2002 Mercury Outboard 4 stroke

[antiquemarge]

We have a 2002 4 stroke mercury outboard motor which starts fine and idles fine, goes to 2000 rpms and won't accelerate past 2000 under load. Any suggestions as to what the problem would be. Thanks Antiquemarge

 

[achris]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

In the thread title you say 2 stroke, in the text you say 4 stroke. And you don't give us the engine size (hp).

My crystal ball is good, but not that good.... Need a little more information to make a reliable suggestion....

 

[Dave1027]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

Chris, just split the difference and call it a 3 stroke.

 

[achris]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

Chris, just split the difference and call it a 3 stroke.

A few years back (1883) someone (Samuel Griffin) built a 6 stroke engine. The extra 2 stokes were 'cleaning' strokes. Before the next fuel charge was drawn in the piston would pull fresh air in and clear out all the exhaust.... It never really caught on....

Chris......

 

[antiquemarge]

Re: 2002 Mercury Outboard 4 stroke

Thanks for answering my question and I'm sorry for not including everything you need. I'm not only new at this site, I know nothing about boats, I am doing this for my husband. He bought the boat used in April of this year and has not been able to use it at all. It is a 2002, 9.9 HP, 4 stroke. So far my husband has put in a new computer, new ignition coil, and new ignition charge coil. checked the timing, completed a compression check, carburetor has been thoroughly cleaned, fuel lines have been flushed and cleaned, and the fuel tank cleaned, has a new fuel filter. Thanks again.

 

[antiquemarge]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

How do I change the 2 stroke to 4 stroke in my title, Thanks, Antiquemarge

 

[achris]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

How do I change the 2 stroke to 4 stroke in my title, Thanks, Antiquemarge

Hi,

In your first post click on the

button and change the title from there.

As for the 2002 9.9hp 4 stroke....
Check that the timing is advancing to the correct setting. Check that the propeller isn't too big for the load it's being asked to push... More information on the prop size and the boat the engine is on would also be helpful...

If you don't already have it, download the service manual HERE. The password for the file is <ribforum>.

Chris.........

 

[makindue]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

Also in my 2002 4 stroke mercury outboard motor, I want to check the possible problems for it before it get worst.

 

[antiquemarge]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

The motor is a 2002 EL 9.9 4ST Serial Number: OT496017 The motor will not rev over 2200 RPMs under load with prop turning, the boat has a bypass to just rev the motor with out turning the prop...In a test tub with the throttle bypass activated the motor will turm up to 3000 rpms but no more.


Here is what I have done so far:

1) Replaced oil pressure switch.
2) Replaced Ignition Charge Coil
3) Checked Carb
4) Checked all timing alignment marks on Belt, Flywheel, and Crank
5) Checked timing with light it advances properly
6) Replaced Ignition Coil, Plugs etc.
7) Compression and Leak Down test where OK.

All resistance reading where OK per manual.

I have a trigger coil on order and a fuel pump ordered...

Had it to 2 mercury dealers and they determined the prop size is OK. but could not figure out what was wrong.

If any more info is needed please ask me, I will offer as much as I can


Thanks in advance

 

[jmj120]

Re: 2002 Mercury Outboard 4 stroke

Not to be a smart *ss, but if 2 Merc mechanics can't fix it, I think I'd get a 3rd opinion. Something doesn't add up.

 

[Dave1027]

Re: 2002 Mercury Outboard 2 stroke

Re: 2002 Mercury Outboard 2 stroke

Had it to 2 mercury dealers and they determined the prop size is OK. but could not figure out what was wrong.

If I were you I'd inform Mercury they have two incompetent dealerships.

 

[achris]

Re: 2002 Mercury Outboard 4 stroke

If I were you I'd inform Mercury they have two incompetent dealerships.

I wouldn't be so hasty. I have seen some very nasty problems stump some very experience and talented people.

I had a very similar problem about 15 years ago on a 4 stroke 25hp. I used the correct troubleshooting technique in that when I put a new part in, if that didn't solve the problem I took it out and put the original part back in. That engine had 2 faulty parts, and ECU and a coil. Following the right practises didn't fix it. We had to just put all new parts on it, then start putting old parts back on until it failed. Basically checking all the original parts against known good news. The difference was that we got the the engine going right, then found our faulty parts....

Only revving to 3000 out of gear is a good indicator that something is seriously wrong... It should rev to destruction....

Have you checked the valve timing?

Chris...........

 

[achris]

Re: 2002 Mercury Outboard 4 stroke

If the valve timing is ok, then I would be starting to look for something esoteric. Like worn cam lobes, weak valve springs, blocked exhaust. How about a broken woodruff key on the timing gear on the camshaft or crankshaft?

Chris.......

 

[antiquemarge]

Re: 2002 Mercury Outboard 4 stroke

I need a carburetor diagram of a 9.9HP 323 Mercury outboard engine. Thanks in advance. antiquemarge

 

[achris]

Re: 2002 Mercury Outboard 4 stroke

Have you downloaded a service manual? If not, click HERE, the file password is <ribforum>. Lots of all sorts of diagrams in there....

Chris.........

 

[antiquemarge]

Re: 2002 Mercury Outboard 4 stroke

The diagram of the carb in the manual I downloaded is for a lower cc engine, I need a carburetor diagram of a 9.9 323 cc. Thanks in advance

 

[achris]

Re: 2002 Mercury Outboard 4 stroke

That's the manual in my last post, 323cc... The one you downloaded was for the 232cc....

Chris..........

 

[antiquemarge]

Re: 2002 Mercury Outboard 4 stroke

OK, I'm really confused now. Did I download the wrong manual or am I not going to the correct page in this manual. My husband, who is very knowledgeable, about carbs and motors, says the carb in the manual I downloaded is the 232. I'm sorry for being such a bother, but I'm sort of the go between for information on this boat. Marge

 

[achris]

Re: 2002 Mercury Outboard 4 stroke

There are two different 9.9hp engines. One is 232cc and the other is 323cc. The first manual you downloaded was for the 232cc engine, not the one he wants (delete it). Click HERE for the right one.... Same password.

Chris.........