Boat runs great in Driveway, but stalls on water

[mrtommy03]

Re: Boat runs great in Driveway, but stalls on water

If you keep randomly replacing parts long enough, it's possible that you'll sooner or later get to what's wrong.

Logically troubleshooting the problem usually gets it fixed a lot quicker and cheaper ......

Did you even look at the link I posted above, in the earlier post?

Understood...I'm not "randomly" replacing these parts...I had a mechanic friend look at these things and he suggested to replace them. I did look at the link you sent me (See my comments)...

1. Fuel condition. Type and Octane possibly old fuel - We drained and refilled the tank. I only put 93 Octane in the tank
2. Propeller pitch or diameter, damaged blades - Checked...this is all good
3. Restricted fuel pickup tube or anti siphon valve Fuel System Test
4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse - This is good
5. Marine growth on hull and outdrive - No growth...hull and outdrive are clean as a whistle
6. Wrong gear ratio in outdrive - No idea how to check this
7. Restricted carburetor air intake (clogged flame arrestor) - I've already cleaned the flame arrestor...It's sparkling clean
8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive - Not sure how to check
9. Poor cylinder compression Compression Test - Performed the test...All is good...numbers were between 110 and 120
10. Carburetor defective, or wrong type. - It's been rebuilt...all looks good there
11. Fuel pump pressure and vacuum - I've had a brand new fuel pump installed
12. Boat overloaded, improperly loaded, or improperly trimmed. - what does improperly trimmed mean? I lower the trim when I get in the water
13. Engine Overheating - Not a problem
14. Engine timing and ignition system operation - Gonna check this the next time I get on the water
15. Remote control cables and linkage for proper travel to open throttle plates fully - These all seem to be fine, but how can I make sure?

 

[Provo5]

Re: Boat runs great in Driveway, but stalls on water

After I rebuilt my carb I had to adjust it with the boat in the lake. Until I did that it did almost the same thing.

 

[mrtommy03]

Re: Boat runs great in Driveway, but stalls on water

After I rebuilt my carb I had to adjust it with the boat in the lake. Until I did that it did almost the same thing.

How and what exactly do you adjust? Adjust the carb? What do you adjust while on the lake, and how exactly do you do it?

 

[bruceb58]

Re: Boat runs great in Driveway, but stalls on water

I would like to know that too! You can adjust idle jets but that doesn't appear to be the OPs problem.

What I would like to know is what is the history of this boat. Has it ever run right? What prompted the two carb rebuilds?

 

[45Auto]

Re: Boat runs great in Driveway, but stalls on water

An engine that runs great in neutral (no load), but doesn't develop power under load is many times a sign of fuel supply problems. I would suspect the carbureter rebuilds (incorrectly done) or a problem with the fuel delivery system. I was troubleshooting a boat with a 260 Mercruiser yesterday for almost the exact same problem. Wouldn't turn over 3000 RPM under load. Turned out that whoever rebuilt the carb had put the inlet filter in backwards so the closed end was blocking the fuel flow.

Is your accelerator pump working at all? Can you see it squirt gas into the carb if you look in the carb (engine off) while someone works the throttle?

 

[Knightgang]

Re: Boat runs great in Driveway, but stalls on water

I also disagree that it isn't a carb issue. You could have a very lean condition and still rev it in neutral.

I have hed this happen to me, so I know it can run great in a driveway and still have carb issues on the water....

 

[gdombroski]

Re: Boat runs great in Driveway, but stalls on water

3. Restricted fuel pickup tube or anti siphon valve Fuel System Test

You didn't have any comment on this check point. Either of which will cause similair problems under load. I would first pull the anti siphon valve and check it for gunk.

 

[WIMUSKY]

Re: Boat runs great in Driveway, but stalls on water

Had the same problem this year. Turned out to be a plugged carb fuel filter. Check, replace or clean your filters. Even tho the carb was rebuilt, there still could be crud in the fuel lines. If you see any hint of black specs in the filter you may want to replace your fuel hose too. It could be breaking down and/or collapasing when it calls for more fuel thus restricting the flow.

 

[Fireman431]

Re: Boat runs great in Driveway, but stalls on water

Just a couple more thoughts:

1) Sounds like a fuel delivery problem. Clogged pick-up tube, old fuel line (just replace all of it. It's cheap), clogged fuel filter, filter install improperly.

2) Never do a compression test with the coil wire removed. Simply remove the kill switch lanyard. Why would anyone want random sparks in their engine area?

 

[dieselboy86]

Re: Boat runs great in Driveway, but stalls on water

I know its been said already that the carb has been rebuilt twice and they were new rebuilt carbs. I had the same problem with my boat this summer and i just threw money at the problem. I finally got fed up with it and had my mechanic look at it and eventhough it was a new carb the accelerator pump was bad. I put a new pump in and it helped but still not totaly. come to find out it was the float out of ajustment. Ajusted the float and bada bing it ran like a raped ape. if it helps your welcome if not it was just 2 cents

 

[Lou C]

Re: Boat runs great in Driveway, but stalls on water

You didn't have any comment on this check point. Either of which will cause similair problems under load. I would first pull the anti siphon valve and check it for gunk.

I had the exact same problem on my '88 4.3 OMC...it started and ran well...would rev to 3000 in neutral in the water ( did this to check the total spark advance with the advance timing light which was right on) but fall on it's face anytime there was a load placed on it...since I was out of ideas I took it to the mechanic and turned out it was the anti siphon valve...and the carb had a bit of water in it so he rebuilt the carb...that was back in 2004 and it's been fine ever since...

So look at the anti siphon valve (right angle fitting on the gas tank that the fuel line from the pump attaches to.....my mechanic explained that sometimes they use a cheap aluminum one that corrodes internally. The fuel pump has to suck the fuel through antisiphon valve and against spring pressure (the valve closes when there is no vaccum against it to prevent fuel leaks in the bilge if that fuel line ever leaks...)

 

[full stringer]

Re: Boat runs great in Driveway, but stalls on water

had an issue with a omc 5.7 the float adjustments were off and under load not enough fuel was being delivered hopefully they used marine components when rebuilding and adjusted to marine specs

 

[1216bandit]

Re: Boat runs great in Driveway, but stalls on water

you could try running with an auxiliary tank. I had a similar problem and when I hooked up the aux. tank all was good. I replaced the anti siphon valve to solve the problem.

 

[kkukowski]

Did OP ever get this resolved? I have the same problem on a 1987 Ford 2.3 OMC - what was the fix?

 

[GA_Boater]

Did OP ever get this resolved? I have the same problem on a 1987 Ford 2.3 OMC - what was the fix?

The fix is starting a thread of your own. How does anyone know if the OP fixed it since he never told.

Closed,