[Roadsters] 44PHH2 Type Q fuel leak

[Eric G]

Overflow from the old-style carbs can often be traced to a too-high fuel 
level caused by a needle not sealing properly.  There have been some 
rather ordinary replacement needle/seat sets around that don't have the 
spring-loaded needle stem.  These don't seem to have much of a life - 
hope you don't have them.  If you have a replacement needle and seat, 
I'd give that a try, or, swap them between the carbs to find out if the 
problem shifts too.  Sometimes the smallest piece of crud that's almost 
invisible can cause poor sealing and then overflow and it can be a bit 
difficult to dislodge the culprit.  Compressed air can work but not 
always - a clear insect wing part about 1mm square gave me the same 
symptoms.  No idea how it got past the filters or how long it had been 
in the system before causing a problem.
If you take off the jet cover, you can check the fuel level - it is 
meant to be 20mm above the centre of the main bore when the fuel 
pressure is about 3.5 psi.  As long as it's not above the top of the 
venturi, it's probably pretty close.  Adjustment is by selecting seat 
washers of appropriate thickness.  My guess - the needle is the problem.

(There is another source of rich running caused by a repairable issue in 
the internal start circuit of the old-style carbs, but that doesn't 
result in overflow)

Regards,
Eric in Townsville

On 7/07/2010 2:15 AM, RWM wrote:
> From out of the blue I am experiencing fuel system issues.  Car had 
> not been run since last Fall, first wouldn't start (lack of fuel, 
> traced as noted below), ran well for a couple of laps around town, 
> then picked up a stumble and a carb/fuel leak from one of the old 
> style 44PHH2 Type Q Mikunis.
>
> Remaining issue is a cylinder out/slow throttle response while 
> running, accompanied by a significant raw fuel leak out of the #4 
> (rear-most rear) carb throat after shutdown and most likely the cause 
> of the cylinder-out while running condition.  Stuck float valve or 
> sunk float, perhaps?  (For insurance, I run one in-line filter before 
> the fuel pump, two in-line filters after the pump, plus the banjo 
> fitting mesh screen, so I wonder what it could be that got by all that 
> filtration.)
>
> Also, is anyone seeing the "new gas" (high alcohol content) causing 
> rapid deterioration in fuel system gaskets?   Had to rebuild the fuel 
> pump due to a piece of debris (looked like solid varnish) stuck in a 
> body valve.  In the process, went from no fuel delivery to the fuel 
> leak noted above.
>
> TIA for suggestions/recommendations.
>
> - Bob Mann, '68 2000 Solex ________________________________________
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