Kevin,
I recently had a similar problem whilst ground running my Subaru. I
suspected the excess fuel being a fault in the diaphragm so switched
Elisions with my spare Subaru engine. Fault cleared so I opened the
diaphragm housing to find a waxy residue causing the ball valve to stick in
the open position, the one the diaphragm drives.You can check for this fault
easily by removing the air filter box and running the pump with the mixture
rich and throttle closed engine stopped . There should be no fuel exiting
the meter needle in the throttle body. Run it and cycle the throttle whilst
an observer looks for any fuel excess. If this is your problem you will see
the fuel squirting out of the throttle body venturi against the incoming air
whilst at idle. Without the air filter housing it may even keep running in
this config but with air filter it will rich cut. If you blow through a
narrow tube into the small hole on the right of the throttle venturi
casting, this will open the diaphragm and allow fuel through without running
the engine. If fuel flows after your stop blowing, then that's your problem
and you will have to open the sealed diaphragm housing voiding the warranty
if it is still valid to fix it here or send it back to Ellison. If you get
it to me I will fix it for you providing the above symptoms agree. Let me
know your findings regardless.
Gary McKirdy
----- Original Message -----
From: "Kevin Taylor" <kevin@eastyorkshire.co.uk>
Subject: Low RPM rough running
> Folks,
>
> I had a intermittent problem today with rough running at low rpm 2500-3000
> rpm on my Subaru. It cleared by leaning the engine then going back to
fully
> rich was then OK again apart from once or twice but generally I was able
to
> replicate it enough times to confirm leaning did solve the problem. The
> first time I noticed it was immediately on start up from cold on the first
> run of the day, it got rough I leaned it then put it back to fully rich
and
> it stopped! I'm thinking along the lines that it may be possibly plug
> fouling or just somehow the slow running jet is too rich? I haven't had
the
> plugs out yet but will next time I'm at the field. I incidentally it does
> run rich and always has done other Subaru owner I have spoken to have
always
> leaned even on the ground, to assist in avoiding fouling.
>
> Its been as sweet as a nut since I got it and I've done 50 hours in the
last
> 3 months and never seen a suggestion of this before. Plugs are only about
> 15-20 hours old.
>
> Any suggestions appreciated (other than put a 912 in which I'm sure some
of
> you are muttering under your breath right now)
>
> Kev T
> ---
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