression issue. Again, any help would be awesome.

The injection pump has an internal lift pump and that is usually the problem. Installing an electric pump will not work because the lift pump is stuck and fuel can not pass. Has the machine been sitting for a long time? I got one working again by filling fuel filter with Sea Foam, starting machine and letting idle until it shuts off. Let sit over night and install new fuel filter with fresh diesel, flush lines, and start machine and see if the internal lift pump will free up and start working.

 

[jimbob1000]

The injection pump has an internal lift pump and that is usually the problem. Installing an electric pump will not work because the lift pump is stuck and fuel can not pass. Has the machine been sitting for a long time? I got one working again by filling fuel filter with Sea Foam, starting machine and letting idle until it shuts off. Let sit over night and install new fuel filter with fresh diesel, flush lines, and start machine and see if the internal lift pump will free up and start working.

Thank you! It was sitting over the winter, so yeah. I figured out the problem however. I ended up just putting a fuel line down a fuel can to test each part separately to see if I could narrow down the problem. Started with the line straight to the fuel pump and it runs great at high RPM (Phew!) that's the expensive one! Then I moved it down the line past the check valve and the electric pump (replaces my bulb pump kinda), still working great at high RPM's. Then I moved it past the fuel filter and water separator and found the problem. I got one of those "fancy" glass sided fuel filters and found out that it was not screwed on tight (comes apart for cleaning) so it was letting air into the system. Tightened that up and now it runs great. I will keep the Sea Foam idea in mind though, sounds like a solid solution to a fuel injector problem.