Mercruiser Stalling

[texasvet54]

I didn't see any activity under "stalling" in the Mercruiser Forum, so I hope it's ok to post a question here.

I have a 5.0L Mercruiser I/0 on my Three Buoys houseboat that I purchased back in September. After taking it out a few times before the weather turned cold here in Texas, it started stalling when I dropped the RPM's down to idle to shift into gear. I had a local marine shop look at it and they determined that I needed a new carb.

I took the boat out a few weeks ago and the new carb worked fine. I took it out today and it was stalling out again when I put it in gear while in idle. It didn't stall everytime I put it in gear, but enough to be a problem. I'm going to talk to the shop that put it in this week.

If the carb is good, what else can the problem be? The carb is a two barrel and I assume that the acceleration pump in the new carb is good. Also, I haven't checked the fuel filter yet, but the original owner said that the engine was tuned in the spring of 2010.

I can change the fuel filter, the distributor and the plug wires, but I'd rather know if these Mercruisers are prone to stalling and what fixes it before I start pouring money and time into the engine.

Also, it was around 55 degrees today and the water temp was around 53.

Any ideas?

Thanks,
John

 

[ziggy]

Re: Mercruiser Stalling

but I'd rather know if these Mercruisers are prone to stalling and what fixes it before I start pouring money and time into the engine.

me not being a marine tech. my first assumption would be a bum shift cable. specially if it's an older mercruiser... for sure if it stalls when going from n to f or r. maybe so if it stalls going f to n or r to n..

check out number 4 from this thread.. http://forums.iboats.com/showthread.php?t=288430

 

[cr2k]

Re: Mercruiser Stalling

If the shop did the carb swap for you they are very remiss by not installing a new fuel filter.

if they didn't do the work you should have checked the fuel filter at the very first sign of anything. Just because the PO had it tuned doesn't mean someone changed the filter. And if the filter was changed I would be looking at draining, removing and cleaning your fuel tank.

It is recommended to go with the 1 micron filters used for fuel injection engines as it will pass less of the dissolved solids from the ethanol in fuel these days.

 

[texasvet54]

Re: Mercruiser Stalling

Thanks for the replies.

Before I go and mention the shift cable possibility to the guys who replaced the carb, how would a shift cable cause the engine to stall out? Does the shift cable interact with the carb?

Thanks,
John

 

[texasvet54]

Re: Mercruiser Stalling

Ziggy, I asked my question about the shift cable before I read the link that you posted about how the shift cable kills the engine when shifting out of gear.

The link is for an Alpha Drive. Mine is a Bravo-2. I'm not sure if that matters, but the link did give me enough information to at least sound semi-intelligent when I talk to the shop.

Thanks,
Kevin

 

[Bondo]

Re: Mercruiser Stalling

The link is for an Alpha Drive. Mine is a Bravo-2. I'm not sure if that matters, but the link did give me enough information to at least sound semi-intelligent when I talk to the shop.

Ayuh,... Then ask them to finish tuning the Carb....

Bravos don't have the same cable issues as the Alpha series...

 

[Don S]

Re: Mercruiser Stalling

When exactly does it stall? With only a slightly warmed up engine, it may stall due to carb ice. Once warmed up the problem will go away.
You can check when it stalls by looking down the carb and seeing if the throttle plates are all frosted up.
Upper 40's with a high humidity is a perfect combination for carb ice.

If it's happening when warmed up, then it won't be ice.

Also make sure the choke is opening when the engine is warmed up. I have seen a few carbs that have a single wire choke setup where the rebuilder put a gasket under the choke coil which removed the ground and the choke wouldn't open.

 

[texasvet54]

Re: Mercruiser Stalling

Don,

Thanks for the reply. I warmed the engine up for about 20 minutes before leaving my slip. It stalled when I put it in reverse to manuver in the marina a few minutes later. I then took a short 20 minute trip at around 2K RPM before taking it back to the slip. It stalled on me when I put it in reverse to get a better angle at my narrow slip ( I only have two feet on each side and that's not much with a 52 foot boat.)

As far as carb ice goes, is it possible for it to form when the water temp and the air temp are both in the low 50's?

Also, with water temp in the low 50's, at what temp should the engine be running?

Thanks,
Kevin

 

[HPTGreyGhost]

Re: Mercruiser Stalling

You could try bumping the idle up a little. I know my engine is under more load in reverse than forward and that could be your problem. Adjust the engine idle up 100 RPMs, see what happens. If it doesn't work, you can always turn it back down.

An engine can idle perfectly find when testing on land, but moving under load can be a different story all together.

 

[GWintz]

Re: Mercruiser Stalling

Background...I have a 1996 Mercruiser 454 7.4l Bravo with 258 hours in a Caravelle Interceptor. In 2005 I took the engine out for some fiberglass repair and it sat in my buddy's (He is a boat mechanic) shop for 6 years before he installed it in October of 2011. All that was changed were plugs, wires, distributor, coil, etc...starter, alternator, carb rebuilt, fuel filter, oil/filter,power steering pump, drained old gas (did not clean tank...had gas in there for 6 years). It ran fine when I picked it up in 10-11. I changed the fuel pump last week when I attempted to start it up from the winter and was not getting any gas to carb.
I took it out today and this is what happened:
After I launched the throttle cables gave me a problem but fixed themselves once I got them moving a few times (did not have this problem in the driveway with muffs on).
I ran gently (half throttle) for about 10 minutes until I reached the wake zone...whereas I smelt burning oil...opened up and saw smoke. Burnoff from spilled oil...
I noticed the circulating pump pulley was wobbling, so I turned around and drove it to my buddy's shop where he seemed to think my pulley was warped. We pulled it off but it didn't seem warped to me put it back on and he told me to bring it by another day and we would get it changed.
In attempts to work all of the bugs out from it's 6 year break, he said the wobble would be fine to run until we could get it changed. So I ran down the river for another 30 minutes and noticed a slight sputter when running at half throttle.
So I turned around and started back towards the landing because it seemed to me that my prop hub was slipping. After I turned around the sputtering got worse and forced me to idle all the way back to the landing. It did kill on me one time on the way back as I was idling. I'm no mechanic and have read all of the stalling threads but wanted to ask advice on my specific situation on what to do about the sputtering. Gas is good but it seems to be a fuel issue...with regards to the wobbling pulley, I'm pretty sure my circulating pump is bad...Can these two be related? What advice for troubleshooting the sputtering?

 

[Don S]

Re: Mercruiser Stalling

Welcome to iboats GWintz, you need to start a new thread of your own with all that information, not hijack someone elses thread.

 

[GWintz]

Re: Mercruiser Stalling

Don, I've tried and cant find how to start a new thread

 

[Don S]

Re: Mercruiser Stalling