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2007 Mercury 150 EFI (2-stroke) stumped my mechanic

C

corbett79

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#5 & #6 cylinders are not firing. I purchased this boat from friends who barely used it and it sat for several years. Typically after a service, it will run amazing. However, after a few more times on the water, it starts to bog. Now these two cylinders aren’t firing and I took it to my mechanic. Mechanic spent 3 hours on the computer. According to him, it only has 112 hours on it! Mechanic replaced the fuel regulator, swapped around the spark plugs and coils. Mechanic’s boss thinks it is injectors, but mechanic thinks it could be a sensor. I guess their computer doesn’t pinpoint the issue and they recommended I take it to a Mercury dealer (I didn’t realize they weren’t a certified Mercury dealer). Any ideas are appreciated before taking it to the next mechanic.
 
First of all check to see if It has spark to those cylinders, needs to be 7/16 or more of spark then check the compression of all the cylinders, they should be within 10% of each other and while the plugs are out look in at the cylinders through the plug hole with a bright flashlight to see if there is a lot of scoring on the walls. Some things can be diagnosed with a computer but basic engine health is better checked manually.
 
You can check injectors easily here.....how? Crank it over with plug wires off and/or shorted to ground. Then remove plugs to see if they are all wet. I don't have a computer....except the one between my ears. That one has 5 available inputs: sight, sound, smell, taste, feel.
 
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I purchased this boat from friends who barely used it and it sat for several years.
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This is your problem...The fuel system needs to be flushed,VST cleaned and the injectors and ECU sent to Brucato to have tested/cleaned and balanced. Cannot test these by cranking engine as even if spraying a lil plugs will be wet. Need to check bottom cylinders as if running lean they can scuff due to lean fuel supply.
 
Makes sense, Pappy. While working in the Philippines on Raquel's 98 F150 4.6 litre, I found her driver had gotten watered down fuel. Rust inside tank, lines, rails, injectors. The Ford dealer there are thieves. Wanted $120 per injector. I really should report them to Ford USA. I'll NEVER buy another Ford in Davao City. So I cleaned rust from injectors and made a tester to monitor trigger pressure and allow me to examine spray pattern. $120 bucks is 2 weeks wages over there. Found I could recover 5 of the injectors. Had my brother get the rest from Rock Auto. He sent them to me there for 25 bucks each....DELIVERED to mail center in Davao. So testing injectors is not impossible to do yourself with a little intelligence and ability. I triggered them with 4 volts while applying 60 psi behind a line with fuel in it. Even with my wife a Philipina, that dealer will try to screw you just because they know you got a pocket full of cash.
 
faztbullet said:
This is your problem...The fuel system needs to be flushed,VST cleaned and the injectors and ECU sent to Brucato to have tested/cleaned and balanced. Cannot test these by cranking engine as even if spraying a lil plugs will be wet. Need to check bottom cylinders as if running lean they can scuff due to lean fuel supply.
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Appreciate your feedback.
 
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