Mercruiser 3.0L stalls at ~2000RPM when cold

[izaver]

Hello All,
Great forum and great community! Indispensable resource for a new boater like myself. Thank you!
I have a Mercruiser 3.0 IO Alpha I and it starts up and idles fine at the dock. Though when I try to accelerate, it stalls. I have to either restart the engine or to pull back on throttle to keep it going. After about 3 or 4 attempts, the boat planes and everything works fine. After that, when it's warmed up, I don't have that problem at all -- can turn off the motor, let it sit for an hour, turn back on and everything works fine. Just when it's cold... RPM @ WOT is at 4500. Oil is clean. New prop.
The boat was not used this season, I just bought it few weeks ago.
So far, I seafoamed the carb, put fresh gas in it and that's pretty much it. I am planning to replace fuel filters this weekend.
What can be attributing to this stalling issue? Do I need to have carb rebuilt? Fuel Pump? Anti-siphon valve?
Appreciate your help.

 

[chiefalen]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Do you know how to start and run a carbed motor.

If it runs good when it's warmed up, why don't you run it say 5 minutes at the dock and let it warm up?

First pump the throttle 2-3 times, then in neutral leave the throttle 1/3 of the way down or the first click on the throttle.

Start the motor might have to give it a little more gas if it wants to cut off.

Let it run till it is warm.

Than go.

When you run it and stop, let it idle for 2-3 minutes, then shut her down.

Try my suggestions on the water and let us know how you made out.

 

[ne7800]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

probably wouldn't hurt to do tune up plugs, wires, cap, rotor, points, set the timming

 

[Don S]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

I have a Mercruiser 3.0 IO Alpha I and it starts up and idles fine at the dock. Though when I try to accelerate, it stalls. I have to either restart the engine or to pull back on throttle to keep it going. After about 3 or 4 attempts, the boat planes and everything works fine. After that, when it's warmed up, I don't have that problem at all --

Sounds to me like you are expecting it to act like your car that has EFI. You have a 4 cyl engine with a carburator and a choke. Until it warms up it will be a PITA to operate.

 

[chiefalen]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Here is a old post, hope it helps.

Alot of young people never had to start a carbed automobile.

http://forums.iboats.com/showthread.php?t=279911

Good luck. Enjoy.

 

[imported_TheMan]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Make sure your choke is properly set. You can read how it should be set in the manuals. I would guess your choke is not configured properly... maybe over choking it and causing it to stall when youre giving it gas. See Don's link for the manuals below:
http://forums.iboats.com/showthread.php?t=251571
#26 for you I believe...

 

[izaver]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Thank you all for your replies.

Here is a old post, hope it helps.

Alot of young people never had to start a carbed automobile.

http://forums.iboats.com/showthread.php?t=279911

Good luck. Enjoy.

That's the way I do it (not because I knew it, but because I read your start-up instructions right after I got the boat).
As far as warm-up. I let it idle at the dock for a few minutes while loading the boat. Maybe... 2-5 minutes. Also, the time on low throttle to get out of "no wake" zone. And than it starts acting....
I checked the sparkplugs -- they look good, but I'll replace'em anyway along w/fuel filters.

Make sure your choke is properly set. You can read how it should be set in the manuals. I would guess your choke is not configured properly... maybe over choking it and causing it to stall when you're giving it gas. See Don's link for the manuals below:
http://forums.iboats.com/showthread.php?t=251571
#26 for you I believe...

Will check that. Thanks for the tip and the link.

I am not sure if I'd be able to test it on the water this season, but I'd like to do whatever I can to get it ready for the next year.
Your help is greatly appreciated.

 

[chiefalen]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Electric choke i hate them.

I got old style.

Follow the procedure on how to adjust it.

Might be one click right or left. Maybe 2 clicks.

 

[chrisg]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Just want to add my 2 cents, I also have a 3.0L merc I/O and it has the same issue all the time. I just start off slow, then once is good and warm. I can start pulling skiiers. You learn to live with it. (letting it warm up helps)

 

[ron7000]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Hello All,

a) it starts up and idles fine at the dock.

b)Though when I try to accelerate, it stalls.

c)After about 3 or 4 attempts, the boat planes and everything works fine. After that, when it's warmed up, I don't have that problem at all

[d)RPM @ WOT is at 4500.

e)I seafoamed the carb

f)What can be attributing to this stalling issue? Do I need to have carb rebuilt?

g)Appreciate your help.

a) choke is working, and choke opens up fully by the time you go to give it throttle.

