30HP johnson hard warm start

[djp2010]

Hi im new on here and i am new to outboards. i recently purchased a 1996 30hp Johnson that is on a 18ft flat bottom. Engine runs great and starts right up when cold but after running for 15-20 min.,it is hard to start-i mean like 20-30 pulls. alot of times ill pull the plugs and find no fuel on them-sometimes there is. i went through the carb,rebuilt the fuel pump,new fuel tank,line,bulb. Im real close to giving up, any advice, pointers,secrets would be appreciated. thanks

 

[ondarvr]

Re: 30HP johnson hard warm start

What is your method of starting it when its warm?

 

[djp2010]

Re: 30HP johnson hard warm start

Well ill make sure the ball is hard and just start pulling i guess-

 

[jasper60103]

Re: 30HP johnson hard warm start

2 things I would try.
Even though it sounds like a fuel issue, I would check spark with a spark tester when it's hard starting.
Also, squirt some fuel mix in the carb when it's hard starting and see if she will turn over for you.

 

[ondarvr]

Re: 30HP johnson hard warm start

Try using the choke as if it was cold and if needed turn the throttle up slightly.

 

[djp2010]

Re: 30HP johnson hard warm start

Im getting good spark when warm and have sprayed fuel mixture into carb and still no go-once in a while it will back fire-after that i have to take a break before i have a heart attack from pulling. I have twisted throttle 1/4,1/2, and wide open-usually after pulling several times(20) at wide open it will fire up.

 

[djp2010]

Re: 30HP johnson hard warm start

I forgot to tell you it just has a primer and no choke-the throttle plate is about 95% closed

 

[ondarvr]

Re: 30HP johnson hard warm start

On a 2 stroke needing to have the throttle wide open for it to start means its most likely flooded. You may have a leaky float needle. The carbs are very easy and cheap to rebuild, so give that a try.

 

[djp2010]

Re: 30HP johnson hard warm start

Thanks for the advice, I have rebuilt the carb-new float,needle and seat,cleaned it out etc. I was wondering if the temp switch (located in the head by the t-stat) would have anything to do with it.The wire coming out of it is a little frayed. What is its purpose and would it maybe be reading a high temp not allowing it to start?

 

[ondarvr]

Re: 30HP johnson hard warm start

If its a brown wire its for the overheat warning system, If it touches the block it will ground the system and the warning buzzer should sound, it shouldn't shut it down though.

Since you said it has spark, It still looks like a carb (fuel) issue.

 

[jtexas]

Re: 30HP johnson hard warm start

Whats your compression?

Hard warm start, 9 times out of 10 is slightly leaky float valve. that or leaky enrichener valve. backfire through the carb confirms rich mixture (too much fuel not enough air). dry spark plugs, now that's contradictory, but who knows?

I'd recheck the float height.
Any chance you might've forgot to replace that o-ring under the valve seat?

The throttle valve should be 100% closed at idle. If idle speed is set too low, it'll be harder to start with no throttle. Idle speed has to be set in the water in gear.

[unrelated to your present question but I recommend test your overtemp circuit; ground the temp switch connector (keyswitch "on"), steady tone should sound; and obviously deal with the frayed wiring. Be a shame to let a little thing like that cause a burnt up powerhead. Myself, I'd probably tape it up but it's probably irresponsible for me to recommend anything other than replacement.]

 

[djp2010]

Re: 30HP johnson hard warm start

Thanks for the advice guys,plugs wet,plugs dry that baffels me too. I rememered the o-ring under the seat,but I just put the float in the way it was-I didn, adjust it at all. It was level, should it be adjusted?

 

[jtexas]

Re: 30HP johnson hard warm start

held upside down, the the bottom of the float should hang perfectly parallel with the carb body. to adjust, bend the tang ever so slightly.

I'm wondering about the compression. (compression tester, less than $50, would be a good investment)

Did you say the throttle plate is 10% open at idle? It should not be, although it seems an unlikely cause of such a hard warm start.

 

[djp2010]

Re: 30HP johnson hard warm start

Sounds like I have the float set right, I'll get a compression gauge over the weekend and post my results. I checked the throttle plate again and it seems to be closed all the way-the little flat spot on the bottom threw me off.

 

[djp2010]

Re: 30HP johnson hard warm start

Checked my compression today with the engine cold-one cylinder is 92psi the other is 100 psi. Some people I talked to over the weekend said I should try a hotter plug, but I'm a little leary.

 

[ondarvr]

Re: 30HP johnson hard warm start

A hotter plug won't help any, and may do harm. That is if you currently have the recommended plug in it now.

 

[djp2010]

Re: 30HP johnson hard warm start

I have the recommended plug in it - maybe I'm not getting 100% of the spark when warm - I know I'm getting spark but maybe its is not strong enough.

 

[jasper60103]

Re: 30HP johnson hard warm start

I would try a fresh set of L77JC4 plugs (gap to 0.030) if you haven't done so already. They're cheap anyway. Still the whole wet/dry plug thing is baffling?

 

[jtexas]

Re: 30HP johnson hard warm start

Spark test (not a "spark plug" test): get an inline spark tester (couple bucks at autozone), set the gap for 7/16", clip it to the engine block, attach the plug leads (one at a time) and look for a strong blue spark while cranking. If it can't jump a half-inch gap in the open air without a spark plug, then it's not firing in the hole under heat & compression.

Your compression is borderline. Test again with warm engine.

See the "Engine Decarb" thread over in the "Engine FAQ" section, maybe you can recover some of the lost compression; if not consider pulling the head for inspection.

 

[djp2010]

Re: 30HP johnson hard warm start

Well I put in a fresh set of plugs, still have the problem. Went and bought a spark tester-set a 7/16 gap-spark jumps whether hot or cold. Didn't notice a blue spark-more like a yellow spark.Plan on "decarbing"on Thurs. Wasn't able to check compression when warm. I did notice after it is warmed up it tends to pull over a little harder at times. I have no idea what thats all about. It looks like there is a new head gasket on it-I guess now I no why it was for sale.