Fuel pressure loss on Mercruiser 140

[boozer1966]

I pulled the pickup out of the tank. Sealed up the bottom end put a short piece of hose on the barb end. Then put under water with air hose to pressurize. No leaks. Figured I’d start there and work my way back. Checked and rechecked all hose ends and connections. The PO had the pickup barb pointed towards the bow which made the hose take a round about way back to the engine. I moved it about 90 degrees for a straighter shot. Then blew out the fuel line from tank to pump. Engine started right up with fuel pressure at 3 psi. Ran fine. Then acted like it burped. Fuel pressure went to 6psi and stayed there through a few cycles.

 

[boozer1966]

Mechanical fuel pump should run at about 6 psi?

 

[achris]

Mechanical fuel pump should run at about 6 psi?

Yes.

 

[boozer1966]

UPDATE: I feel like an idiot. Took the boat out yesterday and still had the same problem. Today, I took the fuel gauge sending unit out. I had taken it out a few years ago to fix a leaky gasket and I used plain old RTV to make a new gasket. RTV is apparently NOT impervious to gasoline. It has essentially decomposed and was dripping into the gas tank. That was problem one. Problem two was the fuel pickup. I took the top piece off to discover a small metal screen in it. Picture below. It was almost totally clogged. Any comments on whether or not this is even necessary?

Hope this helps someone else avoid my stupid mistakes.

 

[Scott Danforth]

many threads about pulling that screen.

if you have a good filter before the fuel pump, that screen is not needed.

 

[Dubed]

many threads about pulling that screen.

if you have a good filter before the fuel pump, that screen is not needed.

Of course, that filter will also need to be maintained.