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2006 mercruiser 4.3 backfires at 2000 rpms

mcfam

New member
I have a 4.3 that starts backfiring at 2000 rpms, I have went thru the carb and checked the timing. it starts and idles great and runs up to 2000 rpms but then starts backfiring. It gets great spark, timing is right on, and it is getting plenty of fuel. What do I check now?
 
The timing control module is most likely bad........

I believe you have a thunderbolt V ignition...??? DO you know if this is so?

It should have two modules (piggy backed) attached to the distributor???

If this is so, then there are five major compnents

Cap
sensor...........inside cap, mounted to distributor inside bottom.
Rotor
timing module
knock sensor

the two modules piggy backed are, timing module and Knock control module.

Typically when you can not get past 2000 rpms it is a timing control module.

In some rare cases it can be the sensor inside the cap.

If you know of someone else with this motor set up try to swap the timing module and see if that corrects the issue.

Also how many hours of operation on the motor?
Has it ver over heated and if so how severe?

When a motor typically backfires it has two places it back fires to/from.
either the carb/intake or the exhaust

Is your back fire from the exhaust or intake/carb

Carb back fires can be a bad valve or timing issue

exhaust is typically fuel related
 
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