Date: Tue, 22 Jun 2004 09:34:45 +0100
From: Grunff <>
Subject: Re: Ancient saab 900 86' carburator failure?

BW wrote: > I'm helping my friend with his ancient saab 900 86' which has a > carburator. It died suddenly on the road and won't start again, but the > plugs spark ok, gas is pumped into the cylinders (you can smell it in > the exhaust and it left some puddles in the intake manifold when we > disconnected the carburator. > > Unfortunately, the screws needed to be unscrewed to check the membrane > are not moving and need some love and care to get open again. I wanted > to check first if indeed this could be the case of a ruptured membrane > or somethinge else internal to the carburator, or if there is anything > more external we can check before trying to get it apart (or simply > changed at the junkyard). > > There is an actuator just next to the intake into the carburator, with > a small hose-fitting on the pipe it actuates, without a hose on it.. > what should connect there ? :) > > Also, the big metal cylinder inside the carburator, visible from the > intake side, is barely moving during cranking. How much should this > open up the intake during cranking, if everything is ok ? If it does > not open up, is it a clear sign of a ruptured membrane or could another > hose be missing somewhere ? The piston won't move all that much during cranking. If you crank with the throttle fully open, it should move a few mm max. I'm not sure it's the carb. A torn membrane is common, but that would result in no/very little fuel in the manifold. But you say you can see puddles of it. You also say you're smelling it in the exhaust. If you have fuel going in, and a good spark, it should at least fire - even if the mixture is way off. Does it? As for the actuator, I'm not sure what you mean. Could you take a pic? -- Grunff

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