Need to rebuild carbs on my 115, jetting question

swflhummer · Dec 25, 2010

Everytime I take the boat out, I notice it uses A TON of gas... Also when I try to get up on a plane, it doesn't go over a certain RPM for awhile and finally kicks in.

Also I'm thinking the jetting in my carbs could be wrong. After I had my engine rebuild, the carbs have gone in MANY times because they have not seemed right. And now its like this... So im not sure.

jonesg · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

How much is a "ton of gas"
how long is "for a while" ?

jerryjerry05 · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

First off check the compression/spark.check for water or junk in the fuel system.
Even though its just been rebuilt it could be having troubles.
Check the fuel pump diaphragm and valves.
What did they do on the rebuild?
If they bored all the cylinders then you might need to re jet.
Otherwise they should be OK.
Check the compression/spark and the fuel pump.Post your results.
Ethanol is messing with lots of things.
Fill out the profile you might be close to someone who can help.J

swflhummer · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

A ton of gas is enough to see it in a 5ft diameter in the water after you shut it off.
A ton of gas also means several gallons in a matter of about 30-45 Minutes.
A while, about 3-4 minutes. Almost sounds like Ignition when it starts to kick on like fouled plugs... then they clear up and go when ever it wants too. Weird (yes, ive put new plugs in a few times)

The last 4 years has all been fresh water by the way. And it may have made about 10hrs on the water in that 4 years. As of now, the tanks are completely empty.

How much is a deal to measure Compression?
Yes engine is bored over, and im not too sure how much

Also there is no tuning needles on my carb Anywhere!

I did see a post somewhere about replacing plug wires and plugs... Power pack and everything is all new.

Joe Reeves · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

What is the model number of that 115hp Evinrude?

Carburetors do not come and go. They are either fully functional or fouled.

Having a cylinder (one or more) bored oversize does not affect the carburetion, meaning they do not require re-jetting.

Awaiting that model number.

Chris1956 · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

Is it possible the fuel pump dighram is leaking raw fuel into the crankcase? This would cause fouled plugs at low speed and they would clear up at high speed, likely after stumbling while getting on plane.

wilde1j · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

You're aware that your motor will use ~ 11.5 gph @ WOT, so a "couple of gallons in 30 to 45 minutes" is nothing. If you change jets, make sure you know exactly what your doing or you will have a big, ugly paperweight on your hands.

swflhummer · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

Chris1956 said:
Is it possible the fuel pump dighram is leaking raw fuel into the crankcase? This would cause fouled plugs at low speed and they would clear up at high speed, likely after stumbling while getting on plane.

This sounds like more along the lines of whats happening. How do I go about Diagnosing this??

I love this forum btw.

If I can find my flash light ill go look for that model number if I can. the motor has been painted to it may be hard. Where is it normally stamped? I hate saying this but its actually an OMC sea drive.

And idk I just dont remember it using quite this much at my last trip in the keys for the week. We went 12 Miles out on a blown motor (didn't know this at the time because the motor was being stubborn.. Figured it was carbs) and back and used only half a tank. Can't remember what size is in it. its a 17" Dusky

swflhummer · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

Ok heres some more story that may or may not help diagnose my issue.
Out of the water it will start up perfectly. In the water it will idle fine, and after it finally gets on a plane it runs AWESOME. But it has issues getting past 1500 RPMS I think it was (it has been a good minute since I've had it out). When it Have it WOT it will drag for a bit, then you can hear the other cylinders kick on for a second and go back down. Its almost like theres a midget in there that has a toggle switch on each cylinder and is screwin with me kicking them off and on when ever it wants too that little S.O.B

jerryjerry05 · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

There are probably no adjustments on the carbs.OMC did that for a few years.
If fuel system is your problem.Check the fuel pump FIRST!!
Model and ser# are usually on the front somewhere.
You need to buy a compression tester,get the kind that screws in.
If you say it runs crappy then kicks in,I'd go for water or crap in the carbs.Bad fuel pump diaphram.
Ethanol is delaminating the inside of the older hoses.It's actually melting some hoses.
Do the simple checks.Spark,fuel pump,clean the carbs.Any inline filters?J

emdsapmgr · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

You can double check the jets in your carbs by yourself. Bombardier lists the carbs by year/engine and those factory parts lists indicate which jets the carbs came with when shipped to the dealer. Check out your engine by model/year at Bombardier's website: epc.brp.com. These jets are listed by part number on the parts diagrams. The later parts lists indicate the jets size as well as the part number. Most early parts lists just show the part number-you'd have to look them up in the cross-reference listing found in most later service manuals or call Bombardier in Waukegan, Ill. The fact that you feel the engine kicking in/out could be an indication of losing spark to a cylinder. Might be an ignition problem. If you are only running on 3 of the 4 cyls, I'd expect that it would burn a ton of gas vs distance traveled.

swflhummer · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

yeah after more and more thinking and more experience on this forum vs. working on boats since the last time I have had a chance to work on this specific boat, its def gotta be ignition. It just SUCKS because I cannot work on it out of the water because it runs perfectly fine. Its only when its in water do I know whats happening. Oh yeah, when having its little fit, pressing the choke and what not in does not make a difference which is one more reason why I do not think its the carbs.

1 more question, what fluid do I put in my trim tilt??? ATF?

swflhummer · Dec 25, 2010

Re: Need to rebuild carbs on my 115, jetting question

Could it be possible the spark is not advancing???

emdsapmgr · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

Take a friend out with you next time you go boating. When the engine acts up, pull the cowling off and put an inductive timing light on each plugwire while your buddy steers. The flashes in the gun will show you misfires, nofires and weak firing. Best to try it when the engine is in gear and under load. Idling at the dock when in gear works, too. What year is this engine? How many power packs does it have?

swflhummer · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

92 and 1 i believe

mikesea · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

Sounds to me like your low speed jets are dirty.If you have good response at full throttle then your spark is there.at idle your not putting much demand on the eng,so it may run better.but one think on the spark side that could be a problem is spark delivery ,on demand,as you try to poane,that is really the hardest time for the eng.On 4 cylinders ,sometimes the cowling can rip ,or pull a plug wir off.Ive also seen where the plug wire leaks spark thru the wire to cowl.Check all wires good and be sure they pack inside nicely.

Joe Reeves · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

It would be a big help if you listed the "Model Number" of that engine for us.

swflhummer · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

The boat is over at my shop so i have not had a chance to look at it yet.... But I ran seafoam through it today and it seems alittle better. I wont know till I get it in the water.

I was talking to dad cause about 4 years ago, he was the one dealing with it. The guy doing the work on the motor said "he was gonna make it faster" and DID put bigger jets. We assume it has 150 jetting and overloads. I am thinking this is where im at right now.

swflhummer · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

Also power pack is new, wires, are new, I put new plugs in it yesterday, complete rebuild, and every terminal I can find anywhere in and out of that motor have been sanded and cleaned.

boobie · Dec 26, 2010

Re: Need to rebuild carbs on my 115, jetting question

"Model number" might be on the lower cowling underneath the hood.

Need to rebuild carbs on my 115, jetting question

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