Strange ?Fuel Problem

[crimson tide]

I have a 1995 Tournament 190 with a Mercury 175 Black Max(carburated,2.5liter,6 cyl.)that has run well for years. I can drive it all over the Gulf for several hours, and it runs like a top until I turn into Pensacola pass for the twenty minute ride to my house. The engine then begins to run at various sputtering speeds as if I have some fuel problem. It may run better when I decrease the throttle from the return-to-the-pass setting. I have changed the fuel filter on the motor once and the fuel-water seperation filter repeatedly, but the same thing keeps recurring. I always use premium gas and look for pumps that are not labeled with ethanol. I have checked the fuel pickup tube for holes (none), and opened the gas cap to rule-out a vent problem when this occurs. I always refill the tank to full shortly after arrival. I have added fuel cleaner/water absorber. I have also aspirated some gasoline from below the pickup tube and saw no debris and only the tiniest drops of water. The boat did sit for several months prior to this problem, but has been run a fair amont since that time. Thoughts?
Thanks,
Alan

 

[gw204]

Try running it off of a spare 6 gallon tank connected directly to the engine. That will tell you if it's an engine or tank/line problem.

Does your primer bulb say nice and firm?

 

[Keepin' it Reel!]

May be the neutral safety switch starting to go. It cuts back 3 cylinders just before going into neutral to make less strain on lower unit. Mine went bad and would run fine then out of nowhere drop off WOT - only running on 3 cyl. thought it was a fuel problem too. unplug the wiring harness and see if it helps - if that works just replace.

 

[JUST-IN-TIME]

do the 5 basic checks first
SPARK
COMPRESSION
GOOD FUEL
GOOD BATTERY
LOWER UNIT LUBE (i always do this)

i bet gummed carbs and f.pump

so anybody want to wager?

 

[plymouthgrady]

fuel?

I'll go with spark for $500...

 

[JUST-IN-TIME]

Re: fuel?

I'll go with spark for $500...

you got spark
I say fueling issue

anybody else?

 

[Tuna Man]

I go with fuel, specifically gummed up carbs for $1000.

 

[JUST-IN-TIME]

I go with fuel, specifically gummed up carbs for $1000.

2 for fuel issue
1 for spark

ANYONE ELSE??????

 

[Banana River View]

Crimson.. It is obvious what your problem is ... Your boat does not want to return home...BRV

 

[Seahunter]

When is the last time you changed the fuel pump diaphragm? If you haven’t by now it’s long over due.

And by the way, bag the premium gas. That unit was designed to run on 87 octane. Anything more is just throwing money out the exhaust port

 

[Boats Rock]

My buddy had the same issue. I found a brass screen in the elbow of the pickup tube that was clogged. I found it by blowing air back to the tank from the fuel pump. There was a one way check valve and I bypassed it. then I found the screen.

 

[crimson tide]

Thanks for the replies. The pickup screens are clean. The fuel pump diaphragm has never been changed to my knowledge. I still don't understand why the problem only happens 4-5 hours into the run and not until I get in the pass.
Thanks

 

[Seahunter]

Sounds like your loading up with water over time. Are you running the oil filter type or a Racor type filter with the abiltiy to drain water from the bottom?

 

[crimson tide]

Seahunter,
That is an interesting question. Why do you ask? I was running the old "oil filter" type fuel-water seperator until this week when I changed to a Racor so that I could at least see if water was accumulating instead of blindly changing the filter every time the engine sputters.

 

[Seahunter]

Seahunter,
That is an interesting question. Why do you ask? I was running the old "oil filter" type fuel-water seperator until this week when I changed to a Racor so that I could at least see if water was accumulating instead of blindly changing the filter every time the engine sputters.

Been there, done that. :wink:

I had a similar issue on my first boat. It would run great most of the season and then take a long slow road south at the end of the season.

I never put two and two togheter until the day the motor died 7 miles offshore. Tried all the usal fuel problems and unscrewed the filter as an act of disperation and found it full of water.

I installed a Racor the next day and never looked back. I now check for water in the bowl before and after each trip