Can a fouled prop cause engine problems?

[cfergu22]

Question....

Is running the engine with a fouled prop bad for the engine?

Background...

Because of Kids and work schedules we haven't been able to used the boat more than once or twice a month. We're at a marina in Baltimore and our prop becomes fouled very quickly, sometimes within a few weeks after we have a diver clean it. Because of that we often used the boat when the prop is fouled. We usually only need to motor a few hundred yards out of the marina so a loss in speed isn't a big deal.

But a few weeks ago, we got on an overnight trip and had to motor for about 3 hours. We were definitely pushing the engine hard just to get to about 4.5 knots. Normally we coast right along at about have throttle to get to 5 knots. We don't have a tach so I don't know the RPM we were running at.
Right before we came into the dock the engine died. After a whole bunch of troubleshooting, it turns out it was just a inline fuse between the alternator and the fuel pump. That fuse has been there since we bought the boat and has never popped before. Then when we were coming home, we ran out of gas and it took us forever to get the engine to start up again. Much longer than any other time we've run out of gas. I still don't know what the problem was but it's running fine now.

I'm going to get that fuel pressure gauge, It would have drastically reduced the troubleshooting time the first day.

So could the fouled prop and pushing the engine to hard have caused the fuel pump fuse to pop after a few hours of running? Is there any other damage that can be done to the engine by running it like that? Basically I'm wondering if we have to start getting our hull cleaned more often before we destroy the engine.


As a side note for other people trouble shooting an engine that starts but only runs for a minute before shutting off... The reason it took us so long to trouble shoot, is because I normally "hot wire" the fuel pump to test to see if it's working. When I did that it was pumping fuel. So I ruled out a fuel delivery problem. I was stupidly bypassing the fuse when I was doing my test. We'd get the engine to start, then it would shut off within a minute. Basically, the ignition switch was pumping a little fuel in, because that bypasses the fuse and the OPSS.
But when the engine was running normally there was no power to the fuel pump.

[Dave Neptune]

No a fouled prop won't hurt the engine. All the fouling does is increase the load on the engine to attain the same speed and due to the inefficiency of the fouled prop and hull you will loose speed.

Get that F/P gage mounted before throwing parts and money at the problem. Could be as simple as a clogged filter which could yield good fuel pressure at idle and a drop in pressure when throttled up causing a lack of fuel and or stalling.

As far as blowing the fuse the load on the prop, engine. and the fuel pump should not blow a fuse. Perhaps you shorted it while doing a hot wire or you have a voltage issue.

Dave Neptune

[cfergu22]

Thanks for the reply

Does Moyer sell a Fuel Pressure gauge? I can't find one on their sight. If not, what is the most simple way to set one up. I don't need to see it from the cockpit. I figured i'd just mount it right next to the carb.

[Sam]

Multiple brands available on ebay. I like my "Marshall" 0-15psi, stainless body, glass lens, liquid filled [more steadier reading]] - about $20. It goes between pump and carb - you need to get an adaptor that goes on to the lines and the gauge screws into the adaptor.

[cfergu22]

Thanks, That looks like it would work out perfectly, and would be pretty easy to install.

[sastanley]

The one Sam recommended is fine..I have the Mr. Gasket 1561 from Amazon. A 3 way tee with 1/8" NPT threads will screw into the gauge, and then a couple nipples for the fuel hose.

[JOHN COOKSON]

This would be an excellent time to add a "polishing filter" if you don't have one already.

ex TRUE GRIT