1988 yamaha pro50LG hard cold starting

[Collinsje308]

Hi everyone,

I have looked through dozens of pages of this forum trying to find a solution to my outboard problems. I have a 1988 PRO50LG 50hp, tiller handle model outboard, I have had this motor for just over a year now. I had some problems with it last fall that was most likely carb related as it would run rough intermittently. I replaced the things i could (fuel lines, fuel filter, fuel pump, spark plugs) and then I took it to a marine shop local to me (Lacrosse WI) and had them go through the motor and re build the carbs, so they are clean for sure. They also check compression and timing and spark and said everything checks out good. Now the motor runs like a top, after I get it started. Before i took it in it started kinda hard on a cold start but nothing out of what i consider ordinary. 2-3 times turning the key with the choke out and it would pop off.

However now it starts cold extremely hard, after it fires it will run just fine and start back up after i shut it off by just bumping the key. I cant afford to take it back to the shop and have this dealt with as i already got soaked for almost $1000 dollars the last time. Would any of you have any suggestions as to how to make this motor start easier? i would greatly appreciate it.

Thanks,
Jesse

[99yam40]

give us your starting procedure.
Do you open the throttle some when you cold start?

[Collinsje308]

My starting procedure goes like this. Prime the bulb till rock hard. Pull out choke. Turn throttle to start or just past. ( Can't open the throttle up any more than that in neutral). Turn the key over. (5-10 seconds). Push choke in. Turn key over. Pull choke out. Turn key over (it might fire here). Basically repeat this 2-4 more times. turn key over again and it might fire here again but will only stay running at 1500-1800 rpm for about 2-3 minutes. Then I can throttle it back down.

[99yam40]

So are you saying that the electric choke does not work when you push in the button/switch?
I am not familiar with a tiller 50 that old and I do not see anything in the carburetor parts breakdown that looks like a electric choke solenoid .

but I must be confused with another thread ,rereading you post you did not mention anything electric

sounds like it is normal on the old manual choke motors

[Collinsje308]

My motor does not have an electric choke. Just the old style manual pull out choke on the lower cowling.

Ok i was just looking for anything that might make this motor start easier, as in my mind it does not seem normal. As i also have a 1978 evenrude 35hp, with only a pull start that will fire right up on the second pull no matter what, even after sitting in the garage all winter.

So it seems to me that there should be a way to get this yamaha to start cold a little easier. Im always worried about running my battery dead before i even get going on the water.

[Collinsje308]

Another question.....Would adjusting the air/fuel mixture screws on the carbs help this problem at all? as it runs pretty rough till it warms up.

[panasonic]

So you are saying that it was a bit hard to start, took it to a shop, carbs cleaned, it started much better for awhile, now it is very hard to start. Is this correct??

So something must have changed since the carbs were gone through. My guess is they are getting dirty again. That engine should not be that hard to start.

See item #6 and #7
https://www.boats.net/catalog/yamaha...0lg/carburetor
That rubber plug must be in place and that jet must be clean.

Also there is a passage between the main jet#4/5 and pilot jet #6 that is easily clogged and would make the engine hard to start.

During your start process why do you turn the choke on and then off again? Does it flood if you leave it on and continue to crank?

[Collinsje308]

So you are saying that it was a bit hard to start, took it to a shop, carbs cleaned, it started much better for awhile, now it is very hard to start. Is this correct??

So something must have changed since the carbs were gone through. My guess is they are getting dirty again. That engine should not be that hard to start.

See item #6 and #7
https://www.boats.net/catalog/yamaha...0lg/carburetor
That rubber plug must be in place and that jet must be clean.

Also there is a passage between the main jet#4/5 and pilot jet #6 that is easily clogged and would make the engine hard to start.

During your start process why do you turn the choke on and then off again? Does it flood if you leave it on and continue to crank?

No, it starts much much hard since i got it back from the shop, it started much easier before. It never started easier after i got it back from the shop. The carbs were cleaned and rebuilt.I cant really imagine that they would get dirty immediately after being completely rebuilt.
I turn the choke on and then off again out of fear that i am going to flood it. That is how it would start before i took it to the shop, pump bulb up, pull out choke, turn it over, push choke in, turn it over, pull choke back out and turn it over and it would pop right off every time.

I took it in because i had some intermittent running problems when it would run fine for an hour then lose power and run really rough but it wouldn't always do this.

[99yam40]

I would check to make sure the coke is closing off all of the way when you pull the lever out.
then try not pushing it back in after the first try to see if that helps.
the motor has to get some air along with the fuel at start up so it is good to make sure the throttle plates are opening some in the start position

[Collinsje308]

I checked last night to see if the choke plates were closing all the way, and they basically are the choke on the #1 carb (top) has less than a 32nd of an inch of "play" in it other than that they all close completely. I will look tonight to see if the throttle plates are opening some in the start position.

[Collinsje308]

I checked to make sure the throttle plates move/open some at the start position and they do.

Anybody else have any other ideas i could try or things I could look into?

[panasonic]

I would suggest you go back into the carbs and see what is going on in there. If the engine is now harder to start AFTER the carbs were rebuild....then most likely there is probably something up with the carbs.

It would not be the first time, nor the last, that it took more than one attempt at getting a set of carbs cleaned and adjusted right.

[boscoe99]

Hey Pan, how you doing up there?

Air line industry is in the toilet. Whole economy is looking grim. Read that global commercial aviation is down 96%. Only way Boeing can survive IMO is if the USG props them up. They were hurting before Covid. Covid should be the final nail in their coffin.

Take care and be well.

[panasonic]

Hey Pan, how you doing up there?

Air line industry is in the toilet. Whole economy is looking grim. Read that global commercial aviation is down 96%. Only way Boeing can survive IMO is if the USG props them up. They were hurting before Covid. Covid should be the final nail in their coffin.

Take care and be well.

Still working until April 20, then forced vacation for Two months...at least. We are still flying 10% of normal schedule. Airplanes parked all over the place. Small number of mechanics will be kept on to do the storage maintenance...which is going to keep them very busy.

Hopefully this will start to turn around in a few months...need a vaccine for this dirt sooner rather than later.

Everybody please be smart and safe!!!

ps. Boeing is to big to fail.

[99yam40]

I checked to make sure the throttle plates move/open some at the start position and they do.

Anybody else have any other ideas i could try or things I could look into?

OK back to the thread.

for a motor to fire up, it needs good compression, good spark at the correct time, and the proper fuel to air ratio.
you said the compression was OK, but never said what the reading were.
It is a very old motor
something is lacking, just need to figure out what it is.

are you sure the motor is spinning fast enough?( good battery and starter?)