3.0 sputtering at 3000 rpm. i need help FAST.

[snowman51789]

i have a 3.0lx mercruiser with a alpha 1 outdrive. the problem is when i get out on the water and go to take off the motor runs perfectly normal untill it hits 3000 rpm. then it starts sputtering and dosent want to go any faster. i opened the engine hatch, took the flame arester off, had my girlfriend give it gas to get up on a plane when it hit 3000 rpm and started sputtering i played with the choke butterfly valve and eventauly i was able to get it past 3000rpm. after that the boat runs fine. but then the next time i took it out it did it again.

any advice would help out alot.

thanks

 

[NHGuy]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

What year & version 3.0LX Alpha One? So once you choked it past 3k it went on up to how many RPM? And could you change engine speeds above 3000 rpm? By any chance was this boat not able to plane til you got it past 3000?

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

Its a 92 and a gen 2 outdrive. It was barely on a plan at 3000 rpm. Once I got it above 3000 rpm it was a little touchy for about. A minute or 2 but after that it ran perfectly normal all day. Even when I stopped and took off again it didn't do it.

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

And yes I could change engine speeds. Im thinking about getting a carb rebuild kit on my way home. But im just winging it. I've have to have it fixed by tomarrow

 

[Reming870]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

Water, fuel filters? Maybe change the seperator and filters first, its cheaper than just jumping into a carb rebuild. When was it tuned?

I had a similar problem last year at 2500 RPM and found water in the seperator. Just enough fuel flow flow at 2500 RPM to force water in.

 

[45Auto]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

When's the last time it had a complete tune-up? Plugs, cap, rotor, points if it has them? More carbs are sacrificed to electrical problems than you can imagine ....

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

i dont think i have a fuel/water seperator. or if i do i cant find it.

i put new plugs and wires in at the begining of the year and checked the timing. all was good. and its a digital ignition.

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

Although I do have an incline fuel filter (yes I mean the kind you not supposed to have). Could there be water in there that could be causing this?

 

[Bondo]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

and started sputtering i played with the choke butterfly valve and eventauly i was able to get it past 3000rpm.
Although I do have an incline fuel filter (yes I mean the kind you not supposed to have). Could there be water in there that could be causing this?

Ayuh,... It's obviously a Lack of fuel issue,...
Ya gotta figure out Why...

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

ya thats what im trying to ask and find out

 

[Reming870]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

I think you meant In-Line filter. An In-line will not hold water but could reduce flow rate to create the problem. If you get past 3000 RPM can you maintain a higher RPM for a long period? If you back down from a higher RPM does the problem occur again at 3000?

Does the problem occur in Neutral and 3000 RPM?

Is the tank check valve OK?

Do you run any fuel additives for the ethanol abuse?

I wouldn't jump to the carb until you can rule out all other fuel and electrical issues.

 

[dirtdog38]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

how does it sit ther in run when it wont go over 3 grand. when u played with it running did you close the chock if so that can be a carb fix alot of times when thers somthing in ther. the carb. same with a idal run it up out of gear to a high rpm and dang dear chock it off do it a few times will fix a carb if not take it apart and clean check the float most of the time no parts are needed if thats what u did on the water that day u chocked a little of it out of ther do it a few times might all me gone

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

i rebuilt the carb and that did not do anything. there for im sure its not the carb.

once it is past 3000 RPM yes i can hold higher rpms

when its in neutral yes it will rev past 3000 rpm with no problem

no fuel additives untill today i put dry gas in it (did not affect anything)

if i am at a higher rpm and back down below 3000 yes it will do it again. it just started doin that today. the last 2 times once i got it past 3000 for a minute or 2 i was home free for the rest of the day.

today i took it out, the problem didnt go away so i stopped, turned the motor off and started look around for any possable loose wire etc. whe i started it back up to head in it ran for about 3 seconds and shut off and would not start back up. it would not even sputter or attempt to start, just crank, crank, crank, crank. but when i got it home i took a plug out to check for spark and i had spark. so i put it back togather and tried to start it up and it fired up. so as of now im thinking the cap and rotor are bad. im off to west marine tomarrow at 9 am unless anybody else has any ideas.

 

[elkhunter338]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

Just my thought it is the electronic ignition at different temps and rpms it starts malfunctioning.
A rotor cap will probably not leave you dead engine it will cross fire and run horrible.
If it was fuel related you should not beable to run above 3k if 3k is your problem. you could always plumb in a fuel pressure gauge at the carb to make sure you have good fuel pressure.
If you do not have a fuel/water separater you should get one.
Dry gas in the yellow bottle I believe mixes with water but does not mix with gas, the stuff in the red bottle is better.

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

I am still having this problem any other ideas. Now it only seems to seems to do it for about the first 15 mins when you start it up and go. Then it goas away and everything is fine

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

Bump. Anybody?

 

[Raystownboater]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

I ran into almost the same scenario and my issue turned out to be a coil. Would run like a champ in the driveway, slow speeds in the water but when I hit about 3500rpms, it would spit and sputter and eventually die, if I didnt throttle back. I am also the victim of replacing perfectly good carbs to fix an electrical issue.

 

[Bonanzadave]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

I would consider a portable gas tank with fresh gas. Try it. Cheap easy way to eliminate any possible contaminated fuel issue. I did what youre doing 5 years ago. It was bad gas.

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

York boater. Would your boat eventualy go over 3500 after say about 15 mins? Cuz mine dose then its normal untill I let it sit for an hour or so. I tried fresh gas already. I use the boat alot. I fill it up atleast once s week

 

[snowman51789]

Re: 3.0 sputtering at 3000 rpm. i need help FAST.

bump. any other idea?