Low power under heavy load

[Mark Harvey]

I am new to the group and my boat so please bear with me. I bought a 2001 Monterey Edge 180. It’s a 18 1/2 bow rider with a 3.0 mercruiser by gm. When I bought the boat and put it in the water I notice that when I start it, It starts rough and shakes,has a bit of a rich odor of gas and the boat smokes for about 10-15 sec then clears and idles smooth. When I idle out of the marina it idles smooth but when I get past the no wake bouy and slam the throttle down, it first feels like it stalls or shuts off, then all of a sudden it starts accelerating but struggling to get on plane. Once it does though, I am able to throttle back, and trim up and stay on plane. The boat fails to reach top speed and rpm, 3600 rpm wot and 33mph wot. I understand that may be in the prop, it’s a 19 pitch but the real concern first and foremost is the poor acceleration. The boat has set for a few years before I bought it. I have tried seafoam in the gas and down the carb, I have compression tested the motor and got 150 psi in each cylinder. I’ve installed a distributor cap and rotor, plug wires and plugs. New water fuel separator filter. New prop. I don’t want to keep throwing parts at it but ultimately want it to run right. Any thoughts on where to go next? I’m thinking fuel issue/fuel delivery or carburetor or questioning if timing could possibly be the issue. Thanks in advance!

 

[alldodge]

Would need a serial number to verify but being a 01 I would guess it has a TKS carb. Your issue soulnds like it needs a carb rebuild

What do the plugs look like?

 

[Mark Harvey]

Would need a serial number to verify but being a 01 I would guess it has a TKS carb. Your issue soulnds like it needs a carb rebuild

What do the plugs look like?

 

[Mark Harvey]

I have put new ones in. These are the old ones.

 

[alldodge]

Being the old ones there not bad, tad rich but ok

The boat has set for a few years before I bought it.

Have you run the boat enough to burn up most of the old gas.? Old gas doesn't get better with snake oil (sea foam or other), just need to remove or burn enough to get rid of it.

 

[Mark Harvey]

The engine serial number or the carb number?

 

[Mark Harvey]

Being the old ones there not bad, tad rich but ok



Have you run the boat enough to burn up most of the old gas.? Old gas doesn't get better with snake oil (sea foam or other), just need to remove or burn enough to get rid of it.

I’ve run about 4 full tanks thru it now

 

[alldodge]

Motor

 

[Mark Harvey]

Motor

I can grab it tomorrow.

 

[Scott06]

Carb rebuild is likely needed
make sure choke is fully opening when it is warm

verify the new fuel filter u installed are still clean (that there was no residual crud in fuel system)

measure fuel Pressure while running at speed

with a 19” prop you should be able to get up to 4600 rpms and like 38-40 mph lightly loaded

I don’t think this will be a tks carb as my 2004 didn’t have one yet

 

[Mark Harvey]

Carb rebuild is likely needed
make sure choke is fully opening when it is warm

verify the new fuel filter u installed are still clean (that there was no residual crud in fuel system)

measure fuel Pressure while running at speed

with a 19” prop you should be able to get up to 4600 rpms and like 38-40 mph lightly loaded

I don’t think this will be a tks carb as my 2004 didn’t have one yet

I am going to snap a picture of the carb, number on the carb, and the engine serial number later today. Hopefully someone will be able to confirm what carb it is so I can get a rebuild kit coming. Is there any other filters between the tank and the carb other that the fuel filter? Also in regards to your question about low fuel pressure, what potentially could cause that? Thanks!

 

[Scott06]

I am going to snap a picture of the carb, number on the carb, and the engine serial number later today. Hopefully someone will be able to confirm what carb it is so I can get a rebuild kit coming. Is there any other filters between the tank and the carb other that the fuel filter? Also in regards to your question about low fuel pressure, what potentially could cause that? Thanks!

If the carb has a choke it is a mercarb. If it has no choke it is a TKS. Both share a common lineage from the rochester 2 jet.

If it is a mercarb they have two different style accelerator pumps, you have to get the right one or order a kit that has both ( Mikes carb parts sells them)

on a 3.0 there is a filter in the bowl of the fuel pump and a screen in the carb inlet. This would just be a quick check of debris and water. Only other thing between fuel tank and carb is the antisiphon valve that is usually right on top of fuel tank and can get stuck closed or not open fully starving fuel flow.

Fuel pressure should be 4-6 psi at WOT, you may have to rig up a T to test. Thngs that can cause low fuel pressure are the pump obviously, a clogged fuel tank vent, stuck anti siphon valve, debris in lines and filters clogged. Just easy to check before you tear intot he carb.

Since you said you did the ignition components, unless the firing order is off (would think you get a backfire or serious miss) symptoms point to carb rebuild given boat age an the fact that it sat.

 

[Mark Harvey]

If the carb has a choke it is a mercarb. If it has no choke it is a TKS. Both share a common lineage from the rochester 2 jet.

If it is a mercarb they have two different style accelerator pumps, you have to get the right one or order a kit that has both ( Mikes carb parts sells them)

on a 3.0 there is a filter in the bowl of the fuel pump and a screen in the carb inlet. This would just be a quick check of debris and water. Only other thing between fuel tank and carb is the antisiphon valve that is usually right on top of fuel tank and can get stuck closed or not open fully starving fuel flow.

Fuel pressure should be 4-6 psi at WOT, you may have to rig up a T to test. Thngs that can cause low fuel pressure are the pump obviously, a clogged fuel tank vent, stuck anti siphon valve, debris in lines and filters clogged. Just easy to check before you tear intot he carb.

Since you said you did the ignition components, unless the firing order is off (would think you get a backfire or serious miss) symptoms point to carb rebuild given boat age an the fact that it sat.

There is no miss or any backfiring, just that stumble on acceleration as well as low rpm at wot and mph is low. I will start with what you suggested and go from there. Thanks for your suggestions.

 

[Mark Harvey]

Motor

L657718

 

[alldodge]

Has Merc carb
https://www.mercruiserparts.com/bam/subassembly/30910/2330/70

 

[Mark Harvey]

If the carb has a choke it is a mercarb. If it has no choke it is a TKS. Both share a common lineage from the rochester 2 jet.

If it is a mercarb they have two different style accelerator pumps, you have to get the right one or order a kit that has both ( Mikes carb parts sells them)

on a 3.0 there is a filter in the bowl of the fuel pump and a screen in the carb inlet. This would just be a quick check of debris and water. Only other thing between fuel tank and carb is the antisiphon valve that is usually right on top of fuel tank and can get stuck closed or not open fully starving fuel flow.

Fuel pressure should be 4-6 psi at WOT, you may have to rig up a T to test. Thngs that can cause low fuel pressure are the pump obviously, a clogged fuel tank vent, stuck anti siphon valve, debris in lines and filters clogged. Just easy to check before you tear intot he carb.

Since you said you did the ignition components, unless the firing order is off (would think you get a backfire or serious miss) symptoms point to carb rebuild given boat age an the fact that it sat.

If the fuel pump was bad, or going bad, could it also produce the symptoms I’m having?

 

[Scott06]

If the fuel pump was bad, or going bad, could it also produce the symptoms I’m having?

Yes but so could plugged carb, bad accelerator pump so test first . start with filters see whats in them …

 

[Mark Harvey]

Yes but so could plugged carb, bad accelerator pump so test first . start with filters see whats in them …

Ok, thanks.