Good for 27 seconds...please help By harry (Read 668 times)

[harry]

I am trying to get a couple of scooters that sat for 10 years ready to sell for a cousin.  This is a 125cc with 5 miles on it, so I am pretty sure it had fuel in it at one time.   I flushed fresh fuel through the lines.  It wouldn't start, so I removed and cleaned the carb.  The idle mixture was originally about 1.5 turns open.  The enrichment solenoid was working when I tested it while cleaning the carb.  I put it back together and it started right up, warmed up normally and I rode it for about 10 miles.  It ran great.  I put about an oz of Gumout Carb Cleaner with a gallon of gas in the tank and let it sit while I worked on the 2nd scooter.  Since then I have not been able to get it to warm up.  It starts immediately and runs smooth for about 25 seconds and then starts to slow down and die.  It may restart at that point for 5 seconds and then dies again.  If it sits for a while, it will start back up fine for another 25 seconds...

There is fuel in the filter.  I have tried bypassing the vacuum petcock, removing the tank cap, all with the same results.  Fuel flows out of the line when I crank the engine so I think the petcock is fine.  I drained the Gumout fuel and replaced with fresh 93 octane to see if that would help. 

What am I missing??

[trashtruck12172]

sounds like the jets may be partially clogged.

[cyborg]

Coil could be on the way out,,,,,next time it dies give the coil a decent rap with either a hard rubber/ wooden mallet see if it will lite up right away,,,but it does sound like that's the problem

[harry]

Jun 18, 2016 21:17:51 GMT -6 cyborg said:

Coil could be on the way out,,,,,next time it dies give the coil a decent rap with either a hard rubber/ wooden mallet see if it will lite up right away,,,but it does sound like that's the problem

Thanks for the suggestion.  I tried a new coil - same result.  Other ideas?

[thecableguy]

Re-clean the carb and replace the fuel filter and all fuel lines. Fuel lines can deteriorate from the inside and the bits of rubber can clog the jets, esp the idle jet.

[jct842]

Gas tank too can be source of "junk" in fuel system.

[harry]

Jun 21, 2016 12:03:10 GMT -6 thecableguy said:

Re-clean the carb and replace the fuel filter and all fuel lines. Fuel lines can deteriorate from the inside and the bits of rubber can clog the jets, esp the idle jet.

I can see how a clogged jet could keep it from starting, or idling smoothly, but it idles fine for about 40 seconds on this last try and then won't keep running on restart until a sufficient rest period.  Perhaps the issue might be more related to float needle or enrichment solenoid?

[harry]

Jun 21, 2016 12:53:29 GMT -6 jct842 said:

Gas tank too can be source of "junk" in fuel system.

Fuel filter is micro-mesh style and was clean - before I cleaned it.

[cyborg]

Run it till it dies and crack open the cap on the fuel tank and tell me air rushes in,,, if it does drill a TINY hole I mean a small hole in cap and go for a ride alright already

[cyborg]

Or crack open the fuel tank cap and leave it loose and start it and watch it idle till the tank runs dry

[thecableguy]

I think he did that Cyborg... Yeah, float needle not opening enough, maybe some crud in there gumming up the works.

[cyborg]

I've also seen fuel hose separate and inside layer fold inward and shut off and /or restrict flow,,,I run clear motocross bike hose now on all my machines,,,one glance is all it takes to confirm flow

[harry]

Jun 21, 2016 17:02:56 GMT -6 cyborg said:

I've also seen fuel hose separate and inside layer fold inward and shut off and /or restrict flow,,,I run clear motocross bike hose now on all my machines,,,one glance is all it takes to confirm flow

Thanks I will check the hoses.  Could the cold enrichment solenoid be a factor?  It seemed to be functional when I tested it, but might be binding on the passageway.

[harry]

Jun 22, 2016 0:33:11 GMT -6 harry said:

Jun 21, 2016 17:02:56 GMT -6 cyborg said:

I've also seen fuel hose separate and inside layer fold inward and shut off and /or restrict flow,,,I run clear motocross bike hose now on all my machines,,,one glance is all it takes to confirm flow

Thanks I will check the hoses.  Could the cold enrichment solenoid be a factor?  It seemed to be functional when I tested it, but might be binding on the passageway.

Ok, new clear fuel lines did not help, gas cap on/off didn't change anything.  So I removed and cleaned the carb again, paying particular attention to the idle mixture passageway and the autochoke passages.  Reassembled with my idle mixture at 2.5 turns open and it won't start.  Removed the breather and shot some ether in and it ran for a couple of seconds, so I still have a fuel problem I presume.  Put my hand over the carb inlet during cranking and it has good vacuum.

I tried the fuel into the intake manifold test and the engine started, so it is a fuel problem of some sort. 

I expected the idle mixture screw to come to a point, but it is tapered to .022" dia at the tip.  I presume that this is normal.

[cyborg]

Float stuck in the closed position ( up),, so no fuel getting to the carb,,, it's obviously a fuel issue now that you got it to pop with ether