UPDATED and FIXED! Like It Never Ends: Carb Issues

[Ranger Danger]

Ok, 1978 Evinrude 115hp, 2 stroke 4 cylinder.

Engine started and idled good when I put fresh gas and a battery to it. But on the water it wouldn't plane out or run fast.

So after cleaning, soaking, and rebuilding both carburetors with a rebuild kit, I hook it up to the ear muffs.

Clean gas, fully charged battery, she won't start and run. She's kicking off, trying to idle, then a backfire through the exhaust. I did make sure the floats were parallel to the carb body when turned upside down, and blowing air through it as noted in the top secret file worked as it should.

I don't think I have adjustable jets, they certainly don't look like it. On my "idle" orifices I just screwed them in until they were tight, then replaced the screw plug.

Any thoughts? Is there something I need to adjust?

 

[Lion hunter]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Not sure about the high speed, but the low speed should be adjustable. Start at 1.5 turns out.

But 1st things 1st. How is your compression and spark?

Test compression
Test spark, Blue spark jumps a 7/16" gap

Backfiring can be many issues, usually to much fuel. Low comression can lead to unburned fuel and a pushing unburned fuel out the exhaust until it ignites and backfires. Poor spark can do the same as can poor carb adjustment.

 

[Ranger Danger]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Compression and spark are both good.

I think I figured it out. I'm pretty sure I mis-adjusted the floats. I made sure the carb floats were parallel when the carb was upside down, but did NOT check the clearances while the carb was upright. I'm relatively certain that the carb floats are staying open at all times, causing a flooding situation.

I'm going to pull them first thing, re-adjust, and try again.

I appreciate your response.

 

[jtexas]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

your carbs have fixed idle jets.

if you can blow air through with the carb held upside down, the float valve is open.

that o-ring under the float valve seat -- that has been forgot once or twice........

 

[Ranger Danger]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Ok, backed the idle jets out a bit, and the problem is just worse. I'm going to assume jtexas is correct, and they are not adjustable. I do actually have an idle adjust screw on the throttle linkage.

Right now it will start, but whether I have the engine revved up or at idle, it periodically backfires through the exhaust, and most of the time it dies.

The float valve is seating properly, and ALL jets are very clean, and you can easily see through them. I double checked, and the O Ring below the float valve seat is there. A new one at that.

So am I correct in thinking that my engine is getting too much fuel? And if so, is there anywhere else to look at other than the carb float assembly?

 

[Daviet]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Usually a spitting situation is from a lean mixture.

 

[Lion hunter]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

I guess we are gonna have to know the exact symptom. A true backfire (ignition of fuel) is normally out of time, or to much fuel. A sneeze however is usually a lean mixture.

 

[Ranger Danger]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Ok, it's a popping noise out of the exhaust.

I just pulled apart the carbs for the umpteenth time, and noticed something.

While pulling the top carb off, I saw that there was fuel leaking from the carb bowl of the bottom carb. Upon closer inspection, it was actually leaking out from the large opening that the butterfly's are in. There are two little brass tubes that sit side by side, underneath the butterflys.

Just to the lower left of the left tube, there is a small crack in the carb housing itself. As best as I can tell, gas is somehow leaking through this crack. I don't know if this is new or not, but when I first began messing with the carbs, I noticed a fuel leak on the lower carb, and dismissed it as a gasket leak that would be addressed with a rebuild.

I know this is not normal, and could be what is causing my problems. Let me see if I can post a pic showing the crack.

***Here is the Pic****

 

[Lion hunter]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

JB weld may be your friend. The best solution will be a replacement part. but I have done many cracked emulsion tubes and carb bodies with JB when replacement was not an option. Just be cautious with the stuff and prep it right and it does work.

Just FYI for future It has been my experience with lean and rich symptoms that rich comes out the exhaust (backfire) and lean comes back through the carbs (sneeze)

 

[Ranger Danger]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

It's funny that you mention JB Weld, because that was the very first thing that came to mind when I saw the crack.

Do you think it could be running rich from the gas coming out of the crack? If it's seeping through with just the primer bulb squeezed up, I would imagine it's doing much more when the engine is running, not to mention messing up the internal pressures and such.

I'm going to clean it with alcohol, rough the area up a bit, re-clean it then apply some JB Weld.

As bummed as I am to see that crack, it's nice to think that my problem may finally be narrowed down.

 

[Mntom]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Do you think it could be running rich from the gas coming out of the crack? If it's seeping through with just the primer bulb squeezed up, I would imagine it's doing much more when the engine is running,

If it is seeping then it would change the gas/air mixture to the rich side! I just wonder what the cause of that crack is. I did some looking and you will need to repair your old carb UNLESS you know someone who has a 'replacement' for you!! If you want to find another here is a list of other engines you can use one from: http://www.boats.net/parts/detail/brp/B-0388863.html

 

[mikesea]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

you mentioned backfire,have you checked your plug wires and the coil wires,if you have a reversal,the symptoms are as you describe,,make sure the small coil wires are right

 

[77Saturn620]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

In my personal experiences....99% of people shouldnt fool with carbs.

Got a manual?

 

[Ranger Danger]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Mntom, that's what I was afraid of. I looked online and noticed the part was "obsolete." Sigh...

Mikesea, I have checked and re-checked the plug wires, they are on correctly.

Saturn, No crap! But I'm the kind of guy who would prefer to figure something out and fix things myself. I do have a manual, and while it is very helpful, it is also very lacking in day to day experiences. For example, it tells you what can cause a backfire, but not how to fix those issues. It's a great reference tool, but it doesn't really get into details on how to fix.

 

[jimdd810]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Way to be observant ranger most people would never have even seen that little crack. I think if you fix that and redajust the carbs you should have solved your problems. Good luck

 

[Ranger Danger]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Way to be observant ranger most people would never have even seen that little crack. I think if you fix that and redajust the carbs you should have solved your problems. Good luck

Thank you sir, I'm afraid I'll need the luck!

 

[Lion hunter]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

And IMHO, the carb is the simplest component on a motor. There are only a few moving parts and the rest is just attention to detail and cleaning. I have taught my teenage daughter to do carbs. They are simple and to many people are intimidated by them.

Seeing where that crack is I would definatley use JB weld on it. No since throwing out a good carb set for something like that. I am guessing that if the crack was seeping and the vacuum draw from the motor was drawing the fuel from the crack into the motor and causing a rich/backfire condition.

 

[lmuss53]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

http://www.youtube.com/watch?v=o5cxBMDezuU

Watch this before you rip into them again, carb rebuild on '80 something 115 Johnny. It could be a little more concise but it is helpful in my opinion.

I've read that we should not soak our carbs because it strips some factory coating off of the body.

 

[emdsapmgr]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

Backfires are common if two of the plugwires are switched. You said you covered this already. Did you check the orange color coded power pack wires that feed the coils? They are easy to switch.

 

[mikesea]

Re: Like It Never Ends: Carb Issues

Re: Like It Never Ends: Carb Issues

another thought,make sure your timer base under the flywheel is rotating smoothly,with the throttle arm