Stalls on acceleration

[SbMolly]

My 28’ Sabre has an atomic 4, motor starts right up ( when choked), and i can ‘unchoke’ after a couple minutes. Will run at idle speed all day, and in gear cruises me around 2 knots at slow speed - ran three or four miles yesterday at this speed, no problems. But as soon as I try to give a little more gas, motor stalls. UNLESS I pull the choke again, then it will stay running at high rpms. I did some searches, but couldn’t find the likely culprits. Any ideas? Thanks.

Boat is new to me, I drained the old fuel and replaced with fresh, and replaced spin on water separating filter. May have an oil pressure problem too, or it may be the gauge, sender, or wiring.

[joe_db]

My 28’ Sabre has an atomic 4, motor starts right up ( when choked), and i can ‘unchoke’ after a couple minutes. Will run at idle speed all day, and in gear cruises me around 2 knots at slow speed - ran three or four miles yesterday at this speed, no problems. But as soon as I try to give a little more gas, motor stalls. UNLESS I pull the choke again, then it will stay running at high rpms. I did some searches, but couldn’t find the likely culprits. Any ideas? Thanks.

Boat is new to me, I drained the old fuel and replaced with fresh, and replaced spin on water separating filter. May have an oil pressure problem too, or it may be the gauge, sender, or wiring.

Clogged main jet maybe?

[roadnsky]

When is the last time you inspected your exhaust?

See HERE for other thoughts...

[JOHN COOKSON]

Molly
The carburetor has two circuits - an idle circuit* and a high speed circuit*. The amount of gas that flows in the circuits is controlled by "jets" basically pieces of metal (brass) with precision holes drilled in them.
By pulling the choke out you are making the mixture "richer" ie more fuel in the fuel\air mix. It sounds as if your engine is starving for gas when it tries to run on the high speed circuit. Also since changing the mixture ratio with the choke changes the engine's performance it indicates there is a problem somewhere in the carburetor. If a piece of crud gets into the main jet (this is the jet that meters gas to the high speed circuit) it will basically disable the high speed circuit.
My #1 vote at the moment is a blocked main jet. That having been said there are other causes off lack of power. See what others have to say.
*Not sure my names are correct..........

ex TRUE GRIT

Edit: A BIG welcome to the forum.

[SbMolly]

I have never had the exhaust apart, or checked. The boat is new to me, was somewhat abandoned by the previous owner, I took it from the marina. Never met the previous owner, but the marina mechanic did a lot of work on the boat for him.

He warned me the day I launched that the carb needed to be choked in order to run - he said he had it rebuilt for the PO, but it didn’t fix the choke issue. Before he could look into it anymore, the owner lost interest so he didn’t go any further.

So that sort of has me thinking it’s not a carb problem, even though the symptoms seem to point me in that direction. I did see the Moyer video about cleaning the jets in both circuits - may proceed with that, but not optimistic I will do a better job with the carb then the last guy who had it apart.

[edwardc]

When cleaning the jets, you must physically put a small wire through the opening. Mearly spraying carb cleaner or compressed air through it will not cut it.

[JOHN COOKSON]

THIS WOULD MAKE ME NERVOUS

May have an oil pressure problem too, or it may be the gauge, sender, or wiring.

Please start a new thread R\E the " oil pressure problem". Describe the problem in as much detail as possible.

ex TRUE GRIT

[SbMolly]

Finally got back to the boat and got the carb apart. The jets are out, and look clean as can be, hold them up to a light, and not a bit of crud. that was a bit of a surprise. Also was surprised that there was no fuel in the carb. It’s been a few weeks since I ran the motor, but did not expect the fuel to drain out. Is that normal behavior for this setup ?

The floats sound like a sleigh bell when I move them, not sure what is inside of them.

[Dave Neptune]

The floats should absolutely not rattle. They should be empty of any liquid and have no rattles. They could of had a solder job to fix a leak and some dripped inside. They need to be sealed.

Sounds like you may also have a fuel delivery problem too. Get a gage mounted to be sure. Could be a clogged filter or a failing fuel pump, it will idle but not pump enough to "run".

There are two idle ports on the same circuit, one below (slow idle) the butterfly towards the manifold and one above (hi-idle) that activates as you open the throttle did you poke them clean?

Dave Neptune

[SbMolly]

It idle fine, but when there is a load on the motor, when I accelerate, it stalls - unless I have the choke closed - then it will run ok. So seems to be running lean when above idle / vacuum drops.

Replaced all of the jets today, but ran out of time an could not take a test run when i finished. It did start right up though.

Does anyone have a link for what i would use as a fuel pressure gauge? I’m used to working on efi motors, where you just put the gauge on the shraeder valve on the rail. Not sure how I would plumb it for this setup. Thanks.

[roadnsky]

Does anyone have a link for what i would use as a fuel pressure gauge?

HERE is a common gauge that many of us are using.

[mattlamb]

I had same issue..

Great idle dies on high rpm , cleaned carb, new points, plugs, distributor cap, rotor. Same

Found it!

Under the distributor cap is the points, they sit on a metal plate, undoe screws and remove plate..

3 little fly weight's !

As they spin they move and set the timing..

Cleaned them and sprayed with penetrating oil.

High rpms now perfectaly smooth😀