no revs in a Mercruiser 5.7 carb.

[mmwjr]

The compression numbers sound good, did all the plugs look about the same?

Contact Mercruiser with the drive serial number and they can tell you what gear ratio it is and be able to recommend a prop. The prop you have is wrong for this boat.

[Alvaroe46]

Originally Posted by mmwjr

The compression numbers sound good, did all the plugs look about the same?

Contact Mercruiser with the drive serial number and they can tell you what gear ratio it is and be able to recommend a prop. The prop you have is wrong for this boat.

All the plugs are look the same.
So...i have a wrong prop?
I prefer that to a broken engine

[jrsick]

A different prop may improve performance, but it won't come close to adding 1000 rpm to your WOT. You should continue to troubleshoot your engine while researching prop size.

[shrew]

Has the tachometer itself been ruled out? Are we sure it's accurate and not sticking?

Just a thought.

[Alvaroe46]

Originally Posted by shrew

Has the tachometer itself been ruled out? Are we sure it's accurate and not sticking?

Just a thought.

Hi;
It has been proven, but thank you for the idea. It could have been a cause.

Thanks

[Alvaroe46]

Hi,I replaced the wire that didn't look so good. It is not tested because of bad weather (waves).
I wil try to check it on Saturday and i will post again.

THanks

[Alvaroe46]

Hi!
This engine have any sensor or limitator?

Thanks


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[mmwjr]

Originally Posted by Alvaroe46

Hi!
This engine have any sensor or limitator?

Thanks


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Not certain as you did not tell us the year of the engine or answer my question if it has the Thunderbolt V ignition system. If it does then yes it can rev limit in safe mode if detonation is detected. You should also check for water in the gas by removing the fuel filter and emptying it’s contents into a clear jar to look for water and or sediment.

[Alvaroe46]

Originally Posted by mmwjr

Not certain as you did not tell us the year of the engine or answer my question if it has the Thunderbolt V ignition system. If it does then yes it can rev limit in safe mode if detonation is detected. You should also check for water in the gas by removing the fuel filter and emptying it’s contents into a clear jar to look for water and or sediment.

Sorry, I didn't read your comment.
Yes , it's thunderbolt. The engine's from '96.
I don't think there's any water in the gasoline.
But I'll check again.
Thank you very much.


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[donald]

You still did not answer Mikes question!
If it has a Thunderbolt V (5) then yes it could go into safe mode and have a rev limiter.
I would suggest you take your boat to a Mercruiser mechanic and have him look at it.
Don

[mmwjr]

Being a 1996 it should be a Thunderbolt V (5) and not a Thunderbolt IV (4) so it has a knock sensor that can go into safe mode and restrict rpms is it detects knocking.

[Alvaroe46]

Originally Posted by donald

You still did not answer Mikes question!
If it has a Thunderbolt V (5) then yes it could go into safe mode and have a rev limiter.
I would suggest you take your boat to a Mercruiser mechanic and have him look at it.
Don

Hi, I'm sorry if I didn't explain it properly. If it's 96, it does have the thunderbolt V.
I know this because it's on the cover
Thanks


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[Alvaroe46]

Originally Posted by mmwjr

Being a 1996 it should be a Thunderbolt V (5) and not a Thunderbolt IV (4) so it has a knock sensor that can go into safe mode and restrict rpms is it detects knocking.

Correct Thunderbolt V , As I put it before, it's written on the cover.


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[mmwjr]

Originally Posted by Alvaroe46

Correct Thunderbolt V , As I put it before, it's written on the cover.


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u

Thought so, then yes it can limit rpm.

[Alvaroe46]

Originally Posted by mmwjr

u

Thought so, then yes it can limit rpm.

Hi!!

I kept looking and on the engine cover it says thunderbolt V but on the ignition control module (attached to the exhaust manifold) it says thunderbolt IV. I think there's something weird. And there's a loose wire connector at the back of the engine. It looks like an ignition.


Thanks

[mmwjr]

Originally Posted by Alvaroe46

Hi!!

I kept looking and on the engine cover it says thunderbolt V but on the ignition control module (attached to the exhaust manifold) it says thunderbolt IV. I think there's something weird. And there's a loose wire connector at the back of the engine. It looks like an ignition.


Thanks

Can you post pictures of the module and distributor?

[Alvaroe46]

Originally Posted by mmwjr

Can you post pictures of the module and distributor?

Yes of course, tomorrow i will do it and i will post.

I suspect that the TB-V module broke at some point and now they've put in TB-IV.I don't know if it's possible or not.

The 8-pin connector on the TB-V module is disconnected and hidden behind the engine. I discovered it today.

thanks

[jrsick]

ICM and distributor picture may tell a lot. I'm interested to see if the wires from the ICM to distributor have been spliced with new connectors. May be wrong ICM.
Could you also get a picture of the distributor rotor and the metal ring attached to the underneath of the rotor?

[Alvaroe46]

Hi everyone,
because of the fxxing virus I can't leave the house. It's forbidden.
I have to wait for permission and I can go down to the port.

many thank for all of you.

[mmwjr]

Understand, take care.