Engine cuts out above idle

[Beefer]

Ok, got the new to me boat in the water today, and had some issues (see http://forums.iboats.com/showthread.php?t=419701 for details). the one that's really bugging me is that the engine was cutting out at speed. I couldn't get up on plane, but I attribute that to the additional water in the stern (again, see other post). I was able to run at idle all the way to my final destination without incident, but when I gave it throttle, it would die about 30 seconds - 1 minute later. Restarting was a bit troublesome. It sounded like it was out of gas, but it would start, but die at high idle. Backfired a couple of times as well.

Some of the thoughts I'm having are; water in the fuel system, needs new spark plugs (tune up), or I damaged something with the near sinking. It the beloved Mercruiser 488 (170), with the Alpha I Gen I outdrive. It has a fuel water separator, but I couldn't tell in the dark whether fuel or water was coming out of the petcock, although it smelled like gas, but felt like water. The boat sat for about a year, and PO used E10 with Sta-Bil. There were approx 20 gals of the old gas, and I added 20 gals before leaving. Any ideas?

 

[achris]

Re: Engine cuts out above idle

With that much water in the boat (I assume salt water) the engine flywheel and front pulley would have been throwing the stuff everywhere. You need to dry out all the electrical and ignition systems, and clean the salt off them.... Then start looking to see if the problem is fuel or ignition....

Chris........

 

[Beefer]

Re: Engine cuts out above idle

Took her out today, and still cutting out and losing power. The backfiring is not happening like it was the other day. I ran her around for about an hour in the channel, and after about 3/4 mile, the speed would drop from 28mph to 11mph (GPS), at which point I would drop her to idle, and everything would go back to sounding normal. Getting some 'chugging' at the higher speeds/rpms like it's running out of gas. The backfiring that did occur (twice) happened early, at at the carb. At least I was able to get up on plane, just not for very long.

I don't think the water issue the other day had much to do with this, but not sure. I did rinse off the externals, and wipe them down, hoping to remove any salt residue, and I think I was successful.

Oil and coolant levels are good, temp was between 130-150, oil pressure was in the normal range.

I did add some gumout fuel system cleaner the other day, and I'm thinking it helped. I haven't done anything with the spark plugs/cap/rotor, etc.

I'm thinking either; fuel, fuel filter, water separator filter, fuel pump, or carb. I'd like to start with the fuel, but draining the tank is difficult, as I have no where to put 40+ gallons of fuel. Could I try to siphon primarily water from the tank by getting the hose to the lowest point of the tank? I'm thinking if there is water, and I can get most of it out that way, I could run it and let the separator do its thing, and I monitor it, changing/emptying every so often. Any other ideas on this?

Thanks!

 

[6meter]

Re: Engine cuts out above idle

Hook up a hose to a gas can and the fuel pump with new gas in it. Same problem comes up, its not the gas.

 

[chaparall villain 2]

Re: Engine cuts out above idle

i would also check the points and condensor and replace them .. they can cause similar symptoms to a fuel problem