fuel pump failure

[Incantation]

Hi,

Curious about the fuel pump; does it simply die when it's done, or will the motor start to show signs of unhappiness prior to failure? I acquired a boat with a well maintained atomic 4; unsure whether i should rebuild it.

Thanks,
Inc

[Al Schober]

Well, with the mechanical pumps there are two failure modes. First, the diaphragm will leak letting fuel into the boat or into the oil sump. Second, the pump will pump poorly or not at all due to failure or blockage of the valves.
In the first case, the engine will continue to run fine (until it blows up?). In the second (based on automotive experience) the engine may show signs of loss of power, finally running only at idle or a low speed.
With an electric pump, the valves are very similar to the mechanical. The diaphragm can also fail, but I don't know where the fuel would go. The internal switches can also fail, leading to complete failure of the pump.
With either pump, it's a good idea to carry a spare. Rebuild kits are available for the mechanical pump - not sure about the electrical.

Al

[ndutton]

I'd like to add to two things Al said:

First, by design and USCG regs, failure of the mechanical pump diaphragm expels fuel into the crankcase rather than into the bilge for safety reasons. Second, the electric fuel pump is robust but once it fails, it's done, not repairable.

Inc, I like the way you think (boat new to me, should I rebuild the fuel pump on principle?). I would and further, I'd begin a schedule of doing the same with other engine systems. You said the engine was well maintained but how do you really know? When was the fuel pump last renewed? Or the carburetor rebuilt, the oil changed or the impeller replaced? It's part of making your boat your own.

Don Moyer's latest newsletter is a good place to start, found here

[gary gerber]

First, do you have a mechanical pump or an electric pump? There are a number of factors that can cause a mechanical pump to "fail". Some checks to make: 1. basically, a clogged fuel delivery line 2. Remove the fuel bowl from the mechanical pump check for sediment fouling 3. ruptured diaphragm - not pumping ( If you disconnect the fuel line from the pump to the carb place a collection bottle at the carb end of the line and hand prime the pump by working the priming lever under the pump look for fuel discharge)

If access to your pump is very cramped and you remove the mechanical pump, a tip for remounting is to use allen head cap screws instead of the original hex head bolts. You can capture the cap screws in an allen wrench which makes remounting much easier since most of us only have two hands.

[joe_db]

A fuel pressure gauge is a good tool to see what is going on.