4.3 hard starting and no power under load

[Selahguy]

This one is a stumper to my boating pals and maybe someone can help. I have an 89 17' Bluewater with a new 4.3 with Thunderbolt ingnition. Rebuilt altenator and rebuilt 2GC Carb. Timed out at 8 BTDC when I had it running in the yard and will rev up but not a snap rev up. Take it out to the lake and drop the lower unit in the water and it will hardly start. I really had to help it along to get running. Got it running and warmed up and idled out to open it up. Push the throttle down and everything drops out and will only hit 12K on the tach. Opened up the dog house and the butterflys are wide open and fuel is dumping into the motor but just no power under load. Could it be the Thunderbolt amplifier causing the problem or even the HEI coil?

Thanks for any help!!!

 

[Reel Poor]

Re: 4.3 hard starting and no power under load

When was the last time it had a complete tune-up, plugs, cap, wires, rotor, fuel filters, base timing and advance timing checked, and carb adjustment?

 

[180shabah]

Re: 4.3 hard starting and no power under load

Everything RP said, plus the possibilit that the gas is either bad or contaminated with water

 

[Selahguy]

Re: 4.3 hard starting and no power under load

Thanks all for reply!! Motor is brand new top to bottom. Compression check was done on the motor stand. Gas tank drained and refilled with Premium gas with new fuel filter. Plug wires and dist cap have been checked out and are fine.

 

[springer07]

Re: 4.3 hard starting and no power under load

I also have an 89 4.3 with the same problem. I did some things and it is alot better, almost back to normal. I changed the coil that was the biggest help, also the wires that run from the key switch to the coil need to be replaced they will corrode inside and you have to have 12 volt at the coil mine only had about 7 untill I changed the wire. the only thing that I have not changed is that thunder bolt ingintion box. I think that is the problem but no one will say for sure. I think that box is actually a cdi box. I used to mess alot with quads and snowmobiles and they have cdi boxes and they control spark so thats what i'm going to try next. I'll keep you posted.