3.0 Power issues

[tjb1231]

I have a 1989 3.0L

The boat was last run about a month ago and the only issue was some slight missing at lower RPM's. But otherwise I had plenty of power to pull tubers with people on the boat.

Fast forward to this past weekend I took the boat on a big trip and experienced problems.
Very little power at WOT
Missing at lower speeds
Would not plane out most of the time

I added Seafoam and the problems went from all the time to most of the time. Towards the end of the trip i would give it full throttle and then it felt like a delay then power would kick in sometimes. Once at cruising speed it ran great. If I came off plane and then tried to go back on plane sometimes there wasn't any power and it would not plane out.

Things I tried
Visually inspect carb and fuel liines - looks good
Spark plugs and wires look good and are 2 years old
The fuel filter in the fuel pump looks good and so does the mesh one going into the carb
The carb was rebuilt 5 years ago
I ran through about 20 gallons of gas with this issue on fresh gas

Engine starts and idles fine

I do not have access to a timing gun or compression tester. But if people tell me these things are necessary I will purchase them.

Some other items that may or may not be related
Tachometer is all over the place. Sometimes it's accurate and sometimes its thousands of rpm's off
When I winterized it, I put a new 140 thermostat in it. Should it be 160 thermostat?

Thank You

 

[bonzoscott]

Re: 3.0 Power issues

Sounds like just a general tune up. Points, condenser, rotor, and cap. Just slight missing one month ago was just enough to char the points. You may get away without timing, just adjust the points right. Sounds like you're getting fuel. 140 thermostat is good. Can't speak on the tach except clean connections. The intermittent plane, not plane sounds like accelerator pump in carb. Try the tune up first and if still hesitating, carb build.

 

[tjb1231]

Re: 3.0 Power issues

Sounds like just a general tune up. Points, condenser, rotor, and cap. Just slight missing one month ago was just enough to char the points. You may get away without timing, just adjust the points right. Sounds like you're getting fuel. 140 thermostat is good. Can't speak on the tach except clean connections. The intermittent plane, not plane sounds like accelerator pump in carb. Try the tune up first and if still hesitating, carb build.

Thank you for your response. I went and looked at my motor and it does not have a distributor, it has an ignition coil setup and I am not sure if any parts are serviceable. I am not sure of this setup.

 

[Chef Shawn]

Re: 3.0 Power issues

Test the coil first, they can be hit and miss. Just because you can feel the oil shaking doesn't mean they are good. Also, disconnect the tach and give it a run in the water (not on muffs) I've read on here a shorted out tach will cause hesitation and sometimes misfires, which could be your lack of power.

 

[dswi]

Re: 3.0 Power issues

Pictures might help...
I had the same issue with my 1989 Alpha 1 3.0 engine.
Changed the points and set them (with a dwell meter) (about $40), timed the engine, and changed the plugs and the engine worked great after that.
I am pretty sure you have a distributor, but could be wrong...Where do the spark plug wires plug into?

Gotta get the tach working though. Check connections on the back.
I believe most dwell meters have a RPM option also.

You must set dwell before you time the engine...

 

[tjb1231]

Re: 3.0 Power issues

I am not near the boat and cannot take pictures right now but the plug wires do not connect back to a cap. They plug into a module that has 4 places for the plug wires and has some electronics sealed in a gel. This module is flat and only has four connections to it and not a center connection for an ignition coil. In the service manual I found they call this an ignition OCIL and is unlike a typical ignition coil that is a cylinder. The service manual does not name the type of ignition system it is. Then some wires connect to a module that is called a Control unit.

I have replaced a cap/rotor/coil in previous cars and know that setup but I don't know what this setup is.

I will work on tracking down the tach wires and cleaning them. For some reason on the timing of this, the tach started malfunctioning around the same time.

 

[tjb1231]

Re: 3.0 Power issues

OK it looks like I have the DDIS on my boat.

I found a wiring diagram for the DDIS system but it does not show where the tach sensor is located on the motor. Does anyone know? Or do I actually start troubleshooting at the tach gauge in the dash?

This could be a fun one to troubleshoot, wires go all over the place.