MERC 200L carb not reaching WOT

[rangerfscott]

Good morning. i have a 2002 200L carbureted engine mounted on a 19.5 ft stratos bass boat. the last few times i have been out fishing i can't get the boat/motor to run wide open. typical WOT for my engine is 5600rpm. btw i have a hot foot throttle. when i start out and get on plane no problem really; seems to be a lil sluggish at times though but once there it runs good but with the pedal mashed all the way it will only do around 4600rpm but if i gently ease off the pedal slightly the engine starts picking up speed up to about 5000 to 5200rpm. sometimes i can quickly mash the pedal all the wy again and it will gain another 100 or so rpms that way. but i never reach WOT and my max speed by GPS is only hitting 56 -58mph whereas i normally run mid to high 60's. now my thinking is the carbs so i took them off cleaned and rebuilt them. same thing. no change rebuilt the fuel pump next; also no change. thought maybe shutter plates weren't opening all the way or maybe going to far; had my daughter mash pedal to the floor repeatedly while i examined the shutters and the cable. shutters looked to be perfectly level and cable was pulling throttle to wide open stop screw on engine. i am searching for clues now. i have solid blue spark jumping over 7/16 inch on all cylinders. changed spark plugs and checked gaps and ran it. no change. and plugs all looked the same with just light hazing. so what next? i have a dva adapter being delivered monday. should i test my stator, trigger, switchboxes etc..? any ideas are greatly appreciated. thank you.

 

[rangerfscott]

sorry. i didn't know it posted 3 times!! i got an error message the first 2 times.

 

[Chris1956]

I think a compression test is the first test. Look at the spark plugs hen you remove them for the test. They should be light to dark brown. White or black or real clean would indicate an issue.

 

[rangerfscott]

compression on all cylinders is running 120 to 130psi. and the spark plugs are all have just a lil hint of darkish brown to maybe a little black but not oiled or fouled at all. i put a new stator on this motor in august of 2012. it is acting similar to what it did then. i am reluctant to think that it has gone bad already but i read somewhere that a weak or faulty battery could cause one to have a short life and i did have to replace my cranking battery in late february due to it not taking/holding a charge enough to run my electronics and livewells and crank the engine every few minutes to move to a new spot.

 

[enginepower]

Sounds like you are starving for fuel. My dad had this happen to his 200 merc and it ended up being the fuel lines collapsing and unable to get sufficient flow. There are special fuel hoses required for the ethanol based fuel these days and older boats just aren't equipped with it.

 

[rangerfscott]

yes i have already changed over to the new etanol safer lines from the mercury dealer about 2 years ago. it was a long one piece unit with the ball clamped in the middle. having said that i do wonder if it is possible that the line could be weak somewhere and closing up under full throttle pressure. i haven't conducted a full pressure fuel pump check as of yet but i think i will this week while i am at the lake. i can tie the boat off really good to the dock and put my vacumn guage into the system and run the motor at full throttle to check for restrictions. maybe that is it since it does surge sometimes when going down the lake.

 

[andrewcoon]

Male sure your carb jets ate clean, had the same problem on several outboards. That's pretty cool we have the same motor, haven't been able to find a whole lot of info..

 

[Dukedog]

Next time your out when ya push on tha gas and nothin' really happens push tha key in for a few seconds..............

 

[rangerfscott]

ok i have a new problem discovered that i think may ultimately be the biggest issue. i got my dva adapter and meter all set up and tested all my ignition components. everything tested within spec except my battery charge wires from my stator to the rectifier/regulators. voltage was supposed to be withing 1.5 volts on each set. well one set was only about .75 difference but the other pair was steadily around 4v different from each other. i swapped the leads and retested and the problem follwed the same wires. so that told me i had a problem with my stator. but while running it i noticed there was water leaking from the back of the motor. upon more inspection i found a missing bolt from the bottom of the exhaust plate cover and a piece of gasket hanging out the bottom of the plate while the motor was running water was steady coming out off that area. now my question to you guys is what problems is that causing and is it possible that with the engine tilted down in the water when i am fishing and i crank the engine couold water actually be sucked into the motor if there is water inside the cowl area? anyway compression is good as stated before, and the new spark plugs didn't look water washed or that they weren't firing but i haven't run it much since i put them in but all have fired some. anyway again thanks for the help; i appreciate it and gladly seek the help of more knowledgeable men than myself.

 

[rangerfscott]

oh and dukedog you are correct about the water pressure i think. i am pretty sure that gasket is causing me to lose pressure to some extent although i have been maintaining right around 10psi when running.