PHF32 Accelerator pump No Pump...

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Joined: Sat Sep 05, 2020 3:57 am

PHF32 Accelerator pump No Pump...

Post by Tinkerbell »

Hi All,
I have rebuilt the PHF32s with new acc. diaphragms. And I don't see any fuel squirt. Somebody said to put your finger over the check valve at the top of the acc. pump, but I do not see any connection to atmosphere in my check valves --there is a brass plug in the center.
Questions: 1) Should you be able to check the check valve function by blowing by mouth? I can't seem to blow in or out of the internal (small) end of
the valve.
2) Does the pump sometimes need to be primed?
3) Somebody said that the jet and the jet holder at the side of the bore had to be critically aligned such that the slots in the jet aligned
with the jet holder when screwed in tight. This makes no sense.
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750 GT
Posts: 168
Joined: Tue May 31, 2016 3:49 pm

Re: PHF32 Accelerator pump No Pump...

Post by 81mhr900ss »

Hi Kara: I rebuilt my PHM40s last year. The only thing I did not touch was the factory accelerator pump screw settings; the screws have a dot of red paint on them and all they do is limit the travel of the pump diaphragm. Screw in to reduce and screw out to increase gas flow through the pump so if screwed in too far, it's feasible that the pump will not pump.

Check-valve: It's the tiniest jet and I do recall trying to blow through it but don't remember feeling the flow. Maybe you could try blowing through it into water and look for bubbles?
Priming: I did not need to do anything special to prime the pumps; from a completely empty float bowl, all I needed to do was open the fuel valves, twist the throttle several times and the pumps started squirting.
Pump jet: What I think the third item refers to is the pump jet. It has a flat side that engages with a flat in the hole in the carb body so that the jet hole points in the right direction; it can't be put in wrong.

I have a bunch of Dellorto manuals. If you'd like copies, send me your email address: [email protected]
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Craig in France
Paso 750
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Joined: Tue Mar 23, 2004 3:58 pm
Location: Montpellier, France

Re: PHF32 Accelerator pump No Pump...

Post by Craig in France »

Hi Kara,

More than you'll ever want to know in the two docs attached :-D .

Priming, bleeding the accelerator pump-page-001.jpg
Priming, bleeding the accelerator pump-page-002-3.jpg
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