No power with a 4.3LX

[SpoMonte]

First time boat owner, I have a 1993 4.3LX, ran great, did a simple tune up by replacing spark plugs/wires and cap/rotor. Removed coil because I was unable to remove coil-to-distributor wire, cleaned high voltage contact, all looked better. Starting is a little hard. With the drive not engaged, throttle only, I can get the engine to 3-4k rpm with no problem, however, when in forward or reverse I am unable to get anything over 1k rpm.

It's like the advance timing is not working. What signals the ICM to advance it's timing? Someone suggested a bad coil could cause issues like this? Since I had to remove coil to remove wire I wonder if I caused it to go bad?

Engine S/N: 0F116349

Thanks,
Nick

 

[dubs283]

It's like the advance timing is not working. What signals the ICM to advance it's timing?

have you checked/set the timing and verified that it is/isn't advancing?

you most likely have a thunderbolt ignition system which is electronic, the ignition module controls the timing advance and gets a signal from the sensor in the distributor

once you check/verify ignition components and operation your next step is to inspect the fuel delivery system

 

[SpoMonte]

have you checked/set the timing and verified that it is/isn't advancing?

you most likely have a thunderbolt ignition system which is electronic, the ignition module controls the timing advance and gets a signal from the sensor in the distributor

once you check/verify ignition components and operation your next step is to inspect the fuel delivery system

I have not checked or set the timing yet. It worked great last fall when I bought it.

It does have a thunderbolt ignition system and I saw the sensor in the distributor but I thought that is just to pulse the ignition to fire. I thought there would be some other signal to the ICM to advance the timing?

How do you set the base timing? Is there a pin or connector that I tie to ground to set base timing?

 

[MichaelBC]

I have not checked or set the timing yet. It worked great last fall when I bought it.

It does have a thunderbolt ignition system and I saw the sensor in the distributor but I thought that is just to pulse the ignition to fire. I thought there would be some other signal to the ICM to advance the timing?

How do you set the base timing? Is there a pin or connector that I tie to ground to set base timing?

With the signal of the sensor the ECU knows the rpm and adjust the timing. Just device the impulses by 6.

For a Thunderbolt IV there nothing to be set for timing adjustment. Just set it to 8° advance and that's it. With a Thunderbolt V there is one cable that has to be connected to ground for timing mode before you turn on ignition. Then the engine is set to 10° advance.

 

[SpoMonte]

With the signal of the sensor the ECU knows the rpm and adjust the timing. Just device the impulses by 6.

For a Thunderbolt IV there nothing to be set for timing adjustment. Just set it to 8° advance and that's it. With a Thunderbolt V there is one cable that has to be connected to ground for timing mode before you turn on ignition. Then the engine is set to 10° advance.

I have the Thunderbolt IV and with the absence of any other signal rpms is all that is left which is what I concluded, but I was still looking for a wire to ground to set base timing as I would do on my cars. So, this is new to me, thanks for the info.

Do you know what the rpm at idle should be when timing is set to 8° ?

 

[MichaelBC]

The idle speed for the TB V is 650 rpm. So I would also use this for the TB IV.

 

[SpoMonte]

Ok, will see what I get when I check the timing.

 

[SpoMonte]

I have an update. Replacing the coil did not improve the idle. Found a TB IV that was NOS and replaced the sensor. The timing was off by 2 degrees at 6°, so I corrected that and now runs like a champ and was able to do 50+, better than last year.