Dies when throttling up from idle after warm up/ 89 merc 3.7 2bbl

[karayj]

So I'm trying to figure out why my boat run so well for the first 45 minutes of operation and then if I turn off the boat to anchor somewhere restarting it is almost impossible unless if I don't let it sit for more than 30 minutes. if I want to start up before that I have to use starter fluid and is extremely difficult And I can only idle the 2nd I try to get any power it just bogs out and dies immediately when I do start it with starter fluid and I get it running putting into gear is a struggle sometimes it stalls three or four times until I can get it to run.

Now many people will say it's a fuel problem and I get that I do plan on rebuilding the carb but I'm wondering could this be a timing problem because again for the first 45 minutes it responds to any throttle it's idle smooth I'm sure I could shut it off and it turned right back on no problem but I haven't tried that yet 'cause I don't want to get stuck. My plan is to get a timing light on it and do 4 degrees advance I think it is on my 89 3.7 merc.

The problem is I really can't test this until I'm on the water so I want to try to nip this in the Bud right away now I know most of you will say well do the timing and rebuild the carburetor but I'd hate to do all that work on the carburetor for nothing if it doesn't need to be done. Also if it was the carburetor wouldn't I have problems with the accelerator pump not functioning properly or the float immediately not necessarily after it warms up?
One last thing I want to bring up to give some clues to everyone is after idling around for at least an hour and 15 minutes the temperature on the boat never gets in the middle of cold and hot it always runs a little bit above cold which is interesting makes me think that the temp switch is broken But I did test it last year with an old meter and it did change with different temperature ranges .

 

[Scott Danforth]

stop using ether.

pull your carb apart and clean it.

have you serviced the points? as points wear, your dwell changes and so does your timing. so file the points, gap them to 0.018", then verify that the dwell is between 28 and 32 degrees, then set timing.

also, your lower shift cable most likely needs adjustment or replacement

 

[guitarsnlikker]

My 2010 3.0L mercruiser used to have hard time starting when hot. I set base timing properly (my engine is 2deg ATDC) and it fixed it.

 

[karayj]

I will do the timing tomorrow.... I am getting a dell meter and timing gun! Back to the days of my 69 Z28. Now building the carb was my plan. I need help finding the correct kit I spent 1 hour looking . The back of my carb has a stamp13899564 3704 below that number . I need help finding a kit number.

 

[Scott Danforth]

My 2010 3.0L mercruiser used to have hard time starting when hot. I set base timing properly (my engine is 2deg ATDC) and it fixed it.

and how does this help the OP? completely different engine, fuel system and ignition. other than both being 4 cylinders and carbureted, that is where the similarities end.

 

[guitarsnlikker]

and how does this help the OP? completely different engine, fuel system and ignition. other than both being 4 cylinders and carbureted, that is where the similarities end.

OK. Thank you. Wont happen again.

 

[karayj]

Ok so the timing after running 10 min was at about 18 degrees btdc I corrected it to 4 btdc hoping that helps Dwell is good point are .22 so now let see what happens on the lake. Next week carb rebuild..........

 

[karayj]

I forgot to mention something about this acceleration issue that I'm having after riding around at idle for an hour the boat never really warms up it always stays a little bit above the cold mark never in the middle and I'm wondering if that could be why when you go to give it gas it It stalls.

I know it's a long shot saying this but I'm just trying to look at every single angle yesterday I put in a new flapper in the exhaust system and it seemed to warm up a little bit quicker now not sure why I'm wondering if that's going to help out.

The concern is when I get to the boat ramp and turn the key she starts right up immediately idles fine if I idle around for about 40 minutes and shut it off and go to turn it back on again it takes forever to start I have to use starter fluid and the second I go to put it into gear once I get it running it stalls again

 

[karayj]

Update>>>> I rebuilt my carb not all parts where done (metering jets) and power valve would not budge.
I noticed the screen in the carb was ONCE again 40% clogged with some muck . After installing the carb I ran the boat and things were fine. The next day on a hunch because about a month ago that fuel filter inside the fuel pump was a complete mess look like it was 15 years old on a hunch I decided to take another look at it one more time because of the muck that I was seeing in the screen in the carb .

Well the filter in the fuel pump was very very clean which tells me there's nothing wrong with the gas tank 'because I was about to empty that out because of the muck that I was seeing in the screen. I am wondering in the muck was form the fuel pump.

When I went to put the fill filter back for some reason the boat would not start after a few tests I removed that same fuel filter in the fuel pump and put an inline fuel filter instead and the boat runs great now also there's no hesitation in power.

My plan to go forward is not to have any type of fuel filter inside that fuel pump if I have an inline 1 there's no real need. My question is when I did take it out on the Lake And I gave it full throttle it acted as if it was just at about 50% power I was really surprised the lack of power any ideas?

 

[nola mike]

1. Exhaust flappers are unrelated
2. Running fine for an hour doesn't point to a carb issue unless your choke is misbehaving or your fuel vent is clogged
3. However, tough to eliminate that when the carb rebuild was half assed. Power valve circuit could definitely cause... Power problems
4. Don't run an inline fuel filter. Dangerous/illegal
5. DO get a proper canister type fuel/water separator filter. Also, pull your fuel line before the carb and run it into a clear container. See what the fuel looks like. Your investigation so far won't show if you have water in the tank.
6. What do your plugs look like after running?
7. What's your starting procedure?
8. Is this a new to you boat?
9. Is the temp the same as it's always been? Check actual temp with an ir gun or a radiator cap with an integrated thermometer. Also unrelated though

I would guess that 75% of my issues over the years with multiple boat/other engines is water in the tank...

