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1986 Chris Craft Scorpion 187

H

homerl

Regular Contributor
Gentlemen I could sure use some advice, replaced the filler hose,changed oil,added gas line antifreeze,went to start the motor and it ran fine with water muffs and ran well for a good 5-10min.
Stalled,checked filter/ seperator,emptied two or three times,checked filter at carb cleaned and lots of fuel there.
My question is I do not hear any spray of gas now when I put in full speed. If I put a bit of gas in the two barrel carb it will run for a few seconds.
It's a 305ci 86 motor.Tapped lightly on the fuel bowl but no change.I can't understand why it would run for a decent time and than stop. Is there a accelerator pump or something that feeds gas in after idle? Thanks for any help.:(
 
Ayuh,... Sounds like the carb needs to be torn down, 'n rebuilt, rather than tapped upon....
 
Your vent clear: Below is pasted from another website here i am the author.

You need a hour or less to go thru the gas system. Start at the carb remove the fitting that enters the cab and there is a filter in there clean it.

Now crank the motor with the end of the line in a soda bottle and see if you got fuel being pumped to the carb.

What i do i clean that filter i then clean the one in my pump and then i crank the bow up and i stick a clear hose into the back corner of my tank connected to a dc pump and pump. I pump about 10 ounces of gas with junk and gunk and water till i see clear fuel coming into the bottle and stop the pump.

I blow thru the ant-syphin valve it is the 90 degree fitting that you got to unscrew on top of your tank. The fuel line to the pump is what you follow to the tank, there will be a fuel pickup tube that comes up also.

There may be a screen on the bottom of the tube clean that.

Now your good to go.

With fresh gas every year and the hour spent before you start it up will pay off in the long run.
 
Ok ,installed a rebuilt carb and gas is being sprayed in when you move the throttle handle down now. I seem to be getting a lot of trying to start but a lot of flame backfiring out of the carb. Looking for a couple more ideas as I believe she's close to starting..Checked all screens as advised all were clean,and removed the hose to carb and pumped a fair bit of gas in to a pail,a lot of flow to the carb.Thanks for any further help.
 
So now you know your getting fuel. It either has to be bad gas, electrical problem, or timing issue. How old is your gas? Make sure you are getting a spark at your plugs. I would pull all the plugs out and inspect them too.
 
Ran perfect last october when I stored it,Found out the fuel fill hose was split at the tank so I figure I had about $30 of gas plus a bottle of fuel stabilizer in the bottom of my boat.
I can add gas to the carb and it wants to run so I'm thinking it's the fiel in my tank. I've added 3 bottles of gas line antifreeze and a small bottle of octane booster to the gas.
Have emptied the fuel filter several times in hoping to get to the treated gas.Now when the backfiring is now starting I think I'll use your advice and check the plugs. How long does it take for gas line antifreeze to work? . Thanks
 
The answer here is to lift the boat trailer as high as possible or park it on a hill.
Remove the gas tank sending unit and PUMP/ DRAIN all the gas out of the tank

that is if the gas is contaminated. Really no other way to be sure.
 
Thanks kghost,but is it somewhat normal after a motor backfires it goes backwards for a half turn or so? Thanks
 
Was just talking to a friend of mine who works on boats, he thinks this backfiring and backwards turn of the motor that may be the timing is off.
I took the fuel filter off ,drained the old gas, filled it up with fresh gas with the same backfiring results.
Is it possible to have the timing change after the boat first ran well a week ago for the best part of ten minutes than stalled?
I still feel I'm close to cracking this problem.thanks .
The boat is still dry docked in my backyard,not like I was on the lake and letting her go.
 
Changed gas,I can see gas entering the carb when you move it forward. Idles well, soon as you give it the fuel it wants to miss and back fire,than stall. I should say half of the gas is new but that backfire upon acceleration could it still be gas related?. Nothing was changed since it was stored and ran well last season. Sorry, I did put a rebuilt carb on, better but not still solving my problem. Thank you all,homerl.
 
For the last 45min,the boat idles at 650 rpm smooth without a shake.Put it into gear still idles until you throttle it and it revs up and dies. I do have a spare coil and a thunderbolt lV ignition. It seems that maybe the timing advance is not working?,or am I on the wrong track? thanks.
 
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