sudden loss of power

[Don't Panic!]

1987 Searay 19', 4.3 OMC Cobra

This weekend I was cruising along at around 3k rpm / 30 mph and hit a wake pretty hard. Nothing unusual, but it was a definite jolt that I should have backed off for. Immediately after the first hit, the engine bogged hard. I dropped to idle and got through the set of wakes (there were three tugs going the other way together). When it cleared up, I gassed it, and the engine fell on it's face at 1500 rpm. It would idle fine, and in neutral revved up to 4k fine, but under load wouldn't pull past 1500 rpm.

I drove back to the dock no problem, about an hour at 1000 - 1200 rpm. I tried several times to gas it up, and consistently hit a wall at 1500 rpm and I backed down to idle.

So... What should I look at? Sort of feels like the jolt dislodged some crud into the main jet. I'm decent with carbs, but my knowledge is mostly single cylinder motorcycles which are simpler. I've got a Rochester 2jet on this engine, and my initial research leads me to believe there are 2 main jets, it seems unlikely both could have clogged at the same time?

I don't see anything on the engine that has obviously fell off or disconnected, all linkages and wiring look like they should as far as I can tell.

Where to start?

 

[Scott Danforth]

a carburetor is just a glorified toilet bowl.

start with compression ratio
fuel pressure
and cleaning the carb.

also being a 1987, have you serviced the points?

 

[Scott06]

What does your fuel filter look like on the inside I suspect you have a fuel delivery issue but it’s Scott outline starting with some basics

 

[Bondo]

Ayuh,.... I too, would start with inspectin' the contents of the fuel filter, in a clear container, for anything but clean fresh gasoline,.....

 

[Don't Panic!]

Sounds good. I've got a carb rebuild kit on order, will tear into it sometime next week probably. I'll check the fuel pressure and pump vacuum before doing anything just to see where it's at, but I need a new gauge as I can't find mine. Fair enough, it's been 20 years and I've moved twice since I last needed it lol.

The spin on fuel filter/water separator was replaced this spring, probably had about 100 gallons go through it since then. I have not looked at the carb mounted little filter. That will be cleaned during the carb rebuild though.

Will report back when I get parts and do some testing, Thanks!

 

[Scott06]

Sounds good. I've got a carb rebuild kit on order, will tear into it sometime next week probably. I'll check the fuel pressure and pump vacuum before doing anything just to see where it's at, but I need a new gauge as I can't find mine. Fair enough, it's been 20 years and I've moved twice since I last needed it lol.

The spin on fuel filter/water separator was replaced this spring, probably had about 100 gallons go through it since then. I have not looked at the carb mounted little filter. That will be cleaned during the carb rebuild though.

Will report back when I get parts and do some testing, Thanks!

Take the fuel filter off and dump contents in a clear container. if there is junk in there you will need to clean whole fuel system. if ok put the filter back on.