 

[karayj]

I will run fuel to a bottle to look for water>>>Update. I removed the filter in the fuel pump because after checking my fuel filter for debris update (it was clean) it would not start. Then I put back the inline and if fired right up . I think I may have put the filter in incorrectly after a previous inspection because of debris found in the carb screen. Well after I removed the fuel pump filter IT RUNS GREAT no more hesitations / starts back up after riding around for 1 hour/ No more debris in the carb screen. Now I have to figure out what is wrong with the way I am installing the filter of do I have the wrong filer in the fuel pump.

 

[karayj]

Turns out this could be a coil issue cause it happen again today . I ready that an over heated coil will cause problems. I am upgrading to a 3 ohms coil from 1.5. You see when you run your boat for 20 min straight then stop the engine compartment gets hot and there is no venting since you are not moving. So after 10 min the engine compartment must get over 200 degrees. So the coil fails after 10 min and wont be ready for 60 min even with venting or the cover removed. So I am getting a 3 ohms coil that can handle heat.

 

[CaptnKingfisher]

1. Exhaust flappers are unrelated
2. Running fine for an hour doesn't point to a carb issue unless your choke is misbehaving or your fuel vent is clogged
3. However, tough to eliminate that when the carb rebuild was half assed. Power valve circuit could definitely cause... Power problems
4. Don't run an inline fuel filter. Dangerous/illegal
5. DO get a proper canister type fuel/water separator filter. Also, pull your fuel line before the carb and run it into a clear container. See what the fuel looks like. Your investigation so far won't show if you have water in the tank.
6. What do your plugs look like after running?
7. What's your starting procedure?
8. Is this a new to you boat?
9. Is the temp the same as it's always been? Check actual temp with an ir gun or a radiator cap with an integrated thermometer. Also unrelated though

I would guess that 75% of my issues over the years with multiple boat/other engines is water in the tank...

Never knew inline filters were dangerous or illegal. What makes em dangerous

 

[karayj]

Never knew inline filters were dangerous or illegal. What makes em dangerous

So the tank was completely emptied and dried before the season this didn’t have a problem until I replaced the points and I adjusted the air mixture to 2 1/2 turns. That’s all after the new points and air fuel mixture change this started to happen. I’ve installed an old carburetor one that had a return spring problem and it’s doing it with that also so it’s not Carburetor related to me. Again I’ll say it the only way to really use this boat is you start it up and you just put it in gear and idle then you kind of slap the throttle very lightly a canna Boggs a little bit but continues to run in after about 20 seconds it catches up to the proper throttle measurement and she starts to pick up speed and then you can go full throttle. Too much gas at once but how could that be on 2 Carburetor’s

 

[CaptnKingfisher]

Bogging and needing starting fluid sounds like you're running rich. I'm not a fan of setting air mix by "x" amount of turns. I use an accurate tachometer (my timing light) and slowly turn idle mix screw clockwise until rpms begin to drop due to lean condition, then turn screw counterclockwise slowly and you'll observe rpms begin to increase. Continue turning until rpms start to drop due to a too rich condition. Then turn clockwise again, making a final adjustment for maximum rpms and engine smoothness. After youre done you'll probably need to use your idle speed screw to lower rpms back to spec.

Also since you changed points, it's worth asking, did you do things in this order.. set point gap, set dwell, set timing? All these things affect each other

 

[karayj]

So the tank was completely emptied and dried before the season this didn’t have a problem until I replaced the points and I adjusted the air mixture to 2 1/2 turns. That’s all after the new points and air fuel mixture change this started to happen. I’ve installed an old carburetor one that had a return spring problem and it’s doing it with that also so it’s not Carburetor related to me. Again I’ll say it the only way to really use this boat is you start it up and you just put it in gear and idle then you kind of slap the throttle very lightly a canna Boggs a little bit but continues to run in after about 20 seconds it catches up to the proper throttle measurement and she starts to pick up speed and then you can go full throttle. Too much gas at once but how could that be on 2 Carburetor’s

 

[karayj]

So on the old Carburetor that was OK just had a return to idle problem I took the boat out I drove it for about I don’t know four minutes I shut it off I decided I wanted to react or somewhere else it won’t start again because it seems flooded it stinks of gas what the heck is that and the old Carburetor did the same thing. I
have a carb kit I’m gonna rebuild the other one the one that has a good return spring back to idle but I’m getting sick and tired of this where I can throttle all the way up and I can never restart the boat after I shut it off unless I sit for 20 minutes and the coil has been changed.

 

[CaptnKingfisher]

Definitely sounds like flooding and i think your idle mix is set too rich. When you're flooded and can't restart the engine, have someone hold the throttle plate open while you crank and you should be able to start it up like that so you don't hafta wait 20 minutes.

 

[karayj]

We did that full throttle scenario it only makes it backfire through the carb.
I change the coil to a 3 ohm now she starts right back up so the problem is fixed.
I still have an issue on another carb, this tells me it is not a carb issue . I don't have a dwell meter. If I sit for a while and then start it I try to give it gas and if I get to aggressive on the throttle it pops though the car and dies. I then I have to find a low idle cruise for a while then i can give it full throttle. If I try to soon it pops and dies.

 

[CaptnKingfisher]

We did that full throttle scenario it only makes it backfire through the carb.
I change the coil to a 3 ohm now she starts right back up so the problem is fixed.
I still have an issue on another carb, this tells me it is not a carb issue . I don't have a dwell meter. If I sit for a while and then start it I try to give it gas and if I get to aggressive on the throttle it pops though the car and dies. I then I have to find a low idle cruise for a while then i can give it full throttle. If I try to soon it pops and dies.

Get a dwell meter. If dwell is off you've got no chance at getting this thing to run right. Verify dwell then check timing