Engine cuts out when I increase speed from no wake zone

[keeper seeker]

Last fall I purchased a 1990 Seafarer that was repowered in 2004 with a 5.0L Mercruiser and Alpha 1 outdrive. Early this seson I filled fuel tank and put in sufficient additives. Initially I was having problems with moisture in fuel, and that has been elliminated. I used over 1/2 the fuel in tank and now boat runs well in the river 5-8MPH. Once I reach the open water and increase acceleration over 10 MPH it cuts out. I have been to the Mercruiser dealer they suggested Replacing Mercruiser brand fuel/water seperator with Racor, installing a new anti-syphon vale. I also put in an in-line metal fuel filter. Thought I was golden until I went to open waters and same thing happens. I tied up to a mooring, started engine, reved it up in neutral, and put hand over carburator severl times, and it seems to clear problem. Emptied fuel filter when I returned to dock, and fuel appears clear with a few small black particles. It has a electric fuel pump, and an aluminum fuel tank. I think there is junk in bottom of tank.
I am retired and I just bought this boat for enjoyment, but I am very frustrated and concerned about saftey. Any suggestions as to what could be next steps

 

[seasick]

Could be a few things: Bad gas in carb ( cleaning the tank won't clean the carb but usually you have issues starting)
Fuel restriction: Blocked or partially blocked vent, bad fuel pump, bad fuel line, bad siphon valve, etc. If there is a partial blockage, the motor will die and shutter as you speed up but may run fine if you back off the throttle. Does yours stutter, die completely etc?
Finally in the fuel department, there could be clogged jets in the card. The idle jets may be clear but the main jets if blocked will limit fuel as you open up the motor.
One way to check fuel flow is to TEMPORARILY install a clear fuel filter so that you can see the fuel flow. A pressure gauge tee'd in is better but the clear fuel may tell you if flow is restricted. Note that even when working correctly, the fuel filter may not completely fill with gas.

 

[keeper seeker]

Thanks for the suggestions. When the motor quits it sputters then I try giving it gas , then it konks out completely.

 

[seasick]

Generally if the motor sputters afte running at a set throttle for a period of time, the problem is fuel starvation.
If the motor sputters when the throttle is advanced from slow idle to mid speed, it is usually a carb issue like a dirty jet.

When it sputters, if you reduce the throttle does it run OK?

 

[30marlin]

Don't know the merc system to well but I have ran my last boat for 20 years with an OMC King Cobra.

It was a real nightmare when it was new. The shift system was never set up correctly from the factory when new and the dealer was completely clueless.

When I would try to throttle up to get on plane the shift cable would push just a little harder on the lever causing the shift interrupter switch to open.
This makes the engine cut out and it would spit and sputter and backfire.
Once that got straighten out it began to loose power until it would not run over 2000 rpm. Let it sit for 10 minutes and it run for another 15 and the same thing.
There is a screen in the fuel tank pick up tube that was clogged solid with fiberglass strands. The dealer said I got a bad load of gas until I told him I bought the gas at his dock.


As long as it is not an electrical problem the fuel system must be checked.
The first thing that must be checked is fuel pressure. It should rise with an increase in the rpm's (mechanical pump) If it starts to drop off quickly then there is a restriction or the pump is bad.
Small black particulars could be from a deteriorated fuel hose.
There may be a date printed on the fuel hose. If it is the same year as the boat or ten years old you should replace it.

Good luck and let us know how you make out.

 

[keeper seeker]

Seasick,

On several times that it has happened I have managed to return to my slip at a very slow speed ( 5-7MPH). If I try to accelerate in stalls out. Its a very long return trip and I don't tend to do well with all the bouncing around. As a matter of fact I am green, sweaty and sea sick myself.
Perhaps I am not cut out for boating.

Thanks again

 

[seasick]

Seasick,

On several times that it has happened I have managed to return to my slip at a very slow speed ( 5-7MPH). If I try to accelerate in stalls out. Its a very long return trip and I don't tend to do well with all the bouncing around. As a matter of fact I am green, sweaty and sea sick myself.
Perhaps I am not cut out for boating.

