Rebuild/Clean Carb - Or Not?

[4winnsskipper]

Gentlemen and Ladies,

I got a Volvo Penta 3.0 GS PCNA , 1.97 SX Drive, in my 170 Horizon 1996 model four winns. Engine is original from 96, but only has 101 hours on it...Engine doesn't start as well as i would hope it would, lots of choking ,throttle pumping, etc, but sometimes will start quicker than others....starts right up when warm though... and doesn't like to idle until it starts warming up. However once engine is warm, she idles, shifts, drives, restarts just fine

I have noticed some hesitation on her in the mid rpms when going from idle to WOT, but overall runs great. I've burned through tanks of gas already, and used the recomended 2+4 evinrude fuel conditioner per the manual i've memorized, so i do not beleive fuel quality, nor spark quality to be an issue... I do notice the boat will only do 35-40mph at the recomended top RPM range of ~5,400 RPMS.... the local four winns dealer thinks its too slow for the boat, and i would agree...the boat receives new plugs, cap, rotor every season, and is treated what i would call very well by me, i don't hold it at WOT much at all, rather well below max rpm when running across the lake... i swapped pitch props, and blade counts, and am currently running a 3 blade 21 pitch which puts me right where i should be for rpm at WOT.

so i bought a carb rebuild kit for it direct from volvo penta hoping i could figure it out...well i read the directions and long of the short, i'd rather have a pro rebuild/clean her up...

question is

1) should i fix something that ain't broke?
2) any other signs of a carb in need of cleaning/rebuild?

Engine sat most of its life so that's what worries me....boat and engine look NEW, boat VERY well cared for during its life, Hull is flawless, interior flawless, paint on engine still black, only a few spots of rust on the block from draining the block/manifold in winters...

Thanks in advance for your thoughts/consideration/and time!!

 

[Don S]

Re: Rebuild/Clean Carb - Or Not?

Could be the carb, when was the last FULL tuneup and compression check.

 

[Gary H NC]

Re: Rebuild/Clean Carb - Or Not?

If you have never rebuilt a carb then you are in for a treat,,

The hesitation could be the accelerator pump is worn inside the carb.
It is a rubber plunger that pushes fuel on hard acceleration.
Sounds like the choke is most of your problem for hard starts when cold.

I would say let a shop put the rebuild kit in or at least read up on the procedure..

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

I figure removing the carb is only a matter of loosening a couple connections and four bolts and it wont hurt to have the carb gone through

also i meant 4,200 RPMS not 5,400!!! whoops im surprised Don didn't give me a hard time on that one!!


Thanks guys!!

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

Could be the carb, when was the last FULL tuneup and compression check.

Don compression came back even on the boat last year, all within 10psi of each other, i forgot the actual numbers

and you say FULL tuneup, each person has their own opinion but the boat receives the winterization and summerization per the manual AND your write ups. All plugs/cap/rotor changed each year, Evinrude fuel condition used twice a year (winter storage and mid season), i run 89 octane per manual and not sure what else i could be forgetting but i treat her right. Again boat is dead reliable (knock on wood), runs great once warmed up, its the first few minutes of cold startup that bothers me and lack of total top end...

 

[Don S]

Re: Rebuild/Clean Carb - Or Not?

its the first few minutes of cold startup that bothers me and lack of total top end...

That, my friend, is perfectly normal for any CARBED engine. Nature of the beast.

 

[Glassport from Newport]

Re: Rebuild/Clean Carb - Or Not?

Be carefull taking the carb to a shop for rebuild. Sometimes it's cheaper to buy a new one after parts and labor.

I had problems with my Mercruiser 3.0. It had the junk Mercarb on it. I rebuilt it and still had problems. I then sent it to a shop. They rebuilt it and it still had the same problems. I then bought a Rochester carb with a Mercarb adaptor plate off of ebay for $250, and my problems were solved. Boat ran great and had no tuning problems. I could have save $200 had I just bought that new carb in the first place ($50 for each rebuild kit & $100 for labor).

Later, I tore apart the Mercarb to try to find the problem and found out that the seat for the idle mixture screw, was severely deformed (someone turned the screw too tight).

 

[Don S]

Re: Rebuild/Clean Carb - Or Not?

Later, I tore apart the Mercarb to try to find the problem and found out that the seat for the idle mixture screw, was severely deformed (someone turned the screw too tight).

I have found that on many carbs both Mercarbs and Rochester. The biggest cause of the problem is water in the fuel and passages in the carb, then a lot of setting around and corroding.

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

Be carefull taking the carb to a shop for rebuild. Sometimes it's cheaper to buy a new one after parts and labor.

I had problems with my Mercruiser 3.0. It had the junk Mercarb on it. I rebuilt it and still had problems. I then sent it to a shop. They rebuilt it and it still had the same problems. I then bought a Rochester carb with a Mercarb adaptor plate off of ebay for $250, and my problems were solved. Boat ran great and had no tuning problems. I could have save $200 had I just bought that new carb in the first place ($50 for each rebuild kit & $100 for labor).

