Durango318
Seaman
- Joined
- Jun 12, 2010
- Messages
- 68
I'm wondering if it's because of our wonderful California fuel or something else? I have two MPI 7.5L (350ci) 330 hp engines in my re-powered houseboat. I've gone through four high pressure pumps (2 per engine). They lasted an average of 50 hours each. The first three were replace during warranty-no questions asked. BEFORE the engines were installed, the aluminum tanks were cleaned, new 1/2" uscg ethanol rated lines, new shut off valves, new 100 micron mesh high flow filters to protect the new 1/2" anti siphon valves (near/at tank top), then the Racor 660R-RAC-02 , 90 GPH 10 Micron water separating filters with Racor telltail vacuum gauges.
The gauges have never shown history of vacuum over 4 inHG. Periodically, I pull a few ounces of fuel from the separator bowls and it shows only a trace of water. The fuel is always treated with Startron stabilizer, not that the fuel sits tool long before being used. Both Racor and G-force filters are pe filled with fuel when changed and fuel rails bled with ignition cycled a few time. The fuel has been checked for phase separation,nada.
The G-force is a return-less system. The engine has two pumps attached. The first is the lift pump that is fed from the transom mounted Racor. It is a actually a Carter P4594 Electric with copper cooling tubes wrapped around it. Then the fuel is fed to the high pressure G-force unit. The G-force in a basically a submerged pump that is surrounded by a large water separating pleated filter element. Both are in a housing that has a water cooling cavity at it's bottom. There are three fittings at the top sides, inlet, outlet and return. The outlet has a check valve. The pump at the core looks like a dead ringer of a supply pump for Ford 6.0L Powerstroke Diesel and that's what I replaced it with and presently working fine.
I'm not a fan of return less systems as any air trapped or degassed fuel in the system keeps being recirculated in the system until it eventually exits through an injector. In the mean time it can cavitate pumps, slam closed dry injectors or or a lean shot. Yet many marine manufactures use it.
I'm about to convert it to a return system.
I understand the added complexity/safety issue of a return system: The fuel still needs to be cooled or it would heat the fuel tank, since it doesn't have air circulation as a car would. A new hole and leak proof fitting would be needed on top of the tank (fished through from the sender hole). The return line needs to terminate near the bottom of tank preferably not to close to the pickup. A check valve at tank return to eliminate siphone danger. A high quality return line. And more valves if I want to select tanks to draw & return.
Any input/comments or something I overlooked guys?
The gauges have never shown history of vacuum over 4 inHG. Periodically, I pull a few ounces of fuel from the separator bowls and it shows only a trace of water. The fuel is always treated with Startron stabilizer, not that the fuel sits tool long before being used. Both Racor and G-force filters are pe filled with fuel when changed and fuel rails bled with ignition cycled a few time. The fuel has been checked for phase separation,nada.
The G-force is a return-less system. The engine has two pumps attached. The first is the lift pump that is fed from the transom mounted Racor. It is a actually a Carter P4594 Electric with copper cooling tubes wrapped around it. Then the fuel is fed to the high pressure G-force unit. The G-force in a basically a submerged pump that is surrounded by a large water separating pleated filter element. Both are in a housing that has a water cooling cavity at it's bottom. There are three fittings at the top sides, inlet, outlet and return. The outlet has a check valve. The pump at the core looks like a dead ringer of a supply pump for Ford 6.0L Powerstroke Diesel and that's what I replaced it with and presently working fine.
I'm not a fan of return less systems as any air trapped or degassed fuel in the system keeps being recirculated in the system until it eventually exits through an injector. In the mean time it can cavitate pumps, slam closed dry injectors or or a lean shot. Yet many marine manufactures use it.
I'm about to convert it to a return system.
I understand the added complexity/safety issue of a return system: The fuel still needs to be cooled or it would heat the fuel tank, since it doesn't have air circulation as a car would. A new hole and leak proof fitting would be needed on top of the tank (fished through from the sender hole). The return line needs to terminate near the bottom of tank preferably not to close to the pickup. A check valve at tank return to eliminate siphone danger. A high quality return line. And more valves if I want to select tanks to draw & return.
Any input/comments or something I overlooked guys?