Port Engine Power Loss

[ready123]

To understand this.... Do you run with blowers on all the time while underway?
I turn them off once up to cruise...

[djmair]

We are looking for something obscure as I don't believe the issue is with the gas, carbs or distributor. The message about the blowers is interesting as the timing for the problem is about 20 minutes out on the lake. My International has the house battery combination on the port side and I always run the blower prior to starting. I do shut it off when I am underway. I can noticeably see the current change on my meter when I use it. I don't suppose the changing of this is a major issue and will see about it hopefully this weekend. I must say that I am somewhat on the side of the old salts on this but stranger things have happened

Thanks for all the input. Got to get to a conclusion as she hits the hard soon.

[stoutner]

Anti Siphon valves clogging up with gummed up gas. Probably have gummed up gas in your tank and it is breaking loose and clogging up that anti siphon valve. I have had that same exact problem that you are having all year and every time it is that valve clogging up with old gas residue. I clean it out and the problem goes away...for another 20 minutes until it clogs up again.

[Scorpion07]

To understand this.... Do you run with blowers on all the time while underway?
I turn them off once up to cruise...

Didn't matter on or off. That was the stumper. I do shut them off on plane.
My thoughts are that being 35 years old they shorted out inside the motors somehow?
If that's not possible, maybe the lower amp draw of the new blowers masked some other condition?

[ready123]

Anti Siphon valves clogging up with gummed up gas. Probably have gummed up gas in your tank and it is breaking loose and clogging up that anti siphon valve. I have had that same exact problem that you are having all year and every time it is that valve clogging up with old gas residue. I clean it out and the problem goes away...for another 20 minutes until it clogs up again.

+1

[larryeddington]

DJMAIR - Did the issue every get resolved before setting on the hard? Might be helpful for the rest of us to know solution if solved.

[djmair]

The situation has yet to be resolved. Going out 1 more time this week before being put on land. Hopefully will be able to check out voltage.

[Cmount]

I am far from a mechanic...but let me tell a little story. A friend of mine has a 34 Silverton...in the spring he changed his distributors out to electronic. Now he set the timing on the two engines the same...he thought they should be and he is actually a mechanic. So, not to the extent of your issue, but he had substantial power loss in one of the engines...turns out that the reverse rotation engine actually needed to be set the opposite way...not even sure what that means, but top dead center was forward on one and backward on the other. Probably means nothing, but thought I would mention it.

He found it by playing with the distributor as he sat at idle at the dock...

He also found a ground that was not the best, but with these two things now has full power again.

[Big D]

.....A friend of mine has a 34 Silverton...he is actually a mechanic....

A marine mechanic would know this or is he an auto mechanic? There are several differences that an auto mechanic would never run into in their trade. He'd really be scratching his head on an older Chris Craft with the prop shaft running off the front of the engine. Timing it off the cylinder you think is number 1 can be pretty puzzling for someone not familiar with that application! Love watching them try though!

[hanybop]

here is something to look at, check your charging system if the generator or voltage regulator is mal-functioning the engine will start to lose power after 20 minutes or so running only on battery power, and start to sputter for not having enough juice to drive the coil pack I have had this happen in a car, and you maybe miss this as when you get back to shore you plug into shore power which will automatically fire up the battery chargers, also check/replace any wire connected to the coil pack something could be worn and break connection once heated up had that issue on my madden voyage this summer ,try switching both the generator and voltage regulator over from the good engine and see what happens

Good luck and I hope this helps Paul

[hanybop]

just popped into my head, here's an add-on to my previous post, get a good pair of booster cables and connect the two engines together, did this myself this summer when one of my generators failed, and go for a run and see what happens, or heres a quick one start the engine and pull the battery cable off the engine should keep running, and something to consider is after your 20 minute run and you deplete you batteries, you said the house batteries are run from the port engine, those deep cycle batteries will rebound after sitting for half an hour allowing you to start the engine again and supplying the fuel pump enuf power to run for a little while, you said you can see the power draw with the blowers on, is it negative amps? what you should see is the amps to the positive side showing a charge, anything negative is bad

let me know how you make out

[prowlersfish]

.....A friend of mine has a 34 Silverton...he is actually a mechanic....

A marine mechanic would know this or is he an auto mechanic? There are several differences that an auto mechanic would never run into in their trade. He'd really be scratching his head on an older Chris Craft with the prop shaft running off the front of the engine. Timing it off the cylinder you think is number 1 can be pretty puzzling for someone not familiar with that application! Love watching them try though!

X2
If I remember Chris Craft did that to reverse the direction of the prop ? You would find one engine pointing north the other south so to speak . Now Owens with their wonderful Flagship engines would have both normal and reverse Turning engines turned around running off the front of the engine .