85 120, good high end, bad idle & dies

[tal]

Ok I need a little advice with my new to me looper. First a little history. Bought motor and installed on my little bass boat. All new fuel lines, fuel filter, carb kits with floats adjusted correctly, new fuel tanks, bulb, new spark plugs, and a freshly sealed gearcase. I've gone over the lync and sync 2 times. VRO pump removed by previous owner with what appears to be the correct pump going by numbers on this forum. Compression 128-145 on all 4 cylinders.

Problem: Start engine at launch, acts real cold natured and takes a good amount of warm up lever and pressing in the key to stay going. Smokes like crazy with correct amount oz of oil per gallon of fuel (red choke lever is in correct position). Sounds like it's missing and hissing at me. I let it run for a few minutes while buddy parks truck. Put engine in gear and it wants to die. Start up again with warmup lever and choke, put in gear and attempt to throttle up and it wants to slowly sputter down and die. Pushing in key helps to get it going. Infact, that's the only way I was able to get it to plane. Once going, runs good, strong and smooth all the way up to full throttle.

31.5 miles later I run out of my first 6 gallons of gas at idle speed while taking a leak into the lake. Switch tanks, prime bulb until hard and same story as above. Seems like my idle jets might be clogged but not sure as I ran a fine wire through all the jets after they soaked in dip over night. Also seems like it's running really rich at idle with all the smoke fuming us out of the boat. If I come off of plane and idle for a little I can plane back up with no bogging or hesitation as long as I can keep the bumpy idle going. Sorry for long post, any thoughts?

 

[kenmyfam]

Re: 85 120, good high end, bad idle & dies

Service the carbs/fuel system.

 

[tal]

Re: 85 120, good high end, bad idle & dies

ken, anything in particular in the carbs, like the low speed jets? I literally just did all of this 1 month ago. The entire fuel system is new except for the fuel pump, priming lines, and fuel manifold. The fuel primer lines ("choke") lines are in perfect pliable condition, the manifold appears to be flowing plenty of fuel as is the fuel pump.

I can be going 30 mph and slam the throttle down, the boat feels like it literally jumps out of the water and pulls very strong all the way up to 64mph, 62mph today with 3 people fully loaded.

Also I just installed a new tach as the old one from the donor boat was sticking around. The old Faria tach was set with the arrow facing to 4 so I set the new tach to 4 initially which seemed wrong. It appeared to display almost 2x the actual rpm of the engine, going by sound. The 6P setting on the new tach looks right, but only reads a full throttle of about 5200-5300 rpms. This is with a 21 pitch prop on a Skeeter SD80 15.7ft boat. I'm fairly certain the tach is set right but WOT rpms look low. Doesn't feel like there's any problem on top end power.

 

[oldrudedude]

Re: 85 120, good high end, bad idle & dies

Certainly sounds like a low speed jet issue. How does it run on muffs? What do the plugs look like after idling? Might you possibly have a vacumn leak?

 

[tal]

Re: 85 120, good high end, bad idle & dies

Idles fast on muffs, but from what I've heard this is normal for these engines. Not sure what the new plugs look like, just installed them yesterday and didn't check after the run today. Not sure about the vacuum leak.

 

[tashasdaddy]

Re: 85 120, good high end, bad idle & dies

pushing the key in, enriches the fuel/air ratio. did you use the complete carb kit, and did you remove all the jets and clean them and their ports.

also you need to set your idle high, on muffs, then fine tune it on the water, with the motor in gear.
read ethanol, carb cleaning, decarb and compression check. >>>> http://forums.iboats.com/showthread.php?t=299680

your compression has a very wide spread. 17 psi. i would definately do a decarb.

 

[tal]

Re: 85 120, good high end, bad idle & dies

pushing the key in, enriches the fuel/air ratio. did you use the complete carb kit, and did you remove all the jets and clean them and their ports.

also you need to set your idle high, on muffs, then fine tune it on the water, with the motor in gear.
read ethanol, carb cleaning, decarb and compression check. >>>> http://forums.iboats.com/showthread.php?t=299680

your compression has a very wide spread. 17 psi. i would definately do a decarb.

I did use the complete carb kits, all genuine evinrude parts. I removed all the jets with a ground down screw driver. I cleaned all the jets and ran a fine wire through them, held them up to light and could see through each little hole. I then set floats to +- 1/32 of an inch from sealing surface as manual calls for. I actually ended up having 2 bad plastic bowls and had to order them, but these plastic carbs were exceptionally clean, compared to aluminum ones I've done in the past. I will look into doing a decarb to try and even out the numbers. I'm just a little stumped with the rich smoky idle issue and bogging after doing a complete carb over haul.

