1990 50 Johnson keeps dying

[atistang]

J30ELE55

I bought this engine from a friend last year and had no major issues all last season. It has always ran a little on the rough side at low RPMs.

I looked in the shop manual on how to adjust the low speed mixture on the carbs and went out tonight to fire it up for the first time this year.

First I pulled the spark plugs and regapped them to .030"

Then I replaced the white in line fuel filter under the engine cover. ( I noticed it still had fuel in it from last season, ethanol free)

I then tried to start it. After about 3 15 second long cranking sessions I realized that I forgot to hook the fuel line up. So I hooked the fuel line up and primed the line with the bulb.

After much cranking I finally got it to hit a few times then die. I primed the bulb again and same thing. I finally got it to run by giving it some throttle and let it run at about 2k rpms for a few mins. I brought it down to idle and it seemed to idle even rougher than last season, so I started giving the screw on the top carb a little counter clockwise (leaner) and it smoothed up a bit. I kept going until it started to get rough again and backed it the other way about a 1/4 turn. I then did the same with the bottom carb and before you know it that thing was purring real smooth.

I had the drive in a 55gallon drum full of water and put it in gear to see where it idled in gear. I was idling real nice about 900rpms and suddenly it started to slow and then died. I struggled to get it running again. So I decided to start from scratch. I turned both fuel screws in all the way then backed them out 1 3/4 turns. I can hardly get the thing to run now. So I put them back where they started which was about 5 1/2 turns (this was alarming to me) and got it to start and run with a little throttle, but not idle for more than 20 seconds or so before it dies.

One thing I noticed was the fuel filter hardly has any gas in it. By that I mean if I look down in it with a flash light I don't see any fuel. I pulled the fuel line off the filter and cranked it a bit, it did not produce fuel...


So, is it possible I need to prime the system in some sort of way more so than the primer bulb?

Is it possible I damaged the fuel pump with all the cranking before I had the fuel line hooked up?

 

[lindy46]

Try squeezing the bulb when it starts to die and see what happens. Start with the idle screws opened about 3.25 turns.

 

[atistang]

I'll give that a try. If I disconnect the fuel line at the filter then squeeze the bulb I should get a decent amount of fuel coming out, correct? After sleeping on it I am thinking maybe I have a clog somewhere.

 

[lindy46]

If the motor runs when you squeeze the bulb but dies when you stop squeezing, you have a bad fuel pump.

 

[atistang]

If the motor runs when you squeeze the bulb but dies when you stop squeezing, you have a bad fuel pump.

Is it possible that the fuel pump could be getting tired to the point it pumps fine at higher rpms but not enough at low rpms?

I had it idling good in neutral. So the past few days when I have the time I've been going out, starting it, letting it idle for about 10 mins, let it idle in gear for a min or two, then back to neutral, give it a few revs to be sure its no loaded up, then shut it off.

It did fine with this 3 times, then yesterday when I put it into gear it started to lose rpm and within about 20 seconds it died and wouldn't start. I observed once again the fuel filter was empty.

I am trying to locate a spare fuel tank to try as I did have a clog in the pick up tube and I'm not sure I got all the debris out. It is an older aluminum tank and the tube is welded in with a screen at the top. So when I pull that screen some stuff falls back into the tank.

 

[racerone]

J30ELESS-for your model would be a 30 HP motor?------Many folks do not understand how these PRESSURE operated fuel pumps work.--------I am not sure how these pumps can become tired !!------The pressure input signal might be too low I suppose..----I would say test run with another tank and hose.---Possibly an air leak on hose , hose fittings or inside your fuel tank.

 

[atistang]

J30ELESS-for your model would be a 30 HP motor?------Many folks do not understand how these PRESSURE operated fuel pumps work.--------I am not sure how these pumps can become tired !!------The pressure input signal might be too low I suppose..----I would say test run with another tank and hose.---Possibly an air leak on hose , hose fittings or inside your fuel tank.

Sorry its a J50TSLE

I have a spare tank lined up to try out soon. If that doesn't fix it then I am thinking I'm going to replace all the hoses next.

 

[racerone]

Verify your model # as this is confusing here !

 

[ct1762@gmail.com]

I think you mean J50TLES??

 

[oldboat1]

New fuel pump diaphragms are very flexible. As the pump ages, the diaphragm can take a set, with the consistency of the diaphragm closer to cardboard than to rubber. Efficiency is reduced. Choice is to replace the diaphragm or the pump.

 

[atistang]

I think you mean J50TLES??

