sandybeach
Bronze Member
Branson 3510h, about 4 years old, 575 hours on the tractor, 1 1/2 years and 175 hours on the engine (and injector pump and injectors). The engine is newer because the original was replaced under warranty.
Problem: the engine surges frequently. It changes RPMs up and down, without my help.
To troubleshoot - and hopefully fix the problem - I changed the fuel filter and air filter. The air filter was dirty. The fuel filter didn't look bad - no debris, but obviously had been used a while (100 hours). I bled the air out at the bleeder screws on the fuel filter assembly. There was good flow of fuel coming out at the screws, so fuel flow into the filter and out to the injector pump is good. But fuel flow out of the pump to the injectors seems weak. At the nut at the injector ends of the fuel lines, fuel sprays instead of flows. I'm probably wrong, but I thought the spraying should be at the injectors inside the head, not at the nut at the end of the fuel line that delivers fuel to the injectors.
Sometimes I can get the engine to idle for several minutes at 650 RPM and at 2100 RPM, and most speeds in between. However, sometimes the RPMs go up up and down on their own.
The throttle lever (the one on the side of the console in the cab) and cable seem to work fine when the engine is off: full throw on the lever and full movement where the cable connects to the throttle (which I assume is inside the injector pump). But when the engine is running, sometimes a tiny movement of the throttle lever - less than a half inch either up or down - can cause big movement in RPMs. Once in a while I can adjust the speed with wider throw on the lever.
Worse, it has low power at any RPMs. Even as high as 2100-2500 RPMs, raising the bucket drops the RPMs rapidly - as in kills the engine - if I don't give it more throttle (to keep from stalling). Same for driving up a very slight incline - it wants to stall unless I futz with the throttle lever.
At the dealer's recommendation I added 1/2 can of fuel additive ("Sea Foam") to the tank.
Any ideas here?
I'm already planing for the worst case: R & R the $600 injector pump. That project looks nasty. There's fuel lines (running from the pump to the injectors) sitting behind other stuff. (Who designed that?) Or have the dealer do it: sending out a mechanic adds a $200 trip charge and $200 or so for labor. I guess my daughter will have to get married some other year.
Problem: the engine surges frequently. It changes RPMs up and down, without my help.
To troubleshoot - and hopefully fix the problem - I changed the fuel filter and air filter. The air filter was dirty. The fuel filter didn't look bad - no debris, but obviously had been used a while (100 hours). I bled the air out at the bleeder screws on the fuel filter assembly. There was good flow of fuel coming out at the screws, so fuel flow into the filter and out to the injector pump is good. But fuel flow out of the pump to the injectors seems weak. At the nut at the injector ends of the fuel lines, fuel sprays instead of flows. I'm probably wrong, but I thought the spraying should be at the injectors inside the head, not at the nut at the end of the fuel line that delivers fuel to the injectors.
Sometimes I can get the engine to idle for several minutes at 650 RPM and at 2100 RPM, and most speeds in between. However, sometimes the RPMs go up up and down on their own.
The throttle lever (the one on the side of the console in the cab) and cable seem to work fine when the engine is off: full throw on the lever and full movement where the cable connects to the throttle (which I assume is inside the injector pump). But when the engine is running, sometimes a tiny movement of the throttle lever - less than a half inch either up or down - can cause big movement in RPMs. Once in a while I can adjust the speed with wider throw on the lever.
Worse, it has low power at any RPMs. Even as high as 2100-2500 RPMs, raising the bucket drops the RPMs rapidly - as in kills the engine - if I don't give it more throttle (to keep from stalling). Same for driving up a very slight incline - it wants to stall unless I futz with the throttle lever.
At the dealer's recommendation I added 1/2 can of fuel additive ("Sea Foam") to the tank.
Any ideas here?
I'm already planing for the worst case: R & R the $600 injector pump. That project looks nasty. There's fuel lines (running from the pump to the injectors) sitting behind other stuff. (Who designed that?) Or have the dealer do it: sending out a mechanic adds a $200 trip charge and $200 or so for labor. I guess my daughter will have to get married some other year.
