Would the DeLorean have ran completely out of fuel?

This is more of a.... "mechanical" discussion than anything else but it concerns a Sci-Fi inspired movie so...

Anyway, I'm not sure what made me think of this but it's a long drive home from work and it just sort of came to me as the Back to the Future theme started playing over my car stereo (streamed from my phone.)

Let's set the stage!

Back to the Future: Part 3

Marty has traveled back in time in a repaired DeLorean with the hopes of saving Doc from being killed by contemporary Biff Tannen and bringing him back to the future of 1985. Upon arrival in 1885 Marty encounters a band of Native Americans on horseback fleeing the Calvary, he turns the DeLorean around and begins driving away from them along the rough terrain eventually going down a smallish hill and backing the car into a small cave.

He exits the cave and smells the fuel of the car leaking out from an area in the undercarriage, he's scared out of the cave by a bear, falls down a hill, and knocks himself out and doesn't wake up for several hours. (So no opportunity to go to the car to attempt to patch the hole somehow or at least find a way to collect some fuel.) This leads to one of the obstacles in the movie, he and Doc have to find a way to power the DeLorean in order to be able to drive it back to the future since sufficient fuel isn't available. (They attempt to use spirituous beverages which end up blowing out an engine component, and any fuel that'd be around in 1885 would be unavailable to them in the small town of Hill Valley (gasoline did exist in this time as did internal combustion engines), there's also something of a time crunch having to do with Buford Tannen.)

But I was thinking about it... Would the DeLorean really have completely drained of fuel?

(Let's get one tangent out of the way, they could not go to the DeLorean Doc had come to 1885 in himself and take fuel from it. Storing a vehicle for even as short as a few months requires you to drain it of fuel since as the fuel ages it becomes a thick varnish that'd clog all of the engine and fuel line components. Any fuel in it Doc would have drained before storing the DeLorean and used up in any experiments if he didn't just completely dispose of it to prevent contaminating the timeline with it. Or, in the story-telling context, tampering with the stored DeLorean risks damaging it further making it unavailable to Doc and Marty in 1955.)

Let's allow a couple of things.... I'm not entirely sure any of the driving Marty did with the car over the rough terrain would have damaged the fuel line enough for it to leak, nor do I think where we see the fuel coming from is where it'd even be on the actual car. Even on a DeLorean I'd think the fuel line would be heartier and located somewhere higher up and not directly under the driver's door on the chassis.

So anyway:

The thoughts I have are:

That there's a fuel-pump between the tank and the engine and usually this pump is in the fuel tank itself and at the top of it even, so it seems to me that this alone would be the fuel is fine because it can't flow UP through the pump and then through the lines.

What's pushing the fuel through the lines and out the hole? Before leaving 1955 Doc says there's "gas in the tank" and let's assume he filled it up to give Marty and "himself" plenty of opportunity to use the DeLorean as needed to get back home. So this means the tank is filled with gas and then there's a little bit of air between the top of the tank and the filler door. A hole is formed in the fuel lines. That little bit of air is going to try and push the gas out but... What's going in the new void? Seems to me this would create something of a vacuum that would prevent the fuel from flowing out. I tried a small experiment where I took a full water bottle, opened it, took a small sip, and closed it. Full bottle, small bit of air at the top. Poked a hole near the bottom of the bottle.

The water sort of trickles out... Kind of. Granted it's not a hole-hole I just cut the side of the bottle with the knife to simulate maybe a torn fuel line. Now, I open the cap of the bottle and water flows out, atmospheric pressure pushes it out. Put the cap on, water trickles again. Nothing to fill the void. (Of course this means that when a car is running it has to work against creating a vacuum to get the fuel, but the pump is likely injecting air as it pulls the gasoline though the lines. No operating pump, nothing to push air in.)

The fuel line isn't at the exact bottom of the tank. There's something of a "water line" there and even when the tank is "empty" there's likely something still there that could be gotten to the pump if the car was at the right angle. They only need enough fuel to get the car up to 88, once.

