Hondaman74
Recruit
- Joined
- Jul 14, 2019
- Messages
- 4
Good Morning everyone. I recently purchased a 1988 Mark Twain super clean boat. Has a 4.3 Mercruiser in it. Got it on the water last weekend and would only go about 3200 RPM max barely planed out, running rough then eventually died running rough. Brought it home and did the following to it.
1. Spark Plugs
2. Cap and Rotor
3. Wires
4. Water Pump, it was making noise
5. Fuel Water Separator filter
I bought a carb rebuild kit but felt the running problem was ignition related. After installing all the parts I timed it to 8 deg. starts right up and idles good, revs in neutral well. So we got it back on the water yesterday and it will not go over 3,000 RPM sounds like its laboring, no more opting, spitting, or dying anymore, runs good but under load has no power won't plane out won't go over about 8 mph, super dog.
So we got it back home checked timing again, we even adjusted it on the water manually did not make a difference trying to manually advance it while running. So now we are left with three options
1. Carb problem but does not seem like a carb problem. It has a electric fuel pump installed
2. Exhaust plugged
3. Poor compression
We pulled the passengers manifolds yesterday looking at the flap and manifold didn't see anything still need to pull the driver side to see if flap is OK. I am hoping its in the exhaust.
The way it runs I have a hard time believing compression is a problem, but once I get both manifolds off I will check this maybe today.
Don't feel its carb problem, carb seems to be dumping fuel when running under load but just seems bogged down.
Anyone have any thoughts on this. Some other technical info. 1.84 outdrive gear ratio, 19 pitch prop.
Any ideas would be great, thanks.
Also having some weird electrical problems with gauges that I will post about after this but gauges flutter constantly when key on with fuel pump so I isolated pump with relay and its better but still flutter, gas gauges needled is all over the place doesn't to sit still if you think this could be related
Thanks everyone
1. Spark Plugs
2. Cap and Rotor
3. Wires
4. Water Pump, it was making noise
5. Fuel Water Separator filter
I bought a carb rebuild kit but felt the running problem was ignition related. After installing all the parts I timed it to 8 deg. starts right up and idles good, revs in neutral well. So we got it back on the water yesterday and it will not go over 3,000 RPM sounds like its laboring, no more opting, spitting, or dying anymore, runs good but under load has no power won't plane out won't go over about 8 mph, super dog.
So we got it back home checked timing again, we even adjusted it on the water manually did not make a difference trying to manually advance it while running. So now we are left with three options
1. Carb problem but does not seem like a carb problem. It has a electric fuel pump installed
2. Exhaust plugged
3. Poor compression
We pulled the passengers manifolds yesterday looking at the flap and manifold didn't see anything still need to pull the driver side to see if flap is OK. I am hoping its in the exhaust.
The way it runs I have a hard time believing compression is a problem, but once I get both manifolds off I will check this maybe today.
Don't feel its carb problem, carb seems to be dumping fuel when running under load but just seems bogged down.
Anyone have any thoughts on this. Some other technical info. 1.84 outdrive gear ratio, 19 pitch prop.
Any ideas would be great, thanks.
Also having some weird electrical problems with gauges that I will post about after this but gauges flutter constantly when key on with fuel pump so I isolated pump with relay and its better but still flutter, gas gauges needled is all over the place doesn't to sit still if you think this could be related
Thanks everyone