120 Mercruiser 2.5L - No spark

[Mercruiser 120]

How come when I put stuff

 

[Mercruiser 120]

How come when I put stuff

In the mercury/mariner outboard forum nobody answers, but over here I have one problem and you guys help right out. I don’t get it

 

[alldodge]

THere is more of us on this side, I saw your post on the other

 

[Mercruiser 120]

Post about my Mercruiser now. Carb floods so I checked the needle and seat, re-cleaned everything. Boat works ok. Shut key off and gas drips from venturi’s a bit.
Thought it was the mechanical fuel pump, so I put my other one on. Pressure test at 4.5lbs. To start the boat I have to give lots of throttle. Runs ok, as soon as I come back the other way to rev down, there is nothing there and just dies.
Do you know what would be doing that. But I can sit at the dock and it will rev from half, I can push it full, sounds good, like it is getting all the gas it needs.

 

[alldodge]

Having to give it lots of throttle to start and the drip when shut off would be a bad seat or incorrect float setting. I'm thinking the float is set to high. Your flooding and it dies

 

[Mercruiser 120]

Having to give it lots of throttle to start and the drip when shut off would be a bad seat or incorrect float setting. I'm thinking the float is set to high. Your flooding and it dies

I opened her up last night. I have it like the schematic you sent me. When it’s up it is 3/8 of inch from gasket to toe.
When it drops(on dry land - air horn off in my hand) it is less then 1 3/4 inches hanging down if I measure to the exact same spot.

 

[Mercruiser 120]

 

[Mercruiser 120]

Everything is brand new. I had it all rebuilt. Now that I have pulled it all apart, I could have done it myself with a kit.

 

[Mercruiser 120]

The seat is totally clean, has a brand new gasket(nice, red fibre washer) on it. The needle is new, tip looks perfect

 

[Mercruiser 120]

So if I set the float to shut the needle a bit sooner will stop the flooding/the drip.

 

[alldodge]

Measurements are correct, needle and seat are clean and pressure is 4.5 psi but it still leaks. Doesn't make sense unless the float is to heavy

Yes, you could set the float to shut off sooner.

 

[Mercruiser 120]

With the 4.5 psi pump on now it wont run below 2200-2400 rpm. If I bring the throttle below half throttle at the dock, it just dies out. To start I put neutral 3/4 just to get it going again

 

[Mercruiser 120]

So I thought my pump was causing the flooding problem. It measured 6-7.5 lbs output, so I put the fuel pump I’ve always run. Now it won’t get anywhere near idle. When I undo the fuel line at the carb, it pulls off and squirts as if it was under pressure, like couldn’t get in the carb

 

[alldodge]

It was able to start back up and now it doesn't. Something is getting worst. The points might be closing up if the screw wasn't tight enough

Did you ever run a compression test?

 

[Mercruiser 120]

It was able to start back up and now it doesn't. Something is getting worst. The points might be closing up if the screw wasn't tight enough

Did you ever run a compression test?

Yep. For an old girl it was 135-140psi.
So check under the distributor to make sure everything is set perfect.
The carb specialist(I would just take it to him to fix but it is 1.5 hrs away) always texts me back tries to help. He told me to vent the gas tank, to see if the rpm lower will stay running.

here is a re-cap. Last weekend, boat ran decent, 3/4 throttle, wide open…amazing. If I cut it back to slow down off plane it will cough out, just die. Half the throttle in neutral, will start right back up. Put the throttle down, will jump right out of the water. If I come to close to the dock on the way in and pull the throttle back quick, it will die.
So I cleaned needle and seat, measured float drop and closed, seemed in spec.
Didn’t have time to try it.
Yesterday, put it in the water. Pump the throttle leave 1/3 of way down in neutral starts up, runs fine. Go out drive on plane, even doesn’t cut out when I slow down. No gas out the vent on the air horn like last time. Little bit of dripping when I shut key off, but not as bad as 2 weeks ago.
So measured the pressure from fuel line off pump to carb….on carb end.7+ Lbs sometimes.
So I thought if I put the pump I used to run, it will be at 4 - 4.5 psi, no drips and everything will be solved.
So when I Hook up that pump, everything else the exact same, I can’t go under half throttle in neutral at the dock, because it will stall out instantly when I take the rpms away.

when I go back and look down the airhorn, the gas is dripping from the venturi’s but hardly at all. But it will run at high revs in neutral but won’t let me come back anywhere near idle…dies out way before. I can give it throttle when it starts to die and it will catch and I can increase the throttle and it will stay going, bring it back again and it will die.
To start again, put throttle down 3/4 full and turn over a few revolutions and it will catch.
Dad says my exhaust bubbles breaking on the waters surface are blacker then perfect exhaust

 

[alldodge]

The dying when going back to slow or neutral might be the shift interruptor. Has it been checked

 

[Mercruiser 120]

The dying when going back to slow or neutral might be the shift interruptor. Has it been checked

When you say check. To see if it is grounding and talking to the negative side of the coul

 

[Mercruiser 120]

If I unhook it off the coil and do everything else the same at the dock, will that be a way to test it.
I want it eventually to stop dripping when I shut the key off. That was the initial problem I wanted to fix. Everything has become worse when I went to the lower pressure pump.

 

[Mercruiser 120]

Because there is no way I could get it into gear the way it is running. So the shift interrupter doesn’t matter.

 

[Mercruiser 120]

Oh and it dies way before I bring back to slow. With the 4.5psi pump. It dies at like 2200 rpms and anything under that