Fuel delivery issue

[wahlejim]

I am pretty sure I know what is going on here, but just want to verify I am not overlooking anything.

Mercruiser Engine, 1983 228hp, 305 gm, serial number 6271653

Boat is in the water for the season. First time out, just on plane, at 3200-3500 rpm, starts stutterin and poppin. Detonation and low fuel delivery is my diagnosis at this point. Brand new canister style fuel filter, poured contents of old and small amount of crud came out.

Kept boat in water and reved out of gear to 4400 no problem. Under load, not getting the fuel it needs. Remote fuel tank yielded the same issue.

I am going to be pulling carb for a rebuild. Is there anything I am overlooking?

 

[Bt Doctur]

Stop reving it up in neutral , Might examine the inside of the dist cap, check the plugs , and plug wires. Run it at night with no lights to see if cap or wires are arcing.

 

[alldodge]

Anti-siphon valve can get hung up from the crud

 

[harleyman1975]

was going to second the ignition side as well. possible weak fuel pump?

 

[wahlejim]

AllDodge I used a remote fuel tank to rule out issues with venting and the anti-siphon.

DC, wires and rotor were replaced 2 years ago, about 45 hours on engine since replacement. Spark plugs new last year, only 20 hours on them, but I will pull it all and check for arcing as well. Sure beats a carb rebuild.

 

[wahlejim]

I have a new DC, rotor, plugs, and wires on their way. I am having a heck of a time locating a carb rebuild kit.

Rochester Quadrajet
Carb number is 1708O565 0822
Engine Serial Number: 6271653 which I have discovered puts it at 1985, not 1983 as previously mentioned
Mercruiser MCM228 GM305

Any help is appreciated

 

[alldodge]

That carb appears to be a Merc unique build by Rochester. Your engine serial number puts you in this area
http://www.mercruiserparts.com/230-4-bbl-gm-305-v-8-1985-1986-6218

It list 3 carbs, one Merc and Rochester 2bbl, and one Merc 4bbl.
http://www.mercruiserparts.com/bam/subassembly/31727/1077/100

Searching for 17080565 does comes up empty and here is the listing
http://www.carbkitsource.com/carbs/numbers/Rochester/Quadrajet/17080201-17082526.html

The Merc kit number is 823426A1 and if you search on it there are several kits available. So if your carb looks like the one in the second link I would suggest using the Merc number to search for the kit

 

[wahlejim]

Thank you AllDodge! That helps a ton!!!!

 

[andrewterri]

I learned the hard way not to rev out of gear. I jumped the timing chain on a 302 doing this and it put a valve into the piston as these are interference engines. Thought i would throw that out there to save you the same fate i had.

 

[wahlejim]

Just out of curiosity, would a bad alternator cause any of these symptoms? I fired it up after a spark plug change, wire change, and dc change and noticed what sounded like a bad bearing in the alternator. Wasn't able to test voltage as I didnt have my meter on me. Will test it this weekend, just wondering if that could be the cause of this.

 

[alldodge]

An alternator bearing can put a load on the motor and if it seizes it will burn up a V-belt. To find out if its the ALT remove the belt and spin by hand feeling for roughness. If its smooth, start the motor without the belt and listen if the noise is still there

 

[wahlejim]

Issue Resolved....

New DC, Rotor, wires, and plugs

Same issue

Started pulled the fuel line from the carb. Looked at the filter and the outside looked clean. Brother in law says "See, its clean." I slapped my forehead. "you do realize that fuel goes through the inside of this, right?" Blank stare on his face.

Pulled the filter, inside was caked in this off white grit, not quite sand, almost like ethanol deposits. They either got through the canister filter somehow or formed inside over the winter. Anyone have an explanation for this?

Anyway, cleaned the carb filter, re-assembled, engine runs like a top!

I have the re-build kit so I have a winter project to keep me busy for awhile while the snow flies. But for now, with how well it is running, I am not touching it and losing more of this boating season.

Lessons Learned:

Always verify other people's work when they are working for free beer.

Check the simple thigns first before creating a bigger project for yourself

 

[Bondo]

Pulled the filter, inside was caked in this off white grit, not quite sand, almost like ethanol deposits. They either got through the canister filter somehow or formed inside over the winter. Anyone have an explanation for this?

Ayuh,.... What's to explain,... It's "Stuff", other than clean fresh gasoline,....

 

[wahlejim]

I was just curious if it got through the filter or formed after the filter during its winter hibernation

 

[alldodge]

Great to hear

 

[andrewterri]

glad it was something simple