Occasional power loss under way

[cruzin1a]

Hi guys. I thought I would bounce this off the group. Today was our third run on the boat. We just bought it this spring. It's powered by a 1988 5.7 Merc I/O 350. On the first two runs I got an occasional sputter while running at about 2800 rpm. Today on the third run the power would go away and it would knock a little. I was able to get it started after each time and it would run fine for awhile but then would do it again. As we neared the dock it became difficult to keep the idle up. When putting the boat from forward back to the neutral the idle was so low that the motor would stall.

The boat has a 60 gallon tank and was half full when we bought it. I have since added an additional 30 gallons. When I put the fuel in I added CRC Phaseguard 4 ethanol treatment. My question is, is the problem water in the gas? My first mission is to pour the contents of the water separator into a pan and inspect it. And then install a new one.

Any thoughts would be greatly appreciated.

 

[airshot]

Re: Occasional power loss under way

Changing the fuel/water filter seperator would be my first thing. If possible look into tank and see if water is in there (I can see into mine after removing a cover), add a fuel dryer or better yet pump out the tank and start with a fresh fill. Had a similiar thing happen last summer and that was my problem, good luck!!

Airshot

 

[cruzin1a]

Re: Occasional power loss under way

Thanks for the tips airshot. Can you recommend a good Fuel dryer? All I have been finding is Ethanol treatments. Also many folks have mentioned trying to siphon the water off the bottom of the gas tank. I can't lie, 30 or so gallons of gas scares me.

I'm glad to hear you resolved your issue and do appreciate the input

 

[BIGALF]

Re: Occasional power loss under way

Start looking at the fuel pick up tube that is in the tank. Is there a screen in it that will clog up when you run the engine in the water? My 5.7EFI Mercruiser did and it took me many tries before I was told about the screen. Took it out and it runs fine now. If not then go to the water seperator and any other screens in line to the engine.

 

[cruzin1a]

Re: Occasional power loss under way

I will take a look at the access to the tank some night this week to see if I can easily get to the fuel pick up tube. I know I do have access to the connections. We are going to very carefully attempt to drain the tank. I guess I can put the gas in my truck and use it that way instead of wasting 30 or so gallons of gas. Thanks agin for the tips!

 

[BIGALF]

Re: Occasional power loss under way

I had to drill a hole in my deck to get to the fuel pick up tube. You might want to fine the tube first before draining the tank. If you drain the tank and it still does the same problem you will have to get to the tube anyway.

 

[Bondo]

Re: Occasional power loss under way

We are going to very carefully attempt to drain the tank.

Ayuh,... No reason to Drain it...

If it's got Water in it,... It'll All be at the bottom...
Just suck out 5 or 10 gallons, 'n Inspect it...

If it's just Bad gas, 'n smells Rotten,...
Don't put it in yer truck, those motors are Way more complicated than most boat motors..
Pump it. 'n Dispose of the Rotten Smelly stuff...

 

[cruzin1a]

Re: Occasional power loss under way

Update, I removed and replaced the water/seperator filter. I poured it out in to a clear jar and found no water in the gas. I then added two cans of Seafoam in the hopes it will clean the fuel system, I know I've read the threads, I figured it was worth a shot. I also found that the boat was idling very low in neutral. I adjusted the seat on the carb so the dockside idle is now around 700rpm. Not quite sure why that was all of a sudden an issue. I do know the throttle cable looks tired and it is possibly the original. It's on my short list to be replaced. I took it for a run upriver. Not one backfire. There was not one instance of loss of power and the idle was perfect going in and out of gear. I think only time will if it was a little bad gas or possible something like a carb that needs to be serviced.