Help with Diagnosis needed.
 

After running well the last several times out. I developed a stuttering and dying of one engine when tying to get up on plane (under a load).

In Nuetral, I hear a feint miss. I can rev to 6K out of gear. Can't make to 2K rpm under load. Fuel pressure is constant (8lbs). Plugs are not fouled but moist. I changed Dist. cap, cleaned up rotor, made sure mechanical advance weights were clean and lightly lubed and operational. Plug wires in good shape and connected etc.

I am suspecting a faulty coil or ignition box. Both are Crane units. Tomorrow is my last day before insurance lay-up begins. any suggestions to check or test before I start swapping out parts?

What set up are you running, and i would ease up on the 6 k revs in neutral or your problems will be bigger.

I only goosed it to little more than 1/2 throttle and it spun up there ever so briefly. Had to see what happened out of gear.

It is a 1250 dominator on 604 inches. Crane HI-6 marine ignition, Crane Fireball coil. Nology wires, NGK plugs. Holley Dominator fuel pump.

It has run well up to now.

2112,

I had the same problem. Port engine would run like a raped ape in neutral and under load. Starboard would run at high RPM's until I put it under load, then it only went to 2k RPM's. My problem was a cracked head. You might want to check that or your head gasket. I'm not saying that's what it is, just what I had is simular to what I have read here.

Good Luck,

Sulfur 1

Man I hope not. No water in oil, overheating etc. Anything is possible.
I did adjusted the valve lash but it ran fine afterward. Problem started after a non eventful 3-4000RPM cruise.

Could be valve springs. Take the valve covers off and look for broken springs. You can also swap your HI-6M's and see if the problem is still there.

Dave

Hi,

Are all 8 plugs in the sour engine moist? If so, I would also suspect ignition issue - at first I thought sticking timing advance weights, but you've checked them....try swapping the coils and see if the issue follows the coil.

yes all are a little moist, a couple a little more so. They are the typically rich runners on my intake manifold.

Good suggestions. I will do both tomorrow.

When you say that the fuel pressure is constant, do you mean that it is constant also under load, in the fault situation?

Yes under load.

Sour side coil is pretty warm. I am not running long enough to get it hot. When I let it cool for 5 minutes she fires right up like nothing wrong.

It is so foggy right now I can't get out to check things out.

BTW everything is new but the coils. I have been using them a few years. Dumb I know. Dumber still is the fact that it is one of the only things I don't keep a spare of.