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7.4 MPI with Bravo 3 wont make power.

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robert76

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1999 7.4 with bravo 3 will not make power. Will not go above 3700 rpms under load. Not a prop issue, compression is great, plugs are new. Fuel filter changed a week ago.
 
What are the chances that its an injector issue? Could it be from the ethanol in the gas, it ran fine before it went into dry storage last year. I do not think its a fuel pump issue, the rail has pressure.
 
If the filter is a fuel/water separator, dump out most of the fuel and fill it w/SeaFoam. Start the engine and run it. It will smoke--that's OK. Repeat if necessary.
 
seafoam is amazing mystery engine cleaner and treatment, it will bust up any junk in the engine, you can also add it to your crank case, i used it in truck one time to quiet some noisy sticky lifters, i think napa carries it, try it out its great stuff
 
robert76 said:
1999 7.4 with bravo 3 will not make power. Will not go above 3700 rpms under load. Not a prop issue, compression is great, plugs are new. Fuel filter changed a week ago.
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rob60 sounds like I have the same problem 97 7.4 bravo 3 runs great planes out just want turn over 3300 rpm was turning 4600 last season help please
 
rob60 Ihave 7.4 bravo 3 it runs good but want turn over 3300 rpm last season it turned 4600 I ran the boat (252br formula) this year dose good planes off and will run 36-40 mph should run 53-56 @4600 I need help thanks rob 60
 
rob60:

What exactly have you done to resolve the low RPMs issue? Is the hull clean? Is it trailered or kept in the water? What and when was the last PM?
 
rob60;
If you leave the boat in the watr full time, what are the chances you have a hull leak and water is getting into you sub-floor foam?
Two or three thousand extra pounds of water makes a huge difference in performance.

Rod
 
sounds like you need to run the boat on a 6 gal. aux gas tank with fresh gas, if that does not do it like Rod said, if thats the case that would suck but have seen that before also, nothing a good barrier coat would not cure just takes forever for the boat to dry out.
Like guy said, I can't say enough good about seafoam either.
 
Just your wallet. Fill up the water sep. filter w/it, put 1/2 of a can in the engine oil and run it a few minutes at 1500 RPMs. Shut it off for a few hours, change the engine oil and filter and then run it normally. It will smoke like an old diesel until the Seafoam is all used up but the injectors, rings and valves will be clean.
 
my boat stays on a lift & on the trailer in the winter bottom looks like new. I have check throttle new plugs,rotor,cap,wires,filters,props look like new to.took it to lake wylie marine to they use not sure what to do
 
This post could very well be your solution.

Intelleq
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Re: Mercruiser 350 MEFI power issue help needed (2000 Maxum 3300SCR)[/h]
Turned out to be an intermittent electrical connection between 2 of the injectors and the wiring harness. The injectors appeared to be firing normally at idle and low RPM but were misfiring or not firing at all at higher RPM. The fix was simple, clean the connector contacts.​
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