4.3 - Restart Issues

[Boomoo]

How’s the 4.3 1988 Mark twain 23 footer the boat starts right up runs great after about an hour ,then you go to give it throttle and you got nothing it’s bogs down and it will not idle you wait about 10 minutes it’ll start right up and runs perfect again ,,I have change to The wires and plugs, fuel filters for some reason I believe it it sounds like it’s not getting fuel I think it could be the fuel line Or the coil I like to buy a coil I heard I can Buy them from Napa, it still has the points in it I’m just getting tired every time I take it out to the lake it dies on me and I will not idle and this is probably my fifth boat I’ve had in 20 years,, but when it runs it really runs good and I did rebuild the carburetor myself . I bought this boat middle of August this year guy claims that have 15 hours on a crate motor not sure though , Like I said I have a feeling that it’s either the coil or the rubber gas line because when it won’t idle it seems like it’s starving for gas but when you hit the throttle you go look in the carburetor and it does shoot gas down pretty good

 

[Boomoo]

Well I got to figure out how to edit this

 

[Chris1956]

You should post this in the appropriate I/O section. Those guys are experts. Is it an OMC or MerCruiser sterndrive?

 

[alldodge]

Yes, what you working on?

It's almost never the coil.
If carb is not getting enough fuel then you start with the fuel pump, then filter, lines and antisiphion valve

 

[Scott Danforth]

agreed, almost never the coil. most likely its crud in the carb plugging the accelerator circuit.

 

[Boomoo]

Thanks I had a real good friend that had a Marine shop in town here but he got hurt and had to close up so I’m just trying to figure it out myself which is probably a mistake and I’m just learning about this site and it seems to be a really good site and apparently I could buy supplies on it to

 

[Boomoo]

After a hour the boat Idol

I just bought this boat the boat runs and idols great I made it runs real good for about the first 45 minutes to an hour then after that it won’t idle and at times do you get full throttle down and get nothing and let it sit for about a half far that it runs great again the carburetors been taken apart and cleaned and rebuild the best I can use to do that years ago I did put new spark plugs in new On new feel filter‘s new water separator what I bought the boat people say it’s probably not a coil But I had never thought about the vent line coming out of the tank soon as I get my boat back home that’ll be the first thing I check if anybody else has any idea I appreciate it and I’m thinking about putting the electronica condition of it during the winter but right now the book fires right up with just a touch of the key the guy bought it from said it’s a crate motor I find a Weather and saw th but I never thought about the vent line coming out of the tank soon as I get my boat back home that’ll be the first thing I check if anybody else has any idea I appreciate it and I’m thinking about putting the electronica condition it during the winter but right now the book fires right up with just a touch of the key the guy bought it from said it’s a crate motor I find No evidence of that . Oh yes I plan to when arise this myself I used to do my other boats they were all Chevy V8 . I do have one more question it’s a 4.3 I have a 15 x 17 prop runs out at 4500 rpm’s I installed a brand new speedometer everything brand new from the back of the boat to the dash including a gauge I know the boats going faster than 25 but that’s all it reads could I have a bad gauge

 

[alldodge]

Pour the contents of the fuel filter into a clear container to see if there is anything but clean gas.
Next check fuel pressure at the carb by using a inline Tee fitting. The pressure should be between 3 to 7 psi

 

[alldodge]

Looks like your starting another thread for the same subject but the speed-o question

You didn't say if the speedometer you installed was one which uses pressure or water wheel.
The boat speedo gauges work off pressure. The water pushes into the tube as the boat moves, so it depends on how well the opening is facing forward

 

[Boomoo]

I was told I should start one at OMC experts sorry about it I’m very new at this this barometer is done by water pressure

 

[jimmbo]

Your post would be a lot easier to read and understand, if it weren't one long run on sentence.

Crate motor? I certainly hope it is not an automotive crate motor.

Some symptoms point to vapour lock/percolation.

What temp is the engine running at? What temp is the thermostat?

You say it idles for about 45 minutes to an hour, then dies when you give it full throttle? Have you tried advancing the throttle slowly?

 

[alldodge]

I was told I should start one at OMC experts sorry about it I’m very new at this this barometer is done by water pressure

Agree, but the best way is have a Mod move the current thread to this area. I'll see if GA_Boater can merge your to threads to this one so its all together
https://forums.iboats.com/forum/gen...-not-engine-topics/10665361-4-3-won’t-i-don’t

 

[Boomoo]

OK I brought the boat home today from the lake I put air into the gas tank and it came right back out , so the vent tube is completely clogged nothing came out of it I guess that could be my major problem the question I have is how do I remove it it’s a chrome and it’s got two holes at the bottom with the screen and it

 

[Boomoo]

Boat runs right at 160 to 165° and then when I’m just running at a slow speed auto drop back down about 125

 

[alldodge]

If you can put air in the gas tank and it comes out the vent then its not clogged.

 

[Boomoo]

I did put a new fuel filter and water filter separator on and yes the fluid was clean I poured it into a single clear glass there was no water whatsoever thank you

 

[GA_Boater]

Threads have been combined into the original. Can't move it to a motor section cuz Boomoo still hasn't told us what he's working on. And the thread is so scattered with speedo questions, tank venting, carb stuff and idle issues or warm restart issues - I'm too confused to decide.

 

[Boomoo]

I’m working on a 1988 mark twain 23 foot with a 4.3 OMC motor two barrel carb I’m trying to figure how to do things right on this site

 

[Boomoo]

Sorry I upset things the speedo question could have waited not that important like I said I’m just trying to figure things out and If people could help me with it I would really appreciate it , n yes I have been writing to much

 

[GA_Boater]

Moved into the OMC section.

To recap;

She runs about 45 minutes OK, then begins to bog. Is this without shutting off or after restarting?

She has a new water separator/filter.

When the motor starts to bog the next time, open the fuel filler cap. If it runs better, then the tank vent may be plugged, but 45 minutes is a long time to run with a bad/blocked tank vent.