 

[reeldutch]

Re: 85 120, good high end, bad idle & dies

if you hit the primer to keep the motor from stalling in gear or to get it going to plane of, your fuel to air ratio is off.

dont jump ahead we will get to the smokey part later.

your engine at this time is asking for more fuel to run normal.(its running lean) not a good thing for a 2 stroke .
in fact at high speed its not only the main yet that suplies the fuel to the cylinder all yets low speed and intermidiate all let fuel into the crankcase.
so if your low and intermidiate have problems you might lean it out at high speed to, but you dont even know it.
thats a great scenario to score a cylinder.

back to the carbs if you are sure your carbs are spotless you might have a air leak.
could be trothle shaft, crankcase seal, fuel hose.
also these engines dont like to idle cold make sure its getting warm around 140.

i would personaly check the carbs first than all the fuel lines. no guess work you got to be 100% certain of your work or you will be running in circles.

can you pinpoint it to 1 cylinder?
do a cylinder drop test.
might tell you wich cylinder is not contributing as much or at all.

 

[tal]

Re: 85 120, good high end, bad idle & dies

I guess I'll start tearing apart the carbs again. I'm almost certain I'll find nothing clogging the jets, but I'll take a look again. Think I can reuse the gaskets in between the bowl and the mains? They're only about a month old. I might start by removing the idle and intermediate jets and looking at them since they're accessible from the front of the carbs.

I did leave an important part out of my original story. This was actually the 2nd time I had the boat out since I redid the carbs and installed the engine. The first time produced similar results, not wanting to idle and smoking alot. This was when I adjusted my idle so it would run a bit faster. After messing I proceeded to plane off for the first time, slowing engaging throttle but the boat just pointed straight up, engine never bogged, it just didn't get on plane. So I backed down to idle and checked bulb and fuel. Both were good to go and I cranked back up, smoked a bunch of oil, and proceeded to plane again. This time it got right up with no problem. So after all of this I went just this last weekend to fine tune and ran into the complete bogging/not wanting to idle episode. So something happened within 2 weeks time to clog my carbs, or mess up whatever got messed.

 

[tal]

Re: 85 120, good high end, bad idle & dies

Ok I think I've got some good news. I went out today to start some work on the motor. I popped the cowling off and took all the bolts off the air silencer. I noticed a bunch of fine little debris, like black sand but softer. It was in the air silencer and throat of the carbs as well. I could wipe my finger through the throats and see the bits left on my finger. The debris appear to be the foam which is glued to the inside of the cowling. I think this is some sort of sound blanket, if I remember correctly. My plan is pulling the idle/intermediate jets and cleaning them to try that first. There appeared to be little things inside the jets and blowing on one of them backwards actually plugged the thing up to the point of me not being able to see light through it. I will clean the entire engine area to make sure I'm free of debris, clean the silencer, and clean all that decentagrating foam off and try to run it again. If it still acts up then I'll go through the carbs again. Anyone ever seen this foam come off and get sucked up like this?

 

[peterskeeter]

Re: 85 120, good high end, bad idle & dies

Put a wire brush on a drill and remove all of the foam from the inside of the engine hood. That foam is very old and does nothing but cause trouble. You won't notice a difference with the sound.

 

[kenmyfam]

Re: 85 120, good high end, bad idle & dies

Dump the foam, clean the carb's again, go boating.

 

[tal]

Re: 85 120, good high end, bad idle & dies

There was definately some stuff in the idle/intermediate jets so I cleaned them out and reinstalled. I also cleaned all kinds of little foam debris that were stuck on the wet side of the air silencer. Cleaned all the stuff out of the cowling so no more foamies.

It seems to idle a little better but overall, my low speed issue still exists. Launched the boat, smokey rich idle, boat planed fine. Ran for a few miles then stopped to check idle speed, which was low. Attempted to adjust with boat in gear, trolling at idle speed. Idle screw made some difference but hard to tell as the motor is not running smooth, yet doesn't seem to be missing.

After coming off plane the engine shows hardly any signs of smokey rich fuel, but after idling for a minute or 2 it begins to load up heavy with fuel and smoke. I'm guessing fuel as it seems smokey rich. After trolling for a couple minutes and setting the idle speed, I attempt to plane boat and it wants to bog down, as if its not getting fuel? Perhaps it's flooding? I can restart the engine with warmup lever put it in gear and if I hit the primer it will kill the engine, so it doesn't appear to be running lean or starving for fuel.

I've been through the carbs 2x now and double checked floats levels, which are in spec. I can't figure how it's getting all the extra fuel at idle but runs perfect on top end. The only thing I haven't done is checked thermostats. Could it running a little cool cause all this? Running fine on plane then 2 minutes of idling start a bunch of smoke and rough bouncy idle?