motor dies without choke?

[gussbuster]

I recently rebuilt my carbs on my 150hp and now when I start it, A: it will only start when choke, and B: I have to hold the choke in to keep it running or it dies within about 10 seconds. Am I too rich, too lean? Is there something else I should be looking for? All carbs were set at a base setting of one turn on the idle mixture screw. I just dont know where to start. Does anyone have good experience getting these engines tuned properly?

thanks guys!!

 

[pnwboat]

Re: motor dies without choke?

Sounds like it's too lean. If everything is operating correctly, 1 tun out from lightly seated, motor should run, but you might try 1 1/2 turn just to see. If still having problems, then I'd look a the fuel pumps, then carburetors.

Why did you rebuild the carbs in the first place?

 

[gussbuster]

Re: motor dies without choke?

the motor is new to me and it had some dirty gas in it. Everything was gunked up and one of the carbs leaked. Fuel pumps are new....I guess ill have to try one and a half turns.

 

[gussbuster]

Re: motor dies without choke?

one other observation I had....my idle speed adjustment is adjusted to the max and I still have very low idle speed...again this boat/motor are new to me. Is it possible that my timing is off? If so, how can I check it in the driveway?

 

[pnwboat]

Re: motor dies without choke?

You may have to do a "Link and Sync". Service manual explains this, but basically what you're try to achieve is to make sure the throttle plates in all 3 carbs are opening exactly the same. It's really critical at idle. The throttle plates should all have the exact same gap between the edge of the throttle plate and side of the carburetor throat.

 

[jason32038]

Re: motor dies without choke?

Sounds like you need to adjust your mixture screws. If too rich the idle will be low and rough. Too lean idle will be higher and possibly cough or sneeze like a mini backfire.

 

[rickryder]

Re: motor dies without choke?

Just my 2 cents pilot jets clogged? That will affect the base idle.

 

[gussbuster]

Re: motor dies without choke?

Im gonna run through everything this weekend....check timing and spark. Re-link and sync carbs...try 1-1/2 turns on idle mix screws. Ill also back out the idle speed screw (it is set all the way in right now and still getting low idle) then re-adjust the carb linkage. I will let you know how I make out.

Thanks again for all of your help! Any other ideas will be gladly taken! Just want it running perrrrrrrrfect!

 

[jerryjerry05]

Re: motor dies without choke?

If the pumps are new and put together right and the hoses and squeezie are ok. Then check the float level and then like RickR said check the main jet as it also has the slow speed jet in there.J

 

[gussbuster]

Re: motor dies without choke?

Ok so I did everything today...checked/adjusted timing ( it was a little bit off ), re linked carbs....set Idle mixture and ran it. It did run a little better but still needs adjustment.

Then the scariest damn thing happend to me...while running it, my flushing ears fell off (obviously I didnt know it) I had it running at high idle as I was messing with the mixture screws......then the overheat buzzer starts going off (thank god it works!!) I looked down to see my flusher on the ground and promply went to turn off the motor.....IT DIDNT TURN OFF!!! Apparently it got so hot that it was running on its own, without spark...I didnt know what to do....not only was it running with no water...it reved up higher than I was able to get it when I was running it... I franticly rushed around tring to get it to turn off...took the key out...still running. I crapping myself thinking this thing is gonna blow any second...I finally went back to the motor and opend the carbs all the was up and it flooded itself to a stop.

Needless to say my water pump was fried. I dont know if anyone else has ever heard of this happening but it was damn scary. I had a spare impeller (always keep a spare) and replaced it...so we will have to see what happens in the morning...fingers crossed, no real damage was done. Ill keep you posted!

 

[Rscardina]

Re: motor dies without choke?

Sounds like your choke solenoid is bad or the red lever is going the wrong way..

The choke solenoid feeds gas bypassing the carbs to get your initil start..afetr that the carbs take over..per say..

if it need choke to stay on then carbs are not flowing..or feul pump is whacked..


As far as it running without spark..not possible.. but certainly something to look at electrically as turning the key off should have shut it down

 

[roscoe]

Re: motor dies without choke?

As far as it running without spark..not possible.. but certainly something to look at electrically as turning the key off should have shut it down

Sorry, but it is entirely possible and does happen.
Called a 2 cycle runaway.

Contributing factors:
lean fuel condition
warm engine
hot spots on the head or piston caused by dings or carbon buildup

It will detonate under compression and ignite from the hot spot.

Choking out the carbs, or covering the air intake is the quickest way to kill it, but is often hard to do while you are running away and looking for cover.

 

[gussbuster]

Re: motor dies without choke?

Thanks Roscoe, I know im not crazy! As far as my running problem goes....the only thing I was leary about when rebuilding my carbs is 1: the new floats are now plastic and do no have a float level adjustment tab...it is what it is with the plastic ones. I also replaced the needle inlet valves....my old ones has the red rubber tip...the new ones do not have the rubber tip....could this be a contributing factor?

Its very frustrating

 

[Rscardina]

Re: motor dies without choke?

Sorry, but it is entirely possible and does happen.
Called a 2 cycle runaway.

Contributing factors:
lean fuel condition
warm engine
hot spots on the head or piston caused by dings or carbon buildup

It will detonate under compression and ignite from the hot spot.

Choking out the carbs, or covering the air intake is the quickest way to kill it, but is often hard to do while you are running away and looking for cover.

I never had that experience..but with hot spots as you mention i can see how that could happen. That is a bit scary..