Resolved - Engine Stall under load

R

Rick D

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Went out today into the sound. Boat started and idled fine and ran for 30 minutes at no wake speed just fine. However, when I went to bring it up on plane, my port engine would stall at around 2500 rpms... but only under load. I neutral, I can rev the engine for sustained periods without problem and it will return to idle. But in gear... between 2000 and 2500 I see the RPM's start to fluctuate and then it just cuts out.

Carb related? I read elsewhere it could be coil related or even shift related.

If it's carb, is there a more reliable carb than the 2 barrel mercarb? Engine is a 1997 merc 5.7L with the factory 2 barrel mercarb which I cleaned and rebuilt prior to the season.

Thanks,

--Rick
 
Can you "push through it". Meaning if you play with the throttle while it's trying to die can you get past the "dead zone" of 2500 and keep going up to 3300?

If not I would agree it's a clogged fuel filter like the others said and does your have the gold mesh one right where the fuel line screws into the carb along with the inline filter?

And....... Check the vent opening on the side of the boat for the gas tank. Them mud bees love that area to play, so don't the spiders,

Also you can try to open your gas fill cover and see if that helps for a minute. If it does that's another clue to your clogged vent line.

And if your sucking air into a loose fitting or cracked hose that will do it.

Hope it's one of those as they are all pretty easy fixes.
 
rb2@gr5tgetakey - fuel filters have less than 10 hours on them... but will try changing anyway.
rb2@gr5tsprtplt - don't think there are any vacuum lines on that engine, except one which is intact... could probably do the wd40 trick on the manifold and at the base of the carb to see if it has an effect.
rb2@gr5tboatcrazy - fuel pump.... maybe... easy way to determine is to swap with my starboard engine and find out.
rb2@gr5tJLC - no, it will not push through... it cuts out before it can. Good to hear someone else thinks it might be fuel filter related and my carb does have a small inline filter right at the point of entry into the carb... will check that one as well. Don't think it's the vent as the starboard engine ran fine.

--Rick
 
when you remove the filter dump the contents into a clear container and see what's up.
 
hmm... but if it's a fuel filter issue, why would it only happen in gear and not at a sustained rpm out of gear?
 
When you're running in gear, there is a greater strain on the engine than when you rev the engine in neutral. You pull more fuel then at greater pressure. I would check the filter and the flex hose section of the fuel line. They have been known to collapse internally when the pressure increases. Blame the e10 fuel for that. If you find the hose is collapsing inside, I suggest you replace that hose on both engines as the other one is sure to start to give you problems soon, as well. Hy
 
Because fuel used is related to power produced not RPM
 
I don't know why the carb has been disounted. This is a primary indication that the float level is too low or the float is hung up.

The fuel pump is working or you wouldn't be running at idle.

JMO
 
anything is possible but floats dont normally get set low on their own. If they get heavy they will flood, not starve.
Limited Fuel pump capacity is also possible as are air leaks in the fuel lines plugged tanl pick up splugged vents etc.
IMO carbs are second only to coils in being replaced unnecessarily.
 
quote:
Originally posted by absolute

How old is your fuel?

Click to expand...


Fuel is a couple of weeks old.

I was told by the owner of the boat yard I had my boat at over the winter that he suspects the carb as well. I can always switch carbs between engines to isolate whether it's a carb issue or not.

--Rick
 
Rick I had the same issue last week.
got it restarted and got back in. Pulled the fuel filter to see if water was present. Poured it into a clear container..no water went and replaced secondary filter. I also have a barrel plug that controls many functions. Took apart and cleaned it put some diaelectric(sp) grease on it took it out today ran fine then when I slowed down it stalled. Everything was out that is related to the barrel plug. But after a few minutes everything came back and restarted the engine. So bottom line I think my problem may be that plug and you may have same issue. I have followed your trials and tribulations over the past few months....welcome to boating. You have done a great job resolving the various issues you have had. I am curious how this is resolved.
 
OK, so here is my game plan for solving this issue:

Friday, I will take my boat out into LI Sound and confirm the stall at 2200 RPM's on the port engine.
I will inspect the fuel lines for anything not tight that might be allowing air to get into the system.
If the above doesn't fix it, I will then change the fuel filter and try again.
If the above doesn't fix it, I will then switch my carbs between port engine and starboard
If the problem stays on port, I will swap fuel pumps between the two engines.
If the above doesn't fix it, I have to start considering the problem might be ignition related in some way and will cross that bridge when I get to it.

Anything obvious I am missing?

Thanks,
--Rick
 
Put a new Rochester 2 Barrel on the engine and took it into the sound today. No stalling at 2200 so it appears to have been the carb.

--Rick
 
There is no mechanical problem that enough money can't solve.
 
You say you plan to replace the in-line fuel filter, but what about your water separator cartridge?
 
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