Mercury I/O Problems

[ducksdemise]

I have a Merc cruise 5.0 v8 engine
I am having difficulty starting the engine( I have to crank the starter for about 30 seconds with the shifter wide open before it starts) once it starts I cannot idle the engine or shift into forward or reverse without it stalling. Once I can get it into gear I have to run it at a high idle for it to keep running.
I have had both shift cables replaced recently. Once I get it into gear the engine runs strong. The engine is on a 1992 Thompson 24' Fishermen

Thanks,
Jim

 

[Don S]

Re: Mercury I/O Problems

When was the last time it had a full tuneup? Compression check, is the choke working properly? How about the accelereator pump in the carb?

 

[ducksdemise]

Re: Mercury I/O Problems

Don,
Just did a compression check
#1 135 #2 135 #3 135 #4 135 #5 145 #6 140 #7 135 #8 130
Leak down test
#1 20% #2 18% #3 14% #4 18% #5 12% #6 18% #7 14% #8 16%

Just did a tuneup in late June.
Plugs wires etc.
Thanks,
Jim

 

[littlebookworm]

Re: Mercury I/O Problems

You didn't say if you had checked the automatic choke or the accelerator pump on the carb. It sounds like one, or both, is the possible culpit. Hy

 

[ducksdemise]

Re: Mercury I/O Problems

As far as I know the carb has not been touched.
An another note
how do the numbers look on the the tests.
Thanks,
Jim

 

[erie_guy]

Re: Mercury I/O Problems

It would be interesting to see if your fuel is good - and free of any water. Some water content can make an engine cantankarous. It took a tank removal and draining to fix our engine a few years ago. We were getting spray into the tank from a vent that was to close to the bow wave.

erie_guy
Port clinton, OH

 

[jtybt]

Re: Mercury I/O Problems

If your choke is working...

The process of full throttle is the usual way to start a flooded engine.

Float set wrong or stuck float valve or leaking well tubes.

 

[MDJ1016]

Re: Mercury I/O Problems

I had a similar problem on my Four Winns Liberator, when going into reverse the boat stalled. Long story short I had the bellows and other seals replaced on the boat and opted to replace the shift cable(s) at the same time. Once this was done the problem went away. My suggestion is if a dealer replaced the cable, ask them about an adjustment. I believe there is also a sensor (trim sensor?) that has something to do with the shifting. I will be into the boat dealer (well at least the one I enjoy chatting with) this weekend and ask him. Any issues if I print your posting off and take it with me to him?

 

[freeone]

Re: Mercury I/O Problems

Don,
Just did a compression check
#1 135 #2 135 #3 135 #4 135 #5 145 #6 140 #7 135 #8 130
Leak down test
#1 20% #2 18% #3 14% #4 18% #5 12% #6 18% #7 14% #8 16%

Just did a tuneup in late June.
Plugs wires etc.
Thanks,
Jim

comp check looks good, leak down borderline up to 15% is acceptable

 

[freeone]

Re: Mercury I/O Problems

did you have this problem b4 the cables were changed out? does this happen engine cold/hot or at all times? sounds more like a fuel issue. mixture/idle adjustment throttle cable adjustment.

 

[180shabah]

Re: Mercury I/O Problems

Start with, is there fuel in the carb at startup - could take thirty seconds jsut to fill the fuel bowl if it is empty.