Join Date: Jan 2003
Location: Rapid City SD, Black Hills of South Dakota, Queens NY
First of all, I've never even seen a Montreal in person, so I have no direct experience on the Alfa V8. The SPICA system, is functionally the same as the 4 cylinder models, so I'll take a stab at it.
Has it ever run well while you've owned it, or did you buy it broken?
I'm going to assume you're correct and that the ignition system is good. Also, has this car sat unused for a long period of time before this problem occurred?
The SPICA pump operates at about 350-400 psi, so something would have to be broken in the pump section of the injection pump for a particular cylinder not to get fuel in the fuel pipe.
Let's check the easy, non-invasive stuff first:
1. Are the fuel pipes in good condition and have not been kinked? Be carefull with those pipes. Don't bend them. There are no spares available except from salvage, and for Montreals, that means virtually nil available.
2. Disconnect the fuel pipe at the injector and crank the engine without starting it for about 15 seconds. (Disconnect coil wire) Any fuel at all coming out the fuel pipe? It won't be much since there's very little injected in each cycle. If no fuel at all, loosen the connection at the injection pump and see if there's any exiting the fuel tower on top the pump.
If really getting no fuel (compare to a good cylinder), then I might suspect that the plunger pinon has loosened and is not turning the plunger, thus allowing the variable displacement port to go to the fuel delivery mode. This sounds complicated but is really simple when you look at it. See the picture below. The toothed rack at the back moves forward and backwards (full forward being fuel cutoff). The pinons have a few teeth also and are turned slightly by the rack (which is connected to the throttle). These pinions pinch the plunger and thus turn the plunger to increased fuel delivery.
So to make a long story short, if the pinch screws are no longer pinching the plunger, then throttle movements aren't going to increase fuel delivery in those particular cylinder(s) affected.
I'm not saying that's what's wrong, but apart from a blocked fuel pipe, that's about the only thing that can affect fuel delivery in just a particular cylinder.
I suppose, but very very unlikely, there could be a fuel blockage in the injection pump internal fuel manifold in those particular cylinders.
If you think the pinions may be loose (again, very unlikely), you can remove the inspection plates on the side of the pump, cycle the throttle and look for the plunder shafts to move with the pinions and toothed rack. If they don't, then the pump needs to be sent back to Wes Ingram for a re-calibration. It is completely impossible to reset the pinions without a dedicated test bench and the knowledge on how to do it.
The picture below give you an idea of what I'm talking about. Note that this is a 4c pump, but the Montreal pump is functionally the same.