225 optimax idles rough/trouble accelerating

[MatC]

Hello all!
First post ive done a lot of searching, but figured it was time to start a new thread. Serial number tag is missing from swivel bracket.

Found welch plug
Serial # 0G752223

I just purchased a 98 champion 203 with a 225 optimax. Was told motor was low on power when i purchased it. I finally had a chance to take it out and motor sounds like it is missing when underload and at idle. Had to try multiple times to get up on pad.

Here is what ive done pulled plugs and comp checked but this was before i read the proper way to do it. It was performed cold throttle closed and pressures ranged from 90 -80 psi.
Monitored air and fuel pressure had the correct 80/90 split at idle.
Checked spark with a timing light on each cylinder all plugs look the same and are the correct ngk number.
Disconnected DI injectors one at a time number 6 injector made no difference all other injectors disconnected engine would stall.

Fuel line/ bulb was recently replaced from the look of it but found a couple suspicious things.
Main 5/16 line coming into pulse pump is ziptied and outgoing line ziptied as well. Possibly sucking air?

Looking for ideas before i take it to a local shop.
Ive worked on medium duty diesels for past 12 yrs so i can turn wrenches but i am unfamiliar with marine motors.

Thankyou for any help you can provide.

[JOE54]

swap some injectors around to diff holes see in miss follows injector, Mat yo mtr is a 3.0L please check out the next section down for info on it should be ser number on welch plug on block, WELCOME well try to help ya, ps; you got a bore scope to look at sleeve for rotation

[SilverFox579]

If those are radius head zip ties all is good. In addition to Joe's suggestion there are two other possibles for serial number, it may be on a label attached to PCM and it should be a label on swivel bracket.

How to find your serial number on your Mercury outboard

[EuropeanAM]

Welcome to BBC!

I'll move your post to the correct (3L) Forum. If you would, please take a moment to read through the Announcements at the top of that forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

Go back through the BASICS:

-PROPER compression testing

-Spark Test (including verifying the correct, and good NGK IRIDIUM Spark Plugs)

-Fuel Quality, Delivery, and Air/Fuel Pressure Tests

-REED inspection (Note: A broken or missing reed can cause a cylinder to produce NO power at idle, even with good spark and fuel).

[MatC]

Thankyou for the response!
Inspected reeds with mirror and light found the very bottom reed cage with what looks to be a bent or partially missing pedal.
Borrowing a bore scope and will get a better look and also check for piston damage thru spark plug holes. My pcm did have a tag on it i will post a picture this afternoon hopefully it has serial# . Looked for welch plug and didnt see one this morning..

[JOE54]

DING DING we have a winner bottom is #6 ,damage may be hard to to see thru plug hole MAT, may be lucky jave seen several 3.0 that piece went right out exh port never touch a thing , may need to pull head though / leak down to tell for sure/pull front end off get a set of good reeds put um in it, hope all is good

[EuropeanAM]

If these are steel reeds (which they very well may be), I'd suggest replacing them with TDR Reeds. MUCH safer for the engine, and perform quite well as they were designed specifically for this engine.

[MatC]

If these are steel reeds (which they very well may be), I'd suggest replacing them with TDR Reeds. MUCH safer for the engine, and perform quite well as they were designed specifically for this engine.

Can you pm me with purchase info on these i would like a set and any gaskets needed to install them properly!

[MatC]

DING DING we have a winner bottom is #6 ,damage may be hard to to see thru plug hole MAT, may be lucky jave seen several 3.0 that piece went right out exh port never touch a thing , may need to pull head though / leak down to tell for sure/pull front end off get a set of good reeds put um in it, hope all is good

I hope im get lucky would make this boat a really good deal!
Definately lost an entire pedal after scoping it.
Looked at the piston and it looks fine but could only see about a third of it because of sparkplug angle. I can still see honing marks in the sleeve.

[MatC]

Also do either of these pictures show my serial # ?

[JOE54]

Also do either of these pictures show my serial # ?

no,/yes but you need to look all the way around sleeve, with intake off you can see back side some also, may have gotten lucky

[SilverFox579]

Serial number would be formatted digit, letter, 6 digits, example, 1B234567. Did you also check swivel bracket for the label (link provided above shows examples)?

Here's contact info for parts orders, Rhonda does an outstanding job - If you want to order or price Mercury Engine Parts or Accessories

[MatC]

Serial number would be formatted digit, letter, 6 digits, example, 1B234567. Did you also check swivel bracket for the label (link provided above shows examples)?

Here's contact info for parts orders, Rhonda does an outstanding job - If you want to order or price Mercury Engine Parts or Accessories

Found the welch plug! Updated first post with serial number..

[EuropeanAM]

Good deal!

Serial# 0G752223
Model# 1225473UD
MERCURY 225DFI L 3.0L Optimax
DOB: 4/28/98

[MatC]

Update, found a couple hrs to take apart intake.
Found broken reed pedal stuck to the reedblock a couple pedals over! There are half a dozen pedals that are cracked/ missing small pieces. Just waiting on parts and will get it going back toghether/ test run..

[SilverFox579]

Count your lucky stars that petal didn't go through the intake!

[greauxpete]

Good job! Glad you caught it..

[MatC]

Have an update. Got the reeds installed and primed the oil system. Took boat to the lake and it runs a better but still isnt correct.

The boat still is really slow to get on pad and still runs a little rough at idle.

I couple times i got a check engine light and a single beep about 20 seconds after returning to idle from a run.

Also boat will only turn 4200 rpm

Any suggestions before i take it to a local shop?!

[greauxpete]

Did you ever get the compression using the correct procedure?

(Engine warmed up, all plugs pulled, fully charged known good battery, throttle at WOT position, calibrated compression gauge)

If your compression is out of spec, this may be why your not achieving max rpm. This may keep you from spending time and money unnecessarily..

[MatC]

Did you ever get the compression using the correct procedure?

(Engine warmed up, all plugs pulled, fully charged known good battery, throttle at WOT position, calibrated compression gauge)

If your compression is out of spec, this may be why your not achieving max rpm. This may keep you from spending time and money unnecessarily..

I will find time this week to do a compression test.

Think i will replace sparkplugs while there out!