20hp Merc help – Part III

Hopefully not of a 9 part series…

IDO walked me through fixing the recoil spring, then the impeller. Then, I made the mistake of not hooking up the spitty hose thing and water got into the engine compartment. It would start but would die. Gave up for the night.

Today I put fresh non oxy in a clean tank, new merc oil, new NGK plugs, and tried to fire it up. Now it will only do one or two pops and won’t start. What I noticed is that when I pump the primer bulb it doesn’t get hard and gas flows out of the top right (little hole?) in the carb. Thought maybe the float was stuck – tried tapping with a wrench but had to stop because it is my son’s 4th birthday.

Help. If possible, a non-rebuilding the carb hack.

For the record, I do not like this engine. It is too loud and heavy for my 14′ boat. My 4.5hp putts me around just fine for 95% of my needs. However, my wife was able to get the 4th off for the first time in years and my 4.5 can’t keep up with the boat parade on the in-laws lake. Need it to run for at least one stupid weekend.

How far up did the water get in the engine?

Did you take the plugs out when you let it dry?

I had the hose disconnected at the point where it goes into a fitting and into metal at the top, so it kind of flowed down over the parts since the impeller was kicking ass. The water did not go too high in the case as it didn’t run long, there are drains here and there, and the metal wrap was off.

Plugs were not out. Should I pop them out now?

Edit: took out plugs and put a box fan on it for the night.

if you have gas coming out of the vent hole in the carb,either the float is stuck,or the needle and seat have a chunk of crap in it,
it will need disassembled to be cleaned up properly.

that carb is not complicated at all,once removed,remove the four screws that hold the float bowl on,remove the float bowl,pull the pin out of the float paying attention to how it sits on the pin and how the needle is hung from it.

using brake cleaner ( in my mind it does better than carb cleaner ) spray through the needles seat hole,also the little brass jets you will see in there.
put it back together and dont over torque the screws.
it should run fine if you put everything back together right.

that motor may be noisy,it may be heavy,but that motor puts out a lot of power for a twenty horse and its not hard on fuel.
I had one two years older than yours,it would push my eighteen extra wide extra deep sixteen foot Alumacraft flat bottom at twenty seven mph according to my gps.

one last thing,if you put surface gap plugs in it,those are wrong,it will not run on them,put the old style back in,the ignition system in it is not designed to fire those surface gap plugs,period.

I had no idea i could choose what plug to use – i have always just brought the old one in or asked them to look it up in the book. How do i find the correct plug as NGK just shows surface gap ones?

I stand corrected,dang it !I apologize that I was wrong,they changed the ignition system on that motor sometime in ’77 or ’78.
yours does take the surface gap plugs,I was going off of memory on mine which did not take surface gap plugs and wouldnt even start on them.

too many times those surface gap plugs are a direct crossover to the conventional type and are installed and then the motor wont run right if it even starts as the gap is too wide for the ignition system to fire.

again,sorry for the confusion !

Bummer – I was hoping this was the reason it is always a PITA to start…

Slipped out before the kids woke up and cleaned the needle. Bulb pumped hard so we will see when I can hook it up to water again later.

the way I started mine was to place the choke in the on position,pull the starter rope through three compression strokes.
move the choke to off,throttle to start and give it a rip,usually started and stayed running with no more than two pulls of the rope.
once it was started for the day it would start the first pull every time without choking it again unless it was more than three hours without it running.

another thing that makes a difference in how easy it should start is that it is tuned correctly,ie,timing,carb adjustment,crankshaft seals in good shape etc.
it also makes a difference in how often it is being run,if it is only run once or twice a season,any motor can be a little bit stubborn in starting the first few times out.

Your carb probably doesnt have as many passages and ports as mine did, but taking some 30# mono to all the nooks and crannies really helps make sure it’s clear. Gunk fills up and needs a lil nudge and line won’t damage it.

