Mercruiser 7.4MPI wont go past 2600 rpm and rpm jumping

Nope. Takes 5 minutes and your back in business. If you have twins, swap it and see if it follows. I had the same exact issue. I replaced everything until I got to this one part. Make sure you clean up the mounting surface and apply the heat transfer paste that comes with the new module.
 
It's never the coil...but you'll have a spare after the purchase.

Or... you can test the coil with the procedure outlined in the TSM
 
West32 said:
Nope. Takes 5 minutes and your back in business. If you have twins, swap it and see if it follows. I had the same exact issue. I replaced everything until I got to this one part. Make sure you clean up the mounting surface and apply the heat transfer paste that comes with the new module.
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Going to go pick up that module tomorrow morning. Does your engine have a spark control module ? I cant find it on mine.
 
 
Yes. Mine would idle fine for quite a while. It would even run good for 2 or 3 miles at 3200 rpm, then it would act up until the module cooled off. It's very common for these to go bad. Typically the heat transfer paste drys out and it can't get the heat out of the module, then they go bad
 
West32 said:
Yes. Mine would idle fine for quite a while. It would even run good for 2 or 3 miles at 3200 rpm, then it would act up until the module cooled off. It's very common for these to go bad. Typically the heat transfer paste drys out and it can't get the heat out of the module, then they go bad
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sees like its still has the issue with a cold engine sometimes. But however after running it for a while it would be hard to start it back up until the engine cools off or even sometimes i cant get it to start.
 
Do you have twin engines? Swap the modules and see what happens
 
Yesterday I went out and purchased a new ignition module that goes under the distributor cap thinking it may resolve my problem but still have the problem. It did seem to get a little better because now it will at at least plain out and hit 3400 rpm as to before it only got up to 2600rpm. I also purchased a new coil that goes under the distributor cap and will replace that soon. I am going to pull the fuel pump out sometime next week and make sure there are no leaks and replace all the orings. I don't have a live data scanner. Just a code reader but no codes come up.
 
West32 said:
Yes. Mine would idle fine for quite a while. It would even run good for 2 or 3 miles at 3200 rpm, then it would act up until the module cooled off. It's very common for these to go bad. Typically the heat transfer paste drys out and it can't get the heat out of the module, then they go bad
Click to expand...

That module did not fix it for me, however it does seem like it got a little better. The boat will plain out now to 3400 rpm vs before it only got up to 2600rpm.
 
Before you do anything, you should do a compression test. Pull all the plugs, Put the throttle wide open and check each cylinder. This will confirm you don't have something more major inside before you purchase the tune up parts. I would then go ahead with your plan of replacing the coil under the distributor rotor. I would also look at a complete tune up. Cap, Rotor, Plugs and Wires. I could be as simple as a fouled Spark plug from the module being bad.
 
West32 said:
Before you do anything, you should do a compression test. Pull all the plugs, Put the throttle wide open and check each cylinder. This will confirm you don't have something more major inside before you purchase the tune up parts. I would then go ahead with your plan of replacing the coil under the distributor rotor. I would also look at a complete tune up. Cap, Rotor, Plugs and Wires. I could be as simple as a fouled Spark plug from the module being bad.
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Right so that is what i mentioned in first post. I did the full tune up and checked compression. Everything is good
 
If that is the case, I'd verify that all of the cylinders are firing in order. Make sure you have the firing order correct with your wires. I've had 2 wires crossed once and it seemed to run fine, but lacked full power. Check your plugs and see how they look. If any look odd compare to the others, verify your wires are correct.
 
Bigdog98 said:
Nope, have not changed them yet.
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I had broken a fuel injector a few years ago while changing manifolds and the ECM harness was hanging and cracked the injector. It was doing the same symptoms as you. Maybe check them where connectors are.
 
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