I went through a similar experience last year. Two sets of carbs, I thought
they were all bad! You don't say what type of carbs, my experience relates
to HIF's. Anyway, my problem was pretty much the same as yours.
Most probable cause is massive vacuum leaks, as has been mentioned to you. I
had leaks around the intake manifold, between the manifold and carbs also.
Even though I had a new manifold gasket. I had my intake manifold
belt-sanded at the shop to insure a flat mating surface. Use a new gasket,
with a smidge of sealer & properly torque it down.
Start the engine, and while it's running, spray carb cleaner at the junction
of the manifold/engine, base of carbs, etc. Change in engine speed will
indicate the presence of a vacuum leak.
Also, on HIF's, there are two ports on the carb (maybe more?). The vacuum
port, which goes to the distributor, should be plugged, or connected. The
engine *should* run either way, but a leak is not desirable. There is also a
vent port, which goes to the vapor cannistor. Do NOT plug that one, as your
HIF's will flood.
I got TONS of good advice here, you might want to check the archives, as I'm
sure you'll find a lot of relevent info!
Hope that helps
--
-----------------------------------------------------------
Marc Siegel, Charm Net LLC eMail: smarc@abs.net
Baltimore, MD http://www.abs.net voice: 410/361-8160
-----Original Message-----
From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
Behalf Of BarrMark262@aol.com
Sent: Monday, February 09, 2004 9:09 PM
To: mgs@autox.team.net
Subject: What I don't know about carbs.-long, sorry
Please educate me.
I am only able to start the engine on my project 74B with the choke
completely activated. As soon as the choke is pushed in, the engine dies.(
Engine and
carbs rebuilt by the "pros.")
I even installed a second set of carbs that I own, and had the same results.
Either I have neglected to hook up something, or I have 4 bad carbs. Do you
need the carb/dist vac advance line connected? Do some or all of the
emission
lines need connecting? Does the accelerator cable as well as the choke cable
need connecting?
I pour gas into the carbs, even starting fluid, and I still cannot start it
with out the choke handle fully extended.
I was able to static time the engine, I have a good spark, but for some
reason I can't get fuel to keep flowing well enough to keep the engine
running.
When I disconnect the fuel line to check the pump gas flowws beautifully.
Please tell me what to look for next. I have really tapped hard on the carb
floats on all 4 carbs, but it did not seem to help.
Thanks, and sorry again for the length.
Dennis Barr
Medford, Oregon
|