Engine floods or dies when making hard turns to left

[Cory haupt]

We noticed this last weekend but thought it was a fluke. We just had the boat in the water for 5 hours today and 3 times while making hard left turns the left motor died and acted like it flooded out. Changed the plugs before going out and this happened for the first time today after 3 hours. Thinking possibility that fuel is being pushed to hard away from pump but any help would be appreciated. The boat runs strong any other time just during the sharp turns is when the issue arises.

 

[hivoltage98]

We noticed this last weekend but thought it was a fluke. We just had the boat in the water for 5 hours today and 3 times while making hard left turns the left motor died and acted like it flooded out. Changed the plugs before going out and this happened for the first time today after 3 hours. Thinking possibility that fuel is being pushed to hard away from pump but any help would be appreciated. The boat runs strong any other time just during the sharp turns is when the issue arises.

What engine type in the boat?

 

[Cory haupt]

Twin bombardier 787s

 

[hivoltage98]

It might have something to do with the accelerator cables for when you turn. When you turn to the extreme left or right it pulls the carbs open to accelerate the engine to help turn. Only one engine would do it though.

 

[Cory haupt]

That could make sense. Since you mentioned the cable I didn't know what the control system actually did until after I just looked it up. Our control system doesn't work. When we make hard left and right turns the throttle does not increase on either motor. So I am guessing that the control system is not working at all

 

[riffe723]

That could make sense. Since you mentioned the cable I didn't know what the control system actually did until after I just looked it up. Our control system doesn't work. When we make hard left and right turns the throttle does not increase on either motor. So I am guessing that the control system is not working at all

I’m having a similar issue, however mine only revs when I turn left. The control system does not work when I lock to the right. And coincidentally my right motor does flood similarly to yours, but only sometimes.

 

[hivoltage98]

It’s only active when you at idle it will work. So when your coming into dock it will bump up the rpm’s up to give you thrust. But if the cable is messed up it might be pulling your carbs back down. Just a guess.

 

[Cory haupt]

This doesn't happen at idle though. We banked it twice over the weekend while pulling a tube and it flooded the engine and the second time it happened without pulling a tube. I have read that it could be fuel sloshing away from pump but we had half a tank left and it was only the right motor that flooded. We are taking the boat out again tomorrow evening and I will see if the control steering works while at idle or not.

 

[hivoltage98]

Good luck, keep us updated on what it is.

 

[2x2smoke]

If the problem is seen in both engines, it might be fuel starvation from the fuel tank or baffle. That would be the opposite of "flooding".

Before going out again, I would pull the baffle out to inspect the pickup tubes and all the hose connections. Write down the baffle part number. Find out if both pickup tubes are intact, unclogged and the same length and if not which engine is fed by the shorter pickup tube. At the same time siphon fuel off the very bottom of the tank to make sure there isnt a thick layer of water sloshing around down there.

If everything checks out ok with the tank and baffle, I'd have all my tools and a diagnostic plan ready before I took it out on the water tonight.

 

[Cory haupt]

I’m having a similar issue, however mine only revs when I turn left. The control system does not work when I lock to the right. And coincidentally my right motor does flood similarly to yours, but only sometimes.

Mine is only sometimes too but seams to be when I am making a 360 degree turn hard

 

[mikidymac]

If low on fuel the pickup in the tank could be sucking air on hard turns.

 

[Cory haupt]

Ok so this past week I took more steps to try to eliminate the problem. I replaced fuel filters thinking maybe water. The filters were dirty. Yesterday took the boat out and since there were alot of boats the water was really choppy. Engine cut out but this time trying to get to the bottom of the issue paying close attention. I noticed that during the hard turns in choppy wavy water the jet starts to cavitate inturn 2 to 3 times and the left engine dies.

So could this be due to cavitation of left motor?
Could the engine be over rev prevention and killing motor?
Does these boats come equipped with a rev protection?
Is there any way to eliminate this from happening?

All ports are free of debris and runs great like a jaguar on straight water with no hesitation or cutting out

 

[mikidymac]

No, the cavitation will not kill the engine or rev limiter.

 

[Cory haupt]

I'm trying to figure it out. I just know it cavitated and could hear the engine reving at the same time

 

[bkwashby]

The centrifugal force caused by the hard turn pulls the fuel against the suction in the carbs resulting in less mixture getting into the engine causing it to stall.

 

[Cory haupt]

If this is the case. Is there a way to fix

 

[bkwashby]

It's a manufacturer defect so as far as I know there is no fix other then to take your hard turns to the right instead or no hard turns at all.

 

[Cory haupt]

Interesting I just found an article on the turn left syndrome.


PERFORMANCE TIPS
The "Left Turn Syndrome"
You will find in all instances that your watercraft will turn more easily to the right than to the left. The reasons are basically simple. First, engine torque constantly places pressure on the hull to turn right. If your engine's performance is marginal, you can notice a dramatic fall-off in power in a hard turn. This power fall-off can't always be blamed on the engine, being over-propped can also cause the engine to slow enough to fall off its power peak. An engine with a peaky power curve is especially susceptible to a very dramatic power loss in a hard left turn. Most recently, with the increase of Sport and Runabout racing, there has been a marked improvement in hull design with a dramatic increase in "G" forces encountered while turning: over 2.5 G's. In some instances such a hard turn can cause momentary loss of power due to fuel starvation in the carbs. Jetting changes cannot correct this situation, the best solution is to rotate the mounting of the carbs 90 deg, so that their throttle shafts are perpendicular to the crankshaft axis rather that parallel. To date, this solution to the problem has been 100% successfu

 

[Sportster-2001-951C-Stock]

If the issue is fuel starvation while the fuel tank is mostly full (not sloshing from the pickup) then you may have a weak fuel pump.

There were two fuel pump setups on the older twin boats, the one that was marginal used a fuel pump that's divorced from the carburetor. The system that has the fuel pump integrated with the carburetor didn't suffer from fuel starvation issues, in general.

The old divorced type of pumps would wear out and just couldn't keep up with demand.

The rev limiter only limits upper RPM (by shunting spark ignition at high revs), it's not responsible for an engine to quit running.

Some of the ski engines (1st revision of 951 painted white only?) had the carb butterfly shafts in the horizontal orientation with the fuel metering chamber on top and this was cause for some fuel metering issues. They fixed this issue with the silver painted engines as they rotated the carbs to orient the butterfly shafts vertically with the fuel metering chamber on the side.

I suggest trying to determine if the problem is over fueling or fuel starvation then go from there but if you have the divorced fuel pumps then probably one (soon both) is worn out. There's a next size up replacement pump that works well in this case.