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kellcats521 kellcats521 is offline
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Join Date: Feb 2005
Location: Atlanta Metro
Posts: 219

In general, 2 types of enrichment units exist - one where a fuel pressure regulator has a diaphram that is acted upon by manifold pressure in that it retards the flow of fuel back to the tank as manifold pressure increases. In the aftermarket supercharger market this is called an FMU (fuel management unit), and in our cars the WUR does somewhat serve in this capacity - the actual fuel pressure regulator for the CIS system is in the CIS box/fuel head unit, and the WUR acts to further limit fuel return (thereby increasing fuel pressure and therefore increasing the amount of fuel injected at any given metering rod setting) when the manifold vacuum line connected to it is under pressure (boost). This is a totally passive (non - electronic) system, and as I said it is widely used in the aftermarket superchager kits.

The second unit uses a fuel injector (frequency valve) to add fuel either to the manifold directly or to the CIS fuel system by again limiting the fuel return and increasing pressure in the system. This electronic unit would also measure manifold air pressure and use this to prescribe the frequency valve pulse to either add fuel to the intake or slow/stop fuel return flow to increase pressue in the CIS system. This will have some connection to the MAP/boost sending unit (or a stand alone MAP sensor), the frequency valve plumbed either into the intake or in-line after the WUR, and the controller board. It 'appears' as though you have something of this nature, but without seeing all of it in place I can't offer much more than that.

If it is used as such to build pressure in the CIS system by augmenting the WUR operation (limiting fuel return to increase pressure) and the frequency valve is not opening correctly it could cause a 'super-rich' condition under even slight boost that would result in the symptoms you've described. Again, this is only speculation based on what you've shown/described, and I don't want to be part of you leaning out your mixture and killing a motor when this is removed/disconnected. I would tread very carefully if you remove parts.....

Pat Kelley

Last edited by kellcats521; 04-17-2007 at 08:21 AM..
Old 04-17-2007, 08:19 AM
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