OrangeF150
New Member
:huh:1998 with the 3.0 merc.Going from off idle to full throttle it has a bog.I have to let off for a sec and then get back into it.Any ideas?
Slight bog when stabbing the throttle wide open
- Thread starter OrangeF150
- Start date
JimG
Well-Known Member
- Nov 4, 2008
- 6,085
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- 2007 310 DA
Kohler 5ECD
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- Twin 350 Mags
Raw Water Cooled
V-Drives
So if you leave the throttle down it won't recover? Maybe a spun hub on the prop?
tdappleman
Active Member
- Dec 17, 2007
- 1,608
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- 1996 270 Sundancer
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- New twin 4.3's - 235hp each with Alpha 1 Gen 2 Drives
Have you made any changes lately? You could try adjusting the accelerator pump if yours has one.
- Feb 14, 2009
- 1,361
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- '07 42SS Carver, full electronics array
'03 380DA, RL80C+, ST7001, Kohl 7.3,4kw o/array sold
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- 8.1S Crusader express drives
The first question is "carb or EFI"? Bogs can be a lot of things, or a couple of little things not being perfect. The problem could be very obscure, but it probably isn't.
Assuming carb...start with the basics. Check fuel filters (water gets in them and stuff clogs them...there may be a couple, they are cheap, replace them), clean spark plugs (look at the tips, they'll give you a clue about combustion...anything but light brown wear and its probably not a bad idea to compression check), check the spark plug wires back to the distributor cap, pull the distributor cap and check for corrosion and gunk on the connections and clear flame arrestor (your basic fuel, fire and air). In all likelihood, these steps will identify the culprit.
With the basics solid, understand the systems you are working with...to accelerate, an engine needs to enrich the air fuel mixture and increase the timing advance. The enrichment is accomplished in a carb usually through a power valve or accelerator pump. If you take the flame arrestor off and look down in the carb, and pump the accelerator, you may be able to see a little squirt of fuel coming out (if not, repairs of this nature are probably beyond the scope of entry level DIY). Also, even on a carb system, in 1998 I'm thinking you had some sort of electronic spark advance...also beyond the scope of entry DIY, but if you get froggy, hook a timing light up to the engine and you can watch the advance).
Assuming carb...start with the basics. Check fuel filters (water gets in them and stuff clogs them...there may be a couple, they are cheap, replace them), clean spark plugs (look at the tips, they'll give you a clue about combustion...anything but light brown wear and its probably not a bad idea to compression check), check the spark plug wires back to the distributor cap, pull the distributor cap and check for corrosion and gunk on the connections and clear flame arrestor (your basic fuel, fire and air). In all likelihood, these steps will identify the culprit.
With the basics solid, understand the systems you are working with...to accelerate, an engine needs to enrich the air fuel mixture and increase the timing advance. The enrichment is accomplished in a carb usually through a power valve or accelerator pump. If you take the flame arrestor off and look down in the carb, and pump the accelerator, you may be able to see a little squirt of fuel coming out (if not, repairs of this nature are probably beyond the scope of entry level DIY). Also, even on a carb system, in 1998 I'm thinking you had some sort of electronic spark advance...also beyond the scope of entry DIY, but if you get froggy, hook a timing light up to the engine and you can watch the advance).
Last edited:
OrangeF150
New Member
When it does it I have to back off for a split second ,then slowly get back into it.My hub was looking in bad shape.Looking for another prop as well, my current prop is a 17 pitch.
OrangeF150
New Member
I dont think mine has a fuel filter, or at least I dont see one.I am going to replace the plugs this year anyways when I get her out.
- Feb 14, 2009
- 1,361
- Boat Info
- '07 42SS Carver, full electronics array
'03 380DA, RL80C+, ST7001, Kohl 7.3,4kw o/array sold
- Engines
- 8.1S Crusader express drives
A fuel filter is in there somewhere...either in line, or mounted on a bulkhead, or a little one in the front of the carb. Go to your carbureator, find the fuel inlet, and work your way back to the tank...you'll find it. If you didn't know it was there, it probably needs replaced. The reason its important is that fuel pressure from the fuel pump keeps fuel pressure in the carbureator jets and bowls. If the fuel pressure is low due to restrictions, then the bowls and channels can't refill as fast as may be demanded by the needs of the engiine.
aqua*holic
New Member
My older boat had this same problem. The accelerator pump has a diaphragm that pumps extra gas from the float bowl to the venturi. There is a little ball that acts as a check valve that was stuck in mid travel. You could see gas squirting into the venturi, but it was only a partial squirt, as some of the gas was going back into the bowl. I ended up rebuilding the carb, but I suspect that if I had just popped that little ball loose all would have been fixed.
McNally260DA
New Member
Not really sure what your problem may be. But be aware of the ethanol in most fuels now. I use stabil in every motor now except my truck. Its a real problem.
- Oct 3, 2006
- 2,019
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- 04 SeaRay 185Sport, Smart Tabs, Mageln Meridian Gold GPS, Hbird Matrix 87 dept/ff/gps/cp, Uniden vhf
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- 4.3L 190HP, Alpha 1 1.81 ratio, 14 1/4X21 Turning Point Prop
A spun hub would make the engine rev up when you get on the throttle hard, you would have to let off and ease back in to get going, also if you happen to be trimmed up a little you could have blow out which also would be a high revving engine.
If the engine is bogging/dieing out on heavy acceleration then the above advice is dead on.
If the engine is bogging/dieing out on heavy acceleration then the above advice is dead on.
JimG
Well-Known Member
- Nov 4, 2008
- 6,085
- Boat Info
- 2007 310 DA
Kohler 5ECD
- Engines
- Twin 350 Mags
Raw Water Cooled
V-Drives
- Oct 3, 2006
- 2,019
- Boat Info
- 04 SeaRay 185Sport, Smart Tabs, Mageln Meridian Gold GPS, Hbird Matrix 87 dept/ff/gps/cp, Uniden vhf
- Engines
- 4.3L 190HP, Alpha 1 1.81 ratio, 14 1/4X21 Turning Point Prop
Was not aimed at you JimG, :grin: was just trying to get the OP to verify what was really happening. The more the op tells us the better we can help.
- Oct 4, 2006
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Sounds carb related to me too; had a similiar issue in my 3.0 when I got it. Purchased a rebuild kit and fixed the problem. Always a good thing to do on an older engine that you don't know the history about. And it is a very DIY project, with a minimal amount of tools necessary to do the project. Sometimes they even come with instructions, but the very least an exploded view diagram.
Your fuel filter is probably just a screen inside the fitting for the inlet to the carb. If you unscrew the fuel line from the carb, you'll see it there.
Tom