Thanks again

30Marlin, thanks for that tip. I will add it to my "how did I forget to check that" list.


Keeper Secret,
I chose my name for good reason. I can get sea sick on an escalator and have often said while tossing about " Maybe I am not cut out for boating"
The good news is that I get older, I seem to get sick slower and I always check the seas before heading out. More than 2 feet and I stay inside the bay.

As to your problem. When the motor starts to act up, if you shut it down for a minute or two and then restart it, does it start right up and run OK for a while? If so, I again suspect fuel starvation issue somewhere.

 

[keeper seeker]

At this point I think I have done what I am capable of mechanically. When I replaced the one way valve on the tank I did not see a screen or filter, Perhaps it is on the tube that's actually in the tank? Can I get to that? Do I just check the vent that is on the side of the boat for dirt or blockage?
Does the carb need to be rebuilt to get particles out of big jets? Could I use compressed air?
I called the Mercruiser dealer and they can't see it until Jafter July 4th.

Is there anything I can do myself in the meantime like change the fuel and vent hoses?
This is all new to me. Am I suppose to be asking these kind of questions from a forum?

Thanks
Clueless in Massachusetts.

 

[seasick]

At this point I think I have done what I am capable of mechanically. When I replaced the one way valve on the tank I did not see a screen or filter, Perhaps it is on the tube that's actually in the tank? Can I get to that? Do I just check the vent that is on the side of the boat for dirt or blockage?
Does the carb need to be rebuilt to get particles out of big jets? Could I use compressed air?
I called the Mercruiser dealer and they can't see it until Jafter July 4th.

Is there anything I can do myself in the meantime like change the fuel and vent hoses?
This is all new to me. Am I suppose to be asking these kind of questions from a forum?

Thanks
Clueless in Massachusetts.

There is no screen on the anti-siphon valve. There may be a screen on the tank pickup but you may not be able to get to it.
You can't clean the carbs wit compressed air and they may or may not need to be rebuilt..
One other thing to check is the age of your fuel lines. It is not uncommon for older fuel lines to degrade inside and block fuel flow but finding the bad spot can be tough.
Finally, if the vent or vent line is blocked, the problem will go away if you run with the gas cap open. Just be careful.
Sorry I can't be of more help but a lot of these troubles are difficult to isolate.

 

[keeper seeker]

Thanks for all your feedback. I'll check out the hoses and vent tomorrow.

 

[keeper seeker]

I bought a 6" piece of marine grade fuel lie, and filled up a 5 gal gas can.
I ran fuel line from gas can diectly to fuel/water seperator. Ran boat down river, and out to open water. I let her cruise at 3500 rpm, slowed down and brought it up to 4000 rpm. The boat ran great. I stoped boat hooked up fuel line from gas tank in boat, and opened her up, within a few minuted she stalled. But the line from gan can again and she started right up without hesitation. My conclusion "failty fuel line or vent hose"

When I returned to dock I replaced fuel line, and picked some dead bugs out of vent hose. I went out fishing and the boat handled great!

Thanks to your input I am back on the water.

Have a safe July 4th![/b]

 

[keeper seeker]

Should have read 6Ft piece of hose.
Sorry

 

[seasick]

I bought a 6" piece of marine grade fuel lie, and filled up a 5 gal gas can.
I ran fuel line from gas can diectly to fuel/water seperator. Ran boat down river, and out to open water. I let her cruise at 3500 rpm, slowed down and brought it up to 4000 rpm. The boat ran great. I stoped boat hooked up fuel line from gas tank in boat, and opened her up, within a few minuted she stalled. But the line from gan can again and she started right up without hesitation. My conclusion "failty fuel line or vent hose"

When I returned to dock I replaced fuel line, and picked some dead bugs out of vent hose. I went out fishing and the boat handled great!

Thanks to your input I am back on the water.

Have a safe July 4th![/b]

That's great and just in time for the holiday.
Stay safe.

 

[30marlin]

Hey thats great. It feels good when find and fix a problem like that rather than paying someone to replace parts until the problem is fixed.