Part of the tag is missing but what is there is J50TSLE It's an SPL

 

[atistang]

New fuel pump diaphragms are very flexible. As the pump ages, the diaphragm can take a set, with the consistency of the diaphragm closer to cardboard than to rubber. Efficiency is reduced. Choice is to replace the diaphragm or the pump.

That's what I was wondering.

So today I go out and start it, it fires up and idles decently. I let it idle for 15 mins or so. I give it a couple revs and it comes back to a decent idle, so I throw it into gear and within 10 seconds or so it idles down and dies. I pull the spark plugs and they are fouled. So I clean then and put them back it, will a little bit of cranking it starts back up and idled. So I go back to the mixture screws. Turning the top carb in about a half turn seemed to smooth it out a bit. As soon as I turn the screw on the lower carb it bogs and dies, from 1/8th turn. I set it back and start it back up, tried going the other way 1/8th, same thing. Engine bogs then dies. Set it back to where it was, tried idling in gear again and same thing, it slowly idles down, bogs then dies. I start it back and it idles good just long enough for me to walk away from the controls. Then it stumbled and died again. Plugs were fouled again. I had a brand new set of plugs, so I gapped them to .030 and put those in. It started and then died. I crank for a bit and can't get it to start, so I hit the primer on the ignition switch and it starts up. This time idles for a few mins then dies again. I pulled the plugs and they are dry....

Fuel filter is dry. I pump the primer until it fills the filter. This time I get it started with about half throttle, it won't hardly run below that. I said screw it and went through the Sync and Link procedure. After that I get it to start, but still won't idle. At this point I was out of daylight so I had to stop.


Right now my thoughts are

Maybe the pilot (slow) jet is getting plugged on one of the carbs?

The fuel pump is weak and struggles to draw enough fuel? Seems odd that it tends to work decent from a cold start, but then get worse the longer the engine runs, but then that also seems odd that a gummed up carb would do this too.

Ignition coil is going? I've had this on cars, dirt bikes, lawn mowers. Once the coil gets hot it starts acting up...

I think I am going to go ahead and rebuild the carbs and replace all the fuel lines while I'm at it. If anyone has any recommendations on brand or where to get hose or the rebuild kits I'm all ears.

 

[oldboat1]

OMC/BRP kits usually come with the floats and instructions, so a good choice. I wouldn't start with the carbs, however. Measure spark first on each lead with an adjustable tester (open air). Set it for a half inch and work backwards if necessary. Also do a compression test to see what you have. Post what you find for spark and compression.

 

[lindy46]

Did you ever try squeezing the bulb when it starts to die?

 

[atistang]

Did you ever try squeezing the bulb when it starts to die?

Yes.

When the bulb gets stiff I can squeeze it very hard and force more fuel into the filter. Do this when it starts acting up has no change in things that I've noticed. But it's hard to tell for sure because once it starts acting up it dies suddenly.

I can say as of last night squeezing the bulb and filling the fuel filter, if I get it started back up it will still die as soon as I let it try to idle. So I'm leaning towards it not being the pump. But idk as this is my first time owning an outboard with VRO.

 

[atistang]

OMC/BRP kits usually come with the floats and instructions, so a good choice. I wouldn't start with the carbs, however. Measure spark first on each lead with an adjustable tester (open air). Set it for a half inch and work backwards if necessary. Also do a compression test to see what you have. Post what you find for spark and compression.

I ordered the adjustable spark tester, didn't even know that was a thing. I'll check compression tonight if I have time after work.

 

[atistang]

Also I have determined the full model number of my engine is

J50TSLEC

 

[racerone]

Post compression test results.-----Post results of spark test too.

 

[atistang]

Compression was 142psi and 148psi cold

I redid the sync and link according to this video as I have realized the manual I have is for 3 cylinder engines.

https://youtu.be/qigy9Ryha2A

So where that leaves me. I can start the engine and it will immediately die. I can give her some throttle and it'll run but the rpms surge and eventually fall until the engine dies. If I keep the revs higher than 3800rpm or so the engine will keep running. When at lower rpms I can keep it running by pushing the key in.

So with my knowledge of things, I'm thinking there are some things clogged in the idle circuit of one or both carbs. I'm going to see if I can get some carb rebuild kits locally tomorrow and rebuild them.

I'm still going to test the spark when the tester arrives, unless I rebuild the carbs before then and that fixes it.

 

[juno pierrat]

model number shows it a 1998, careful/don't run at high rpm's in neutral could cause a runaway engine