Engine surging after break

[REW]

The engine in my 2004 wakesetter (320hp mpi) surges after a break on the water. It will start but will surge up and down in RPM and occasionally die. During this time the exhause smells real bad like the fuel is not being mixed properly. This has only happened a few times, I thought fuel may have been the issue the only time it happened last year (marina gas) but I have run over 100g this month alone, it happened yesterday about 8 miles from the ramp.

Thanks in advance

REW

[68Slalom]

Sounds like it could be a bad throttle position sensor (TPS) starting to act up or a small vacuum leak that is created when the engine cycles from running temperature to warm, how long of a break are you talking about? Try checking all the bolts on your intake and throttle body, unplug any wire harness' and make sure there is no corrosion. 80% of major malfunctions are always electrical issues and it could be so simple as to a bad connection.

Edited June 26, 2009 by 68Slalom

[skier92]

Is the surging occuring with the throttle advanced or at idle? If @ idle, might be IAC (Idle Air Control) among other possible issues.

[Surfin247]

I have a 2005 V Ride which is very similar to the 2004 Wakesetter. I have had the same occurance if I stop for 15-20 mins. after running it hard or a long time. I believe you are experiencing heat soak/vapor lock. Easy way to tell is if you have the silver canister (fuel pump) on the front driverside of the engine, and it is hot to the touch then that is your problem. The engine heats up the fuel pump and vaporizes the fuel so the proper amount of fuel is not available at start up. This causes the surging. Solution is two part. One is to open the middle hatch when you stop for more than 10-15 mins.( this depends on outside temp. and sun exposure) to let the heat out. Second part is used if you forgot to do the first part. Put a damp/wet cold cloth on the fuel pump to cool it down before restarting engine when the surging and stalling occurs. Takes about 5 mins. and ice water works the quickest, but lake water will also do. This has worked for me every time I have had this problem. The other solutions stated above are also a possibility, but the TBS and IAC problems would occur most of the time not just when you ran and then sat. If the only time you are having this problem is when you run it and then sit to long then your problem is heat soak. Try cooling the fuel pump and see if it works. It is a lot easier and cheaper then messing with IAC and TBS. A good rule of thumb is to do the easiest/cheapest things first and work your way up. I believe Malibu went to having the fuel pump in the gas tank in their newer models for this reason.

[BillFooter]

+1 for vapor lock.

[REW]

I have a 2005 V Ride which is very similar to the 2004 Wakesetter. I have had the same occurance if I stop for 15-20 mins. after running it hard or a long time. I believe you are experiencing heat soak/vapor lock. Easy way to tell is if you have the silver canister (fuel pump) on the front driverside of the engine, and it is hot to the touch then that is your problem. The engine heats up the fuel pump and vaporizes the fuel so the proper amount of fuel is not available at start up. This causes the surging. Solution is two part. One is to open the middle hatch when you stop for more than 10-15 mins.( this depends on outside temp. and sun exposure) to let the heat out. Second part is used if you forgot to do the first part. Put a damp/wet cold cloth on the fuel pump to cool it down before restarting engine when the surging and stalling occurs. Takes about 5 mins. and ice water works the quickest, but lake water will also do. This has worked for me every time I have had this problem. The other solutions stated above are also a possibility, but the TBS and IAC problems would occur most of the time not just when you ran and then sat. If the only time you are having this problem is when you run it and then sit to long then your problem is heat soak. Try cooling the fuel pump and see if it works. It is a lot easier and cheaper then messing with IAC and TBS. A good rule of thumb is to do the easiest/cheapest things first and work your way up. I believe Malibu went to having the fuel pump in the gas tank in their newer models for this reason.

Thanks for all who replied I will check on what is happening the nest time it starts misbehavin. This sounds like the best answer it happens mostly on hot days and after a good workout with me or the kids. running the exhaust fan seemed to lesson the effects but I wasn't sure if it does or just makes me feel like I am doing something. I will try opening the motor box up during breaks.

Would insulating the pump help?

REW

[BillFooter]

Insulating the pump might help. You can pour a little water on the fuel pump (key in off position) to cool the pump. One of my buddies had an electric fuel pump installed between the engine fuel pump and tank and so far it has helped to keep his from vapor locking.

[REW]

Insulating the pump might help. You can pour a little water on the fuel pump (key in off position) to cool the pump. One of my buddies had an electric fuel pump installed between the engine fuel pump and tank and so far it has helped to keep his from vapor locking.

Anybody have an idea about moving the pump off the engine completely. I have some other wintertime porjects for the Bu and will be taking the tank out anyway.

[68Slalom]

+1 for vapor lock.

I don't think that vapor lock will effect the idle. IF you have vapor lock in my understanding you can't turn the engine over enough for it to start, water won't compress (excessive moisture in the cylinder/s do to fuel boiling)

Edited June 26, 2009 by 68Slalom

[REW]

+1 for vapor lock.

I don't think that vapor lock will effect the idle. IF you have vapor lock in my understanding you can't turn the engine over enough for it to start, water won't compress (excessive moisture in the cylinder/s do to fuel boiling)

My understanding of "vapor lock" is that the fuel vaporizes in an area that is supposed to have a liqued in it. Such as the fuel pump. when the fuel is in the vapor form it cannot be presurized by the fuel pump and you end up with poor fuel delivery. I am still not 100% sure that vapor lock is the problem but it looks like a prime suspect as it only happens on hot days. Also the heat in the engine compartment will increase during a break due to the lack of air flow.

The fuel could also be vaporizing in the fuel rail, if the back pressure on the system bleeds off the fuel will not be held in liquid form but allowed to vaporize, that is why you hear the fuel pump running when you first turn on the system if the engine compartment is open and the tunes off. I do like your idea of cleaning off the electrical connections and will be picking up some contact cleaner saturday morning before heading to the lake to see if it will happen again.

Thanks for the help, and is contact cleaner avaliable at Wal-Mart? or will I need to go the the auto parts store?

REW