Evinrude 20 stalling

[swedish johnson]

So , my noisy 86-91 Evinrude 20, is now a little quieter for changing to a 50-1 fuel mix, but now i have an issue. The engine ran great on 100-1 mix, starts first pull and runs clean from tickover all the way to WOT. After changing the fuel mix, it often takes more than one pull to get it started, but more of the problem is stalling when opening the throttle at just over tick over. If you go real (really) slow on the throttle you seem to be able to get through it but seems to be a noticable rough spot. Runs sweet at high revs. Just this problem of coming back down to tickover trolling speds and stalling on throttling up.Makes manouvering in the marina a bit of a crap shoot. All my fuel is double filtered and run through a 10 micron water seperator. I have just removed the motor to test an old 6hp twin i have had in storage, so i can only test run the 20 with some flush muffs. I dont want to go messing with carb jets etc without checking in here first, as you guys seems to have been through all this before and may have a better idea of what first to look at.
Another side issue is its damn loud, i already have an issue with hearing, but i dont want to be driving around with ear muffs. Anyone tried any modern under bonnet(hood) material to lessen the noise? Im very tempted to line the cowl with thin lead sheet.......
Thanks in advance. Ian

 

[fireman57]

Try running it in a barrel to quiet it down. Sounds like you may have some crud in a low speed jet. also if it is loud on the water you could have a bad powerhead base or exhaust gasket bad. You definitely want to run 50:1 mix.

 

[swedish johnson]

Thanks for reply. Gaskets are fine. The engine seems to run at a noise frequency that totally gets my tinitus turned up! I will pull the slow speed jet, once i find out where that is on this model......
Cheers.

 

[racerone]

???----The slow speed mixture adjustment is right there above the throat.-----The high speed jet is hidden / screwed into the carburetor bowl.

 

[swedish johnson]

I was expecting, having looked at a manual, to find a locking nut with the needle adjuster running inside it. What i have is a straight out threaded part with a needle in the end. The outside end was machined to take a plastic knob by the looks of it, as there is no slot to take a screw driver in the end. It was impossible to move by finger pressure, had to use small vice grips to get a grip on it. Took 22 revolutions to come free. The needle has the smallest of shoulders on it, hard to see but i can feel it. Looks absolutely spotless on needle and from what i can see. Hard to tell just how far to wind it back in, and how hard without damaging anything. Seemed "stiff" at 24 turns, so i backed out a turn and a half from there, that seems to be a basic setting to start from, would that be about right? Cheers.

 

[AlTn]

to clarify which carb set up you have try the site mar ine eng ine dot com. < 1 word >...look up the '86 and '91 20 hp. carb diagrams...which is more like yours?...the only late model < 1991 > 9.9 hp. I've fooled with I had to open the idle mixture needle a full 5 turns for it to start....sound deadening..I've done this to a '71 25 hp...it was a material that has a foil backing on each side and a blanket- like material sandwiched between...just used some spary adhesive for auto upholstery work made by 3M on the interior shell of the cover and it adhered well...this was only a couple of years ago, but it's still there

 

[swedish johnson]

There was some numbers on the carb, i will do a check using that, those diagrams all start to look the same after a while. My local auto part store has some of that aluminum faced foam, i will grab some next time im passing.
Postage costs from the states have gone crazy, so will probably order new carb re-build kit and needle at the same time if the engine has the same problem when i put it back into use.

 

[swedish johnson]

I keep coming back to a 86 year with the block number BE20 BFL CD C. I was told it was a 91. The 86 carb diagram has the CD year, but the bowl has a front screw where i have a pipe going in, which seems to be a later thing. There is a marking AL63 0008 on the top of the carb body, but i do not know what this refers to.

 

[AlTn]

looks like it's a Belgium derated electric start...20 hp...1986 model year....is the "pipe" going into the float bowl a fuel line nipple?..if so, it should unscrew just as a bolt would and have a small gasket between it and the fuel bowl

 

[oldboat1]

have to ring in (or buzz in) for a fellow tinnitus sufferer. Hood liner works well (foil side facing engine). The parts store should also have 3M contact cement or similar (spray can). Cut pad to fit top/sides of cowl. Spray hood and foam and let it set up for the specified time, then press in place exactly where you want it.

on low speed needle setting, I've usually found setting leaner to tune (clockwise) is more effective. sometimes seems counterintuitive. 1/8 turn or so at a time, then let engine catch up. When engine wants to stall, back out about 1/4 turn. Should be pretty close to running setting. On a couple of my motors ('80s motors), have to set the mix richer for easy starting, then lean it out again when engine warms up.

 

[swedish johnson]

Thanks for ringing in and good to know the foil blanket should help keep the noise down. I did try to post a pic of the carb in question, but i keep getting corrupted file message. Anyway, there is a hose from the choke running to a nipple on the float bowl if that help.
It had been a great first time starter and good idler, why i was a bit miffed at the sudden stall issue. Hard to think it may be crap in the slow speed jet with all new tank hoses and filters, so could just be a tuning issue, i dont believe it has been run as hard as i ran it last few outings as it was used on a very small lake on a very small boat.

 

[oldboat1]

Your model may have an electric primer on it (reference to that mystery line). Might find a diagram of an '86 20hp carb (or '91), electric start model: See AITn's post (#6). The carb is not difficult to clean/rebuild. It wouldn't be remarkable at all to find the low speed openings need to be cleaned (top of the carb, under the expansion fitting up on top). Recommend a carb kit, as you mentioned earlier -- probably don't need a needle unless it's bent up or broken.