EH700 Fuel Pump??-gctid344384

[Guest]

I have a '86 38 with 175 hinos. A while back we made a 14 hour run from the fl keys. The last mile or so home is in idle speed canals. A couple of hundred yards from the dock, the port engine quit. Docked, unloaded and went to bed. A couple of days later, try to start the engine and nogo. Pumped the primer pump at length; engine started and ran fine at 1k rpm. Shut it off. Couple of weeks late exact same sequence of events - no start; prime; start. This time when priming i felt fuel around the primer pump plumger. I ran the engine at 1k rpm for 15 minutes and no problem. Backed it to idle and in 3 minutes it quit - kinda like it did coming home previously. I'm suspecting the lift/feed pump may have an air leak possibly around the primer pump. Anyone had experience with the pump?I'm considering swapping the whole pump between engines. Thoughts would be appreciated.

Mike

[Arizona_Bob]

HI MIKE,

I have had this happen to me on my 3888. Sounds to me like you have air leaking into the fuel system. This leak can come from the pressure side as well and the return side of the fuel system. Check all the fuel line fittings and clamps to make sure they are tight also check the fittings on top of the fuel filtters. The filter top plug had a O'ring leaking air and was causing my problem and sense it was on the suction side it did not leak any fuel out. Another way to check is to put a clear plastic hose in the return fuel line and check for any air bubbles in the clear hose. There should not be anything but clear fuel in line no bubbles. Hope this will help you find the air leak in your fuel system.

BOB

[jmcannonball]

In addition to the above suggestion and before switching fuel pumps you might want to try some of the easier choices:

1. Check all the hose clamps in the fuel supply line from the port tank to engine to insure they are securely tightened. Check for brittle/cracked line. Check BOTH O-rings in the fuel filter/water separator - the large one under the lid and the small one under the T-handle (or vacuum gauge if so equipped).

2. Switch the fuel manifold so that the port engine runs off the starboard tank (don't forget to switch the return line also). If the engine does not stall out, then the problem would be between the manifold and the tank. You should check the pickup tube in the port tank to see if it is clogged. If the engine dies then there is possibly an air leak somewhere between the manifold and the fuel pump.

3. After using the priming pump, be sure to screw it down securely.

Let us know what you find.

[Guest]

Thanks for the input. I hope to get on the problem this weekend. Some few years ago, I replaced the dahl filters with racors and re plumbed the whole fuel valving system. As a result he racors are mounted above the fuel level in the tanks. Every couple of years the check valve seats in the racors start leaking causing the fuel to drain from the filters back into the tank overnight. There seems to be just enough fuel in the engine to get away from the dock before an engine quits. Embarrassing!! As a result, I replace the check valves every 2 years and most time shut off the tank valve when not underway.

I'll report what I find.

Mike