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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15684
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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1986 mercruiser 230 hp won't rev past 2500 rpm. After going

Customer Question

1986 mercruiser 230 hp won't rev past 2500 rpm. After going about a mile the boat runs perfect all day! Rebuilt the carburetor,distributer,new wires and plugs,new fuel pump,new fuel filter,checked fuel tank pick up tube for cracks,pumped out old gas,no water in it. filled with new gas.changed gas rubber hoses.Choke is working!
Submitted: 11 months ago.
Category: Boat
Expert:  Jason replied 11 months ago.

Hi Ronald, my name is Jason.

What is the history on this engine, have you ever personally seen it run correctly?

What is the serial number on the engine?

Customer: replied 11 months ago.
I have owned this boat since 1989! Ran great until this year! Don,t have serial number with me! Boat is at my cabin!
Customer: replied 11 months ago.
1986 searay 23 foot
Expert:  Jason replied 11 months ago.

Did you have any general or direct questions that you specifically want me to answer. Or did you want me to tell you what I think so far, without having a serial?

Customer: replied 11 months ago.
Tell me what you have so far!
Customer: replied 11 months ago.
ecked for loose wires on instrument panels and engine and cleaned ground wires.
Customer: replied 11 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 11 months ago.
Are you still with me?
Expert:  Jason replied 11 months ago.

I'm here, sorry for the delay, (as you are probably aware) we do offer phone service, I have been on the phone for the last 20 minutes with another client.

Expert:  Jason replied 11 months ago.

The engine needs 3 things in order to run correctly, it needs compression, timed spark ignition, and the proper ratio of fuel to air.

Compression isn't something that changes, you either have it or you don't, so that won't be the issue. The engine is either not advancing the ignition timing (if it's not advancing it won't make power) or it's starving for fuel.

What I would do if you brought this to me is first duplicate the problem. Then, when it's not making full power I would check to make sure the timing is advancing as it should by hooking up a timing light to the engine, and then snapping the throttle a few times and see if the timing advances or not. If it doesn't advance.... If this engine has points ignition the weights are going to be frozen up from rust. If it has electronic ignition, the ignition control module (which is what controls timing advance) is going to be bad.

If the timing is advancing.... Then it is going to be a fuel problem. The next step would be to hook up a fuel pressure gauge between the pump and carb, and run the boat. Fuel pressure needs to be 3 to 7 psi at all times. This test is going to be pass or fail, you will either have fuel pressure or you will not.

If fuel pressure is low - The very next step is to get a portable tank and hook that up to the fuel pump and see if pressure comes back up or not. If it does, there is a problem with the boats fuel tank. You will want to check the tank for signs of trash, inspect the fuel lines to see if they are collapsing, and then see if the tank has an antisiphone valve on it (and if it does, replace it)

If fuel pressure is still low on the portable tank - The fuel pump is weak.

If fuel pressure is good, then the problem is going to be inside of the carb. I know you said you rebuilt it, but if you do the above testing and get this far with no result, the problem is still going to be inside of the carb. It's either still dirty, or the float is hanging up a little bit. Does that all make sense to you?

Expert:  Jason replied 11 months ago.

I don't know how you want to leave this but that is where you stand on your end and what needs to be checked. I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case 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. The ratings box is located at the top of the screen, you might have to scroll up if you do not see it. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you


Customer: replied 11 months ago.
Timing is advancing 1V thunderbolt ignition. Distributer is rebuilt and new fuel pump. Inspected fuel tank and it was clean with no water in it!
After running boat for15 minutes it runs like new for more than 5 hours. I have done this four different times.
Expert:  Jason replied 11 months ago.

Did you check the actual fuel pressure itself?

Customer: replied 11 months ago.
Will check monday August 15
Expert:  Jason replied 11 months ago.

Sounds good, let me know how you make out.

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