Here’s my before and after in one passage

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Couple pulls and it is purring as well as it ever did! Thanks! I wonder what it would have cost to pay to have the recoil spring fixed, impeller replaced, carb cleaned, and plugs put in…

The motor does not get a lot of use which is part of the problem. My ritual (and my dad’s before me) has been pull with choke on till it pops, turn choke off, and it usually starts the next pull. The biggest problem I have had is when it is cold in the morning, or just cold in general, and it can be almost impossible to start.

I would use this engine more if I had a bow mount trolling motor, but they are super spendy. I had a small one in the back that died and I’m not keen to replace it because it (with battery) added so much weight to the back of the boat even with the gas tank in front of the second seat. The 4.5 isn’t awful for trolling or maneuvering here or there, it just blows that I can’t even plane out to get anywhere fast.

good job tindall !!
you would have paid a couple of hundred easy plus parts to have all of that done here.

if you are having that much trouble starting its when cold,take a look at the choke plate when its in the on position,see if you can see a gap between the choke plate and carburetor.

if there is a fairly good gap there,it may be that the choke plate is too loose on its mounting screw,some of those choke plates were spring loaded and could be tightened down to close the gap up a bit.
dont over due it if thats the case,you want a tiny gap there to let air in so it wont be so prone to flooding when choking it.

if you can,post a side view picture of the choke plate in the on position.
I should be able to see if its out of spec and if in fact it has the type of set up I think it has.

Nice job!

For what it’s worth, I find that Sea Foam helps a lot in engines I don’t use often. I mix it in the gas religiously, but I also spray Sea Foam Spray directly into the carb and run the motor out of gas if I know it’s going to sit a while.
This works well for me.

A couple hundred!? I must have been going to the ripoff places all my life.

For some reason I have never thought of running the gas out of my outboards even though I do it for everything else. Duh. I use seafoam sparingly, but mostly swear by quality or brand oils and fresh non oxy gas only – ever, ever, ever.

I will try to get a pic of the choke – I thought I saw a slider with a set screw that lets you adjust it.

My one question after all this is: what is the right way to reinstall the recoil spring? First I tried hooking the bended end and feeding it in which didn’t work at all. Then I tried superman grabbing it while pulling the coil smaller, wrapping the end a couple times, pulling, wrapping, etc.- but I could never get it small enough and cut my hands a few times. After exhausting my full vocabulary of swearing I finally took a 2×4, put 2 finish nails in it about 1″ apart, hooked the inside loop I had formed on one nail while the other nail braced the spool. I stepped on the board and wound and wound until it was small enough to drop in the recoil thing, clamped it all together with vice grips, carefully lifted it off, dropped it in the plate thing and let the grips off. There has to be a better way.

As far as winding the spring, once you have it wound up wrap it in three places spaced evenly with small diameter wire or woven tape.

Drop it in place and remove the wire or tape while holding the spring down as it can jump back out on you if you are not careful.

Iowaboy1 wrote:

once you have it wound up

Yea, but this is the million dollar question – how do you get it wound up?

lol, the way you did it is just fine but remember to wear leather gloves.
where I work part time we have a winder purpose built for that task,it has a locating pin on the base,a pin in the winding handle and a shield in case of sudden breakage.
once its wound up we wrap it in three places with safety wire and drop it in place in its cavity making sure the outer bend or tang is engaged in its slot then cut and remove the wire while holding down pressure on the spring so it doesnt escape its confinement.
if the inner coil is bent right,it will engage the pulley or hub when you put it in place.
remember to coat the spring with light oil.

wind the pulley several turns and put the rope through the hole and tie a stout knot in it.
if done right the handle will stop tight against its resting place when you let go of the pulley,if you have it wound too many times,the spring will bind before you get the rope pulled very far and it will break if left this way.
the first few times can be a trial,just take your time doing it.
also make sure you have the right amount of rope as well as the right type of rope.

winding by hand you have to be extra careful,it takes practice but can be done rather easily.
I would love to have a dollar for every time I have wound one up by hand the last forty years or so in chainsaws,outboards,weed eaters,etc etc.
the first one I did was on my five hp techumseh mini-bike engine when I was ten or eleven years old,when it broke dad told me I had to figure out how to fix it and just do it,two days later I got to ride it again ! and no,no one helped me do it,I bled a lot too.