b) because it's leaning out

c) because once it's warmed up, it can tolerate the leaner mixture but it's just rich enough to get by on. Some might consider it the optimal mixture for economy and emissions except for the side effect of leaning out on acceleration.

d) nothing "wrong" with carb, nor choke, nor fuel pump, nor anti-siphon valve, or any of that other crap.

e) how do you seafoam the carb? the only thing that really works is opening the carb up and using carb/brake cleaner or compressed air. Additives in the gas are a waste of money.

f) you don't need to have the carb "rebuilt". the problem is the mixture and can be fixed by either or both of the following: raising the fuel level in the carb bowl by adjusting the float, and/or increasing the size of the main jets from 1.55mm to 1.65 or 1.7mm. It's a simple carb tuning issue. The original setup is on the leaner side in an attempt for an optimal a/f ratio for economy and emissions, the consequence is if any dirt or contamination is in the carb and blocks fuel flow the slightest bit the engine will run lean at certain rpms- between 1500-3000 rpms when the carb is in the "transition" circuit. This is the carb circuit that is most easily contaminated and causes all the bog on accelerations issues that everyone has with the 3.0L, but once you get out of that throttle range the main circuit (main jets) and power valve flow fuel and the engine runs fine.

g) your welcome,

remember the words

transition circuit

and

lean out

and you can be a carb guru and post on iboats.

 

[izaver]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Ron, thanks for detailed write-up.

e) how do you seafoam the carb? the only thing that really works is opening the carb up and using carb/brake cleaner or compressed air. Additives in the gas are a waste of money.

I sprayed Deep Creep into the carb while at high idle trying to stall the motor. Turned the motor off, let it sit for 10 min, restarted and ran the boat at WOT.

f) the problem is the mixture and can be fixed by either or both of the following: raising the fuel level in the carb bowl by adjusting the float, and/or increasing the size of the main jets from 1.55mm to 1.65 or 1.7mm.

Ok. Time to read the manual on "adjusting the float"...

Thanks again for all your replies.

 

[chiefalen]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Who said youth is wasted on the young?

All you need to do is warm it up.

My friend has the setup same s--t.

Repeat after me i will let it warm up at the dock for 5 full minutes.

No more snake oil in the carb.

No fiddling and breaking a 245 dollar carb.

No fiddlin with the carb screw, btw don't over tighten it going in and bending the tip then your really got the ole royalhowanagotcha.

Nada.

 

[ron7000]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

a) All you need to do is warm it up.

b) My friend has the setup same s--t.

c) Repeat after me i will let it warm up at the dock for 5 full minutes.

d) No fiddling and breaking a 245 dollar carb.

a) but he does, and chrisg has the problem all the time.

b) ok, and I has the setup same s--t. i also had this same problem, all the time, and fixed it by what i said.

c) umm yeah, that guaranteed extra 3 minutes ought to do the trick.

d) Repeat after me: when i want to chime in on something technical I will have a clue, and i will not toss out subjective statements and characterize something such as tuning a carburetor with fiddling and breaking a $245 carb.

 

[chiefalen]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

Just what rock did this little dog excretment crawl out from under.

I used to have a dog named ron i shot him.

Ron whenever you need a job call you can clean the toilets at work.

Carb choke needs to open all the way.

With electric chokes it takes about 5 minutes.

If you read his post once it warms up it runs fine.

Starts fine on the water so forth.

 

[chrisg]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

a) but he does, and chrisg has the problem all the time.

b) ok, and I has the setup same s--t. i also had this same problem, all the time, and fixed it by what i said.

c) umm yeah, that guaranteed extra 3 minutes ought to do the trick.

d) Repeat after me: when i want to chime in on something technical I will have a clue, and i will not toss out subjective statements and characterize something such as tuning a carburetor with fiddling and breaking a $245 carb.

Just to let you in on my experiance, I took mine to the local marina to see about 'adjusting the carb' Worked like cra loss of power, hard starting, I ended up having to take it back to the place I bought it and they re-set everything! They told me the same thing. let it warm up before taking off. let it cool down befor turning off. I was out 160.00 ( and a week out of the water - dont forget gas for hauling it 60 miles) to learn that.

And where did the dog comments come from? I missed somthing?!?!

 

[chiefalen]

Re: Mercruiser 3.0L stalls at ~2000RPM when cold

You piggy backed your problem onto another thread.

I didn't direct anything towards you.

But you would know that by reading the thread.

But in the end you spent 160.00, that you could still have in your wallet.