Later, I tore apart the Mercarb to try to find the problem and found out that the seat for the idle mixture screw, was severely deformed (someone turned the screw too tight).

volvopentastore.com wants 650 bucks for a new carb

where else would i look for options?

also one quick question, i also noticed yesterday during "summerization" that the engine wants Zero degrees of timing (i've never played with timing on this motor, no changes to it)... that seems awefully low....especially when im suppose to run midgrade (89 octane) per manual. Why does it want such low timing? Heck my supercharged mustang runs 20 degrees total timing, 10 initial BTDC.... and that runs warmer, 180-190 degrees!!! not to mention inlet temps of 200 degrees at 10psi!! im sure there is a reason for it, just wondering why...seems that leaves alot of power on the table thats alll...

 

[a70eliminator]

Re: Rebuild/Clean Carb - Or Not?

volvopentastore.com wants 650 bucks for a new carb

where else would i look for options?

also one quick question, i also noticed yesterday during "summerization" that the engine wants Zero degrees of timing (i've never played with timing on this motor, no changes to it)... that seems awefully low....especially when im suppose to run midgrade (89 octane) per manual. Why does it want such low timing? Heck my supercharged mustang runs 20 degrees total timing, 10 initial BTDC.... and that runs warmer, 180-190 degrees!!! im sure there is a reason for it, just wondering why...seems that leaves alot of power on the table thats alll...

What do mean it wants 0 degrees timing? Is that whats specified for the engine? TDC just doesn't sound right.

 

[Don S]

Re: Rebuild/Clean Carb - Or Not?

also one quick question, i also noticed yesterday during "summerization" that the engine wants Zero degrees of timing (i've never played with timing on this motor, no changes to it)... that seems awefully low....especially when im suppose to run midgrade (89 octane) per manual. Why does it want such low timing?

Because it's a Delco EST distributor, it has to be put into service mode to set base timing. On that particular module, when in base timing mode you have to set it at 0? so when it comes out of base timing mode it will be at the correct point.
http://forums.iboats.com/showthread.php?t=271407

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

Don - As usual you are huge help, Thanks !!!

 

[Gary H NC]

Re: Rebuild/Clean Carb - Or Not?

I have used these guys a few times...great warranty and very good prices..
http://www.marinecarburetor.com/

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

I have used these guys a few times...great warranty and very good prices..
http://www.marinecarburetor.com/

Thank You sir!

How do i find out which one on that website is the same one as mine? If i purchased one off there, is it a direct bolt where i just fasten the carb/line and go??

Sorry im a fuel injection guy, never dealt with carbs

My engine, Volvo Penta 3.0 GS, PCNA, actual OMC CObra leftover 3.0 engine with Volvo Penta stickers/outdrive.

 

[Gary H NC]

Re: Rebuild/Clean Carb - Or Not?

The ones i have bought from them were just bolt on and go.
They flow test and set them up for your engine.
The only adjustments i have had to do on them is idle speed.
Usually the idle mixture was dead on...

Look close at your carb and see the numbers stamped on the side.
Is it a Rochester?
Plus what the choke and fuel inlet look like.
Give them a call with that info and compare with the pics on the website.
They will fix you up.

You can send them your carb and they will rebuild and send it back or exchange it for the exact replacement...just tell them what you want.

Look at this page...It may be the one but tells you where to locate the numbers,
http://www.marinecarburetor.com/Y42-2300.htm

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

Yeh that sure looks like it!! im going to look into this further - Thank You!!

I just toke her out yesterday, it was COOOOLLLDD out, 38 degrees!!!!

I ran her on muffs in the driveway during summerization if you will then went for a spin on the lake, and it needed to idle for a long time before i could shift her into gear, she kept dying... anyway when going from idle to WOT, there still is a "hesitation" when the trottle is "floored", studders for a second or two then tears wide open just fine, but even still im feeling it should still be faster, only 36mph with at 4300rpm

 

[Gary H NC]

Re: Rebuild/Clean Carb - Or Not?

Even a new carb can have that stutter on hard acceleration....just the nature of them.Its very minimal if the carb is adjusted right.

How are you reading speed? A GPS is the only accurate way.
The boat speedos can be off by well over 10 mph even on a brand new boat.

 

[4winnsskipper]

Re: Rebuild/Clean Carb - Or Not?

Even a new carb can have that stutter on hard acceleration....just the nature of them.Its very minimal if the carb is adjusted right.

How are you reading speed? A GPS is the only accurate way.
The boat speedos can be off by well over 10 mph even on a brand new boat.

paddle wheel on depth sounder and stock speedometer , bothin within 2mph of each other. never run a GPS in it yet. will try this year

but the more i think about it, the more im just happy shes dead reliable and will have to live with the nature of the beast (cold idle, slight hesitation...stupid carbs....)

 

[captmello]

Re: Rebuild/Clean Carb - Or Not?

Have you tried one of these Prop calcs?

http://continuouswave.com/cgi-bin/propcalc.pl

Give it a try.

BTW, I think you should be higher than 4200 @ WOT. Probably should be running 19".

 

[Gary H NC]

Re: Rebuild/Clean Carb - Or Not?

I think some checking and adjusting the choke may solve the cold nature of your start problems.
Is it the electric choke or heat tube?