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| Things are tight in the engine room! |
With the radiator leaks and starter problems behind us, I thought we would be doing shake-down drives by now. But The Alfatross’ engine suddenly became difficult to start and maintain idle leading to the suspicion that there must be a problem with the fuel supply system.
It has two fuel pumps. One is electrical mounted under the chassis near the fuel tank. The other is mechanical and mounted on the block.
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| The shielded electric fuel pump |
I assumed having two pumps was normal for 1900s until conferring with Dan Allen. He pointed out that although both pumps appear in the Alfa factory parts manual for 1900s, it does not mean the cars had both types of pumps--only that they had one or the other. So this is another anomaly in The Alfatross' DNA, like the presence of two coils, the floor mounted shifter, the Jaeger chronometer, the strange brake reservoir, and the air horn. Had it been prepared for racing at some point?
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| That can't be right! |
I traced the fuel path from the tank through the fuel filter and electric fuel pump on to the mechanical fuel pump and all the way to the twin Solex 40P II carburetors. Everything seemed to be shipshape at first, but after removing various bits and pieces in the engine bay to expose the mechanical pump I found the proverbial "smoking gun", a shiny steel pin protruding grotesquely from the pump’s back side.
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| Although this diagram is not quite right, the axle pin is no. 5. Pump arm is no. 2 |
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| The pump showing the-arm-to diaphragm linkage. |
Looking at the exploded diagram of the mechanical pump it
was apparent that the pin is the axle for the long pump arm that engages with a cam on the cam chain drive gear inside the block to create pressure by working the
pump's diaphragm up and down. I saw no sign of any mechanism to hold the pin in place.
It had simply worked its way almost completely out of the pump body over time,
rendering the pump inoperable. I could see no way to fix it without taking the pump off because the pin had to be realigned with the arm, its connecting plates, and the two sides
of the pump body.
It turned out to be one of those jobs where the actual repair took less than one minute and no new parts were needed. A dab of JB Weld over each end of the pin on the outside of the pump will prevent it from working loose again.
This reminded me of the kinds of simple things that make restorations expensive and lengthy. It's not the parts but the labor. Removing the air cleaner, hoses, and horns just to gain access, to the afflicted part, then removing the old gasket material, making new gaskets, and putting it all back together again took the better part of a day.
But that's one day closer to completion!
