engine stalling after warming up

I am looking for advice as to why my boat will idle poorly after warming up. in fact, it will sometimes stall at the dock as I come in from a full day of riding (which sucks when I hit the dock). It has reached a point of feeling flooded when I give it full gas during takeoff. any advice would be greatly appreciated.

Boat info
88 prostar w/454 option and Holley 750 cfm that was just rebuilt.

carb running rich?

bad gas?

someone else would have better ideas....

What is your idea of "feeling flooded"? How does it stall? A quick stall or a longer drug out stall? Can you pump the throttle and keep it running? What happens when you whack the throttle WFO fast? How does it restart? Do you pump the throttle to restart it? What happens if you do pump the throttle when hot, before starting? What color are the spark plugs? Has it back fired through the carb possibly taking out the power valve? Do you see any black smoke coming out of the exhaust? How does the engine run if you crack the throttle?

Accurately answer as many of the question as possible, then we can help lead you in a direction.

It sounds like a problem I had with my 1991 Prostar. It could be a number of things. Here is what comes to mind first...

1. Float sticking after the rebuild. after it cuts out look done the throat of the carb to see if gas is still going into the engine. Be careful and have an extinguisher handy in case.

2. Check your engine timing and adjust if necessary.

3. throttle linkage was not put on properly.

4. check the gas filters (2) to see if any water or dirt is causing problems.

These are a few easy things to check first. If it's not one of these then more than likely the carb is the issue. I assume you did not have these problems before the rebuild

(Message edited by byrd on September 16, 2006)

1. A float sticking after rebuild would cause it to flood out and it would be hard to restart, requiring a lengthy cranking cycle or opening the throttle to clear flood mode WFO (Yes works even on a carb).

2. Timing can cause the problem. Did someone adjust it?

3. Throttle linkage should not matter one way or the other. In fact take it off, then put it back on to make sure it is going to closed throttle. If it is being stuck open, then it should idle higher. Simply make sure it closes the butterflys.

4. Fuel filters could cause the problem. A plugged filter would show up under a load, not right when returning to idle. A long idle time could cause a plugged filter to show it's evil head. Water can cause all kinds of problems, and will usually cause it to sputter and run like crap even under a load. So does it?

5. So why was the carb rebuilt?

6. Any other things done to the motor at the same time, like timing adjustment, tune-up etc.?

7. Did you adjust the carb with the boat in the water in gear? Usually you need to balance the in gear and out of gear to get it just right. Rap the throttle and see how it returns to idle. If it goes below idle speed it is too rich. If it immediately stalls it is too lean. Assuming base idle is a the correct RPM.

Thanks for the advice so far. The reason I had the carb rebuilt was because of a slight hesitation while coming out of the hole. I noticed that the fuel filter being dirty came up a couple of times. Would this cause to boat to run fine when cold then poorly after warming up? Anyway I'll change it (there are two of them?). As for the timing, it was not touched however I did change the plugs, cap, rotor, points, condenser, etc. Perhaps the distributor moved while doing this.

When I describe it as "felling flooded" I mean that if I fully open the throttle, the boat doesn't have any pop, it has a hesitation or surging feeling and will not reach full speed.

On my PS 190 there were two filters. Since you did change the plugs, cap, etc. I would start with the timing and filters.

Check the cap for moisture. It would run great right out of the gun then poorly or not at all after you try to restart it. Condensation might be forming inside the distibuter cap. Wipe it out with a dry rag and you're back in business.

If you changed the points, the timing changed and needs to be checked. I wouldn't expect the timing to have changed enough to cause this sort of problem, however.

Check to see if your boat has a PCV (pollution control valve). This is usually a small plastic device on the valve cover that has a 5/8" hose that leads to the base of the carburetor. When these things go bad they will create a vacuum leak that can result in these exact symptoms. A quick test would be to pull the hose off the carb and plug the hole at the carburetor base.