496, Switched to Thru Prop Exhaust, Hard Starting

[stinger222]

Have grown tired of the noise so I switched back to thru prop exhaust. Boats starts right up cold at the ramp, but after running around, stop for awhile in a cove, then try to restart, hard to restart, Finally get it to start, drive around some more, stop. This time I trim the drive all the way up, it starts pretty quick. Drive around again, stop. Restart with drive up, fires right up. Maybe some back pressure from the exhaust bellows??

 

[Watermann]

Seems sort of anecdotal that the motor was tough to start up once. I would test it out a bit more and be careful about starting with the drive up.

 

[NHGuy]

If it was a hot day and you sat for half an hour or an hour the fuel could have vaporized out of the intake tract and possibly also out of the carb bowl. Not fuel injection, right?
You might be dealing with carburetor normal issues that us older folks grew up with and know about intuitively.
Experiment a little.
Give it a little gas while cranking, just a bit. If it's a long crank you could do 1 or 2 pumps to 1/3 throttle while cranking. But watch out, cause if that doesn't start it I might have got you to semi flood the engine. In which case you hold the throttle wide open and the moment it fires pull back so it does not over rev.

Before you shut down keep an eye on your temp gauge. Does the temp get above 180 at idle? If so you could fast idle it a bit to cool things, then pull down the throttle to idle before shutoff.
Also, check to see how it starts immediately after shutdown. I'd bet you can just restart it then without giving it gas.

 

[Bondo]

Ayuh,..... Startin' it with the drive all the way up, it super Tough on the u-joints,.....

Fix yer tune up problem, before ya get yerself a drive problem to go with the motor problem,....

 

[Fun Times]

Have grown tired of the noise so I switched back to thru prop exhaust. Boats starts right up cold at the ramp, but after running around, stop for awhile in a cove, then try to restart, hard to restart, Finally get it to start, drive around some more, stop. This time I trim the drive all the way up, it starts pretty quick. Drive around again, stop. Restart with drive up, fires right up. Maybe some back pressure from the exhaust bellows??

496 normally = MPI if stock from merc.

Do you know if you have a exhaust bellows or exhaust tube ? You should have a tube installed now with this engine package. http://www.bing.com/images/search?q=...ws&FORM=HDRSC2

Did you use the complete conversion kit? http://greatlakesskipper.com/mercury...at-exhaust-kit

 

[stinger222]

the cubic in is 496, but its a carbed modified engine. I have the bellows, I will go with the tube and see if it helps alleviate the situation

 

[stinger222]

installed an exhaust tube, no restart issues the whole weekend!!

 

[smokeonthewater]

Check your timing.... If it accidentally got bumped up a couple degrees that will cause hard starting hot.

 

[alldodge]

installed an exhaust tube, no restart issues the whole weekend!!

While the tube will reduce the back pressure, I skeptical to see this as the issue with restarting. Your probably dealing with a timing issue, taking an MPI motor and putting a carb on it. If your running that lean you could see some more problems later. As NHGuy mentioned, using the throttle only function should have eased the issue