Hi,
I'm new to the Forum but I've read all posts I can find on this motor. Bought a used motor that ran OK for about 1 hour then problems developed. At 3800rpm motor begins to die/stumble if I give it any more throttle. Replaced Lift Pumps, VST pump filter, all filters prior to VST replaced, Medium pressure filter between VST and Mechanical pump replaced. Fuel pressure at 3800rpm is 56 psi in VST and YDS says 700 at Mechanical Pump. Any more throttle and the pressure in Mechanical pump drops below 600psi while VST pressure remains at 56psi. Does this sound like the filters in the Mechanical pump OR are there other serviceable parts in the Mechanical pump? I have the pump removed but have not taken it apart to look at the filters yet. If there are other serviceable parts in the pump then I need to send it to Flagship. I'm assuming that if they clean it they not only replace filters but all packing kits as well.
The guy that connected the YDS also removed fuel vent and return lines from VST tank to check them before we lake tested the motor. If they were reversed when reconnected could this be a possible cause for the pressure drop in the mechanical pump ? One of the lines "T's" to the starboard side of motor the other goes to a solid pipe on Port side which faces forward. Which hose is return and which is vent and which fitting on the VST forward or rearward gets vent (or does it matter).
Any help would be appreciated ...thanks
I'm new to the Forum but I've read all posts I can find on this motor. Bought a used motor that ran OK for about 1 hour then problems developed. At 3800rpm motor begins to die/stumble if I give it any more throttle. Replaced Lift Pumps, VST pump filter, all filters prior to VST replaced, Medium pressure filter between VST and Mechanical pump replaced. Fuel pressure at 3800rpm is 56 psi in VST and YDS says 700 at Mechanical Pump. Any more throttle and the pressure in Mechanical pump drops below 600psi while VST pressure remains at 56psi. Does this sound like the filters in the Mechanical pump OR are there other serviceable parts in the Mechanical pump? I have the pump removed but have not taken it apart to look at the filters yet. If there are other serviceable parts in the pump then I need to send it to Flagship. I'm assuming that if they clean it they not only replace filters but all packing kits as well.
The guy that connected the YDS also removed fuel vent and return lines from VST tank to check them before we lake tested the motor. If they were reversed when reconnected could this be a possible cause for the pressure drop in the mechanical pump ? One of the lines "T's" to the starboard side of motor the other goes to a solid pipe on Port side which faces forward. Which hose is return and which is vent and which fitting on the VST forward or rearward gets vent (or does it matter).
Any help would be appreciated ...thanks