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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16209
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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My 25hp mercury "big foot "outboard wont go over 4 rpm when

Customer Question

My 25hp mercury "big foot "outboard wont go over 4 rpm when throttle is engaged all way. But if i cover the intake w 2 fingers the engine accelerates and reaches 6 rpms...i replaced fuel filter. Plugs. And wires.. but no go...
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with?
Expert:  Jason replied 2 years ago.
Is this engine 2 stroke or 4, EFI or carb? If you have the serial number that would be best. Also, has the engine been sitting for a long time?
Customer: replied 2 years ago.
Peter
Customer: replied 2 years ago.
4stroke
Customer: replied 2 years ago.
It sat for 5 years
Customer: replied 2 years ago.
Got it running last year. But prob occured w rpms
Expert:  Jason replied 2 years ago.
Hi Peter. EFI or Carb, they made this engine both ways.
Customer: replied 2 years ago.
Carb
Customer: replied 2 years ago.
Serual #0t222162
Expert:  Jason replied 2 years ago.
Got it. If you are covering part of the carbs intake and the engine runs better then what that means is the carbs internal fuel jets are clogged up, and not flowing enough fuel. Which is going to be typically of an engine that sat 5 years. The proper fix here would be to have the carb cleaned ultrasonically. Does that make sense?
Customer: replied 2 years ago.
Yes and how would that be done
Expert:  Jason replied 2 years ago.
The carb comes off, gets completely disassembled, and sits in a heated ultrasonic machine for 1/2 hour to 45 minutes. After it comes out it gets rinsed with hot water, and then blown out with compressed air from an air compressor blowgun. Then it gets put back together with a new carb gasket kit, and reinstalled back onto the engine.
Expert:  Jason replied 2 years ago.
Did you have any further questions on the issue?
Customer: replied 2 years ago.
Should i take it to another shop, had some one take it apart last year and cleaned the jets manually
Customer: replied 2 years ago.
The process that tou suggest can be completed by a reputable boat shop?
Expert:  Jason replied 2 years ago.
Yeah you would really have to. On 4 stroke engines the carbs can not be cleaned by hand, not successfully anyways. The internal passageways are just to small, to small to even spray solvent into in most cases. Which is why Mercury specifies that they should be cleaned ultrasonically. If you are calling around you would want to specifically ask if they clean their 4 stroke carbs ultrasonically. If they don't, then move on and call another shop
Expert:  Jason replied 2 years ago.
Was there anything else I could do for you?
Expert:  Jason replied 2 years ago.
It looks like you logged off. If you had a further question on the issue by all means feel free to ask. If not, Just incase you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, just reply back "I rate Jason's service _______" and fill in the blank.
Questions do not lose out, so if you have to come back tomorrow or next week with follow up questions to this you still can even after doing a rating. And if I have saved you quite a bit of money, or saved you a trip to the dealer, tips are always greatly appreciated.
Thanks,
Jason
Expert:  Jason replied 2 years ago.
Good morning, just checking in, any luck?