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#Post#: 57564--------------------------------------------------
Revs limited
DIR By: dra890
Date: April 16, 2013, 2:15 pm
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I wonder if anyone can help me.
I have a series 3 2.25 petrol with an SU hif44 carburettor that
was left undriven for a year. Upon starting to drive it again I
found that the revs seem to be limited. At first I couldn't get
above about 30mph in third gear and low forties in fourth -
about 2500rpm on my landrover (32 inch tyres).
After seeing fuel coming out of the overflow I thought 'Aha,
sticking float' so I emptied the carburettor's float bowl and
sprayed carb cleaner in through the fuel inlet pipe until it
came out of the overflow, then again with my finger blocking the
over flow so it came out of the jet. I then ran the engine and
found it much better.
The engine will now run to around 40mph in third , but this is
still only around 3500rpm. There should be around another
thousand rpm available. It pulls strongly up to 40mph but then
refuses to pull any higher, almost like it has a rev limiter.
What could this be?
It is not the ignition. I've tried individually changing the
coil and distributor for correctly set known good ones, and
different spark plugs have been tried. Pulling the king
lead/individual plug leads I can get strong sparks to the block.
I've since stripped and cleaned the top of the carburettor. I
removed the dash pot and cleaned inside with a soft cloth and
petrol, the same for the piston, and carefully wiped and
inspected the needle without damaging it. None of these were
dirty or in bad condition. I also sprayed carb cleaner down the
jet with a straw attachment, and spraying into the float bowl
through the fuel inlet with the overflow blocked it came out of
the jet strong enough to miss the engine and wing and nearly hit
the next car over. I then correctly reassembled the carburettor
and refilled the damper, but this has made no difference. The
piston opens fully when revved.
I've also tried looking for vaccuum leaks but found none. All
the hoses are attached correctly and the engine has good vaccuum
- over 22 inches at idle.
It never used to do this. Does anyone have any ideas?
#Post#: 57579--------------------------------------------------
Re: Revs limited
DIR By: goinnowherefast
Date: April 16, 2013, 2:53 pm
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Is it running on all cylinders?
is the fuel good?
#Post#: 57580--------------------------------------------------
Re: Revs limited
DIR By: Albert Ross
Date: April 16, 2013, 2:55 pm
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Not really, no....
But this part of the forum is a good place to start.
HTML http://ollr.createaforum.com/general-discussion/
#Post#: 57615--------------------------------------------------
Re: Revs limited
DIR By: dra890
Date: April 16, 2013, 4:00 pm
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Oops, sorry. Didn't realise it had been so long since I last
posted. Intro now done.
It runs on all cylinders, and the fuel is good (refilled several
times). When it reaches it's 'limit' it just acts as though I've
taken my foot off the accelerator.
#Post#: 57616--------------------------------------------------
Re: Revs limited
DIR By: parksy64
Date: April 16, 2013, 4:07 pm
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What air filter you using with the SU? Pancake K&N? :-?
Have you tried running it without to see if it is an air
restriction?
Too much fuel not enough air- hence overflow? or go down the
other route of not enough fuel and look at the fuel pump, fuel
pick up and fuel filter....
#Post#: 57631--------------------------------------------------
Re: Revs limited
DIR By: NoelC
Date: April 16, 2013, 4:44 pm
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--- Quote from: dra890 link ---
>
> Does anyone have any ideas?
--- End Quote ---
I had a similar thing with the HS6 on the 88. Looking at the
diagram below...
HTML http://www.scparts.co.uk/clickable/gross/Bilder/2587.gif
...does the lower part marked 3 (piston) move freely up and down
in the upper part marked 3 (suction chamber)? This was the issue
with mine not revving, a quick clean up with carb cleaner and
wipe with WD40 sorted it.
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