Engine stalls

[bigtoe]

Hi just had an engine re built.
Everything runs lovely on the muffs, took it out the first time and after an hour and some slow driving engine starts to run a little rough, going onto the plane it stalled. Re started but would not go into gear without engine dying. Left it a while then managed to get home. I thought maybe bad old fuel so emptied it all out and changed the water sep filter.

To night we took the boat out again, this time after 20 mins of pooling around we went to go on the plane and again engine stalled. Not so easy to start it and would not go into gear with out it stalling. Eventually I got it into gear and went home . Engine on the muffs now runs lumpy.

When at the dock I took all the plugs out one by one and checked for water coming out whilst turning over but none was seen. Changed both manifold and riser pipe 6 years ago. 2nd plug from the rear whilst removing it I heard a pressure release.

Running a 3 l GS on a 99year fourwinns horizon

Thanks for any input, very frustrating

 

[Fun Times]

Re: Engine stalls

Hi there! I'd recommend performing a engine cylinder compression test while the engine is warm as you may have a head or head gasket problem. Hope I'm wrong, good luck.

 

[bigtoe]

Re: Engine stalls



Hi fun times many thanks for your help. I just did a test all seems ok 3 at 175 and one at 160. The 160 is at the front of the boat. Do i need to do a raw water pressure test or does that prove the water system as well ?

I took a pic of the plugs as well.


Thanks

 

[bigtoe]

Re: Engine stalls

A further update. Once I did the comp test , I went to restart the boat. I wouldn't start and kind of back fired. I guess thi must be because of excess fuel in the system after turning it over to do the compression test. I took of the flame arrest or and saw the butterfly on the choke jammed closed. I pushed it free and left the excess fuel itme to evaporate. Then she starred ok . I left it to run for 15 mins or so and checked the plugs . They are now looking much cleaner and dry on the threads not black and oily.
Could my problem be a sticking choke ?
Also there was no pressure build up this time when I removed the plugs.

Thanks in advance

 

[insttech1]

Re: Engine stalls

For a freshly rebuilt engine (or at the beginning of each season, for that matter), I'd put in new plugs.
They're cheap. And those look like they've been thrashed w/ fogging oil, or gunk from before the rebuild.

And yes, a choke clamped close would cause some of your problems.

Start it up from cold w/ the arrestor off, and watch the choke as it warms up. See if everything works as it should.

 

[bigtoe]

Re: Engine stalls

Hi Innstech1
I am sure the plugs are new but will change them any how. They cleaned up after I freed the choke. But I am not sure if the back fire ( or explosion in the exhaust) could of jammed the choke valve. As I had seen the choke work ok before my latest trip. Here is a pic of what the plug looked like after freeing the choke
I am hoping to get her in the water again tomorrow.
Apart from looking at the choke to make sure it's operating any thing else I should look at whilst I am on the water , if it starts going wrong again?
One other thing I remember seeing was a drop in oil pressure but I am told this would happen if it all is running badly ?

Thanks

 

[bigtoe]

Re: Engine stalls

Hi well after 3 or 4 hrs on the water watching the carb and choke closely .
The choke worked perfectly today , but when going onto the plane slowly a dead spot that has always been there is now a lot more noticeable especially when gradually exelerating. We also noticed a smell of fuel at that point so maybe the carb is over fueling ?
She cut out three times on the plane today . Twice when going onto the plane and once whilst being there for ten to fifteen mins.
I also noticed a fluctuation again in oil presure,
Each time the engine stalled I checked the plugs. I would say they looked perfect not oiled up or wet.
A couple of times I took the plugs out though to check them I did get a pressure rush out . Similar to doing the compression test. I have never had this before, is it normal ?
Many thanks

 

[insttech1]

Re: Engine stalls

Plugs look way better now that they're cleaned.
I had major problems w/ hesitation during throttle-up.
Mine turned out to be a combo of a bunch of things:
mis-tuned throttle cable (it was set to "push" the throttle closed and about 3/8" from where it should have been)
carb base plates "sticking" while throttle going thru its travel (very hard to describe)
someone had tweaked the lever arm to the diaphram pump (THAT was hard to find until ordering a new one and comparing!!)
needed new rotor and cap (those two helped a lot!)
semi-loose plug wire
and all of this was AFTER a full carb rebuild and tuning.....pain in the butt!!

But in your case two things pop up:
Your engine drops RPM while on smooth plane. That makes me think something in the fuel line/filter is messing w/ the carb.

And worst of all, I have no idea about the "pressurized" cylinder/s when pulling plugs.
How many do it? Is it always the same one/s?

As stated above, that would mean, at least to me, that both the intake/exhaust valves are closed. That's not good.
Maybe time to pull the valve cover real quick and see if something looks amiss??

But, who did the rebuild?? Is it under warranty? Have you contacted them?

 

[bigtoe]

Re: Engine stalls

Thanks. This time it was the rear cylinder that I had pressure from whilst removing the plug. ( it did it twice) the time before it was either the one next to it or the 2nd from front. The last time I took the plug out though no pressure.
It was a engineering shop local to me who rebuilt it. To be fair they have not billed me as yet so I guess the warranty is there on that bases. It was all done very chilled.
Just so I am not panicking to much ( as I don't understand it) if the intake and exhaust valves are closed what are the implications and would that actually stall the boat as well?
I will pop in and see him early week and ask him about it. I need to find out how much I owe him as well!
I must say I ran it at idle for at least two hours with out it missing a beat.
It does sound fuel related to me now. The boat was not used last year at all so I was thinking carb strip down and clean. But first I will get a new cap and rotar arm, just in case..
The only other thing I can think of fuel wise. Would the float level have any thing to do with it? I had a problem with the carb just before I had the engine rebuilt, the fuel kept flowing into the carb ( pouring in) I removed the float chamber and found the float was not shuting the fuel of , so I bent the float arm up a bit higher so it shut down.

Many thanks

 

[bigtoe]

Re: Engine stalls

Bump