O.T. Gas mileage using cruise control

[Ed Pawlowski]

That would depends on the pump. A mechanical will continue to provide fuel. An electric will not and once the nearby fuel in the line is gone, engine will stop.

[Snag]

Nope . There's the fuel in the carb bowl ... and injectors don't inject when the power is cut no matter how much fuel is in the line .

[Marilyn Manson]

This is not a joke.

I had an 60's era AMC in which the fuel pump was used to moderate the speed of the windshield wipers.

The wipers ran off the engine vacuum. As you accelerate, the engine vacuum drops and the wipers should theoretically slow down or even stop. However, at the same time, the fuel pump is pumping faster because the engine needs more fuel.

So, replace the standard cap on the fuel pump with a vacuum booster pump, tuned to increase the vacuum used by the wipers by the same amount that it drops during acceleration. In general, it works pretty well.

When my booster pump went bad and parts were getting hard to find, I went through a period where I had to by-pass the pump to get the wipers to work. It was always an adventure getting on the highway in a rain storm. If I hit the gas too hard, the wipers would stop, so I had to kind of feather the accelerator on-off-on-off to get a sweep every now and then.

[Ed Pawlowski]

That would depends on the particular engine. Just as your model airplane, disconnect the fuel and it stops. Some of the old Chevys had mechanical fuel injection. I think to about 1965

[Ed Pawlowski]

Vacuum wipers were a genius invention. Wipers would slow or even stop when you needed them most, like passing or up a hill.

I think it was late 50s that some cars finally got electric but they still had vacuum on some 60s.

[Clare Snyder]

In a carbureted engine if the throttle is open fuel is getting to the cyls as long as the engine is turning, and when lean anf hot, you get autoignition. A fully closed throttle can NOT diesel - just like an EFI engine cannot diesel.(except in the case of an early LJet with a dripping cold start injector - and even then everything has to be "just right" for that to happen)

[Clare Snyder]

A carbed engine can diesel for quite some time on the fuel in the float bowl. An example I will NEVER forget was a 1275 stage 3 BMC engine in a Mini Moke running on 78 - 83 octane fuel with 2 DCOE40 webers. Get it up to operating temperature and shut it off at 1/4 throttle and you could drive it 15 to 20 feet into the shop with no spark. You couldn't buy fuel of adequate octane other than AV Gas in Zambia in the early 70s Also a top fuel dragster needs a real good spark to get it lit - but after the first 60 feet (or less) it's auto-ignition all the way to the end

[Marilyn Manson]

AMC had vacuum wipers until at least 71. We used a wire tied to the wipers on my buddy’s 71 Javelin when the vacuum system failed. The wipers would go up but not come down. The passenger would pull them down and let them go back up, then pull them down again.

He couldn’t drive by himself if it was raining.

[Clare Snyder]

You want to see what happens when a supercharger seel goes south on a Jimmy 2 stroke diesel , or you take out a ring land or puncture a piston on any deisel engine (with the possible exception of the off "throttled" late model passenger car engine) Saw one suck in a pair of coveralls thrown into the intake in an attempt to "smother" it - and spit them out the exhaust in bits before the 2x6 was slapped over the intake (6 cyl allis chalmers 918 loader tractor - 301 cu inch (acd2900?)

[Clare Snyder]

As long as they had the double fuel pump -(fuel plus vacuum) and it was functional, the wipers would still work going up hill.

[Marilyn Manson]

There is "functional" and then there is "functioning properly". Any of us that had vacuum wipers (including probably you) know the difference. ;-)