A DeLorean got 18-20 miles to the gallon and had a 0-60 time of around 9 seconds. and 1/4 mile in 14 seconds. So even if they had a 10th of a gallon, like 12 ounces, the car could travel somewhere around 2 miles they only need to travel just over a third of a mile to get to 88. There wasn't 12 ounces of gasoline at the bottom of the tank, in the rest of the lines and even sitting in the engine/injectors (the DeLorean had a mechanical fuel injection, I don't know if that makes it more or less likely for there to be fuel just sitting in the injectors or a nearby reservoir)? Certainly if Doc can build a refrigerator in his lab/barn he could've made a tiny fuel tank to hold the few ounces of remaining fuel they had, calculated an efficient way to accelerate the car and gotten them home.

I dunno, just rambling. Thoughts?

 

“You mean this sucker is NUCLEAR?!”

“No no no, this sucker is ELECTRICAL. But it take a nuclear reaction to generate the 1.21 gigawatts needed for...”

Mark

 

Depends on where the hole in the gas tank is at.

 

I think you might overanalyze a plot point just a little tiny bit. XD

 

"When this baby hits 88 miles per hour... you're gonna see some serious shit."

 

Oh, I know. It's just something that struck me and my mind went wild.

 

"Mr. Fusion powers the time circuits and the flux capacitor, the internal combustion engine runs on ordinary gasoline, it always has."

 

Ahhh, that's why I love BTTF3, they stripped it down and made the story really low-tech and appropriate for being stuck in the old west.

And it was cute to see Doc make a special lady friend.

 

But, the DeLorean always had run on gasoline. Otherwise, how would Marty have been driving it in 1955? The nuclear reactor in it (both the fusion and fission ones) were just to power the time-machine components.

 

I meant the main story line in BTTF3 focused on getting the DeLorean up to 88MPH on rails instead of going on a crazy time-traveling scavenger hunt to get the sports almanac back in BTTF2.

While I love BTTF2, it (understandably) confused the shit out of some people, especially those who may only bother to watch it once.

 

Maybe it could use both to run the car? The first hybrid.

 

Still think the easiest/best way to fix this was to just go back to the 'stored' DeLorean and just leave 1955 Doc and Marty a note. "Hey, a spare jug of gas and some tubing would be super helpful if you wouldn't mind tossing some in the trunk before you come back. No reason why.. Thanks, 1885 Marty"

They could have sent themselves another note the old fashioned way, and then 1955 Marty would have found it with the stored DeLorean, brought extra, and had it. Slightly more of a Bill and Ted style fix than BTTF, but even BTTF did show timelines overwriting each other, so it should have resulted in a tank of gas just sorta appearing in the trunk rather than parallel universe hijinks...

 

No, too risky. You know how Doc feels about paradoxes.

Marty first says it was the fuel line, but later when he tells Doc he says that he tore a hole in the gas tank. If the latter is true and the hole was on the bottom, boom. Fuel gone.

 

that was proof that the DeLorean already had a heavily modified engine and drivetrain. DeLoreans couldn't actually go 88 mph

 

I guess that's why he said it was electric in the first movie, and then it switched to internal combustion for the third film - easier to relate to than saying it was a hybrid (was that even a conceptual thing in 1990?) or otherwise having to figure out how to recharge batteries in 1885.

Or, all the futzing with time in BTTF2 (one of the finest movies ever made) changed how Doc made the machine in the first place. Timey wimey and all that.

Mark

 

No, the electrical part is the whole deal with the time circuits and the flux capacitor. The car always ran on gasoline.

"Are you saying this sucker is nuclear?"
"No, this sucker's electrical, but I need a nuclear reaction to generate the 1.21 gigawatts of electricity I need..."

They don't need 1.21 gigawats to drive the car around a parking lot, Doc is speaking about the mechanics of time travel.

 

Or the plot hole

Welcome to TrekBBS where minutiae is overanalyzed infinitum.

 

The car always ran purely on gasoline, the nuclear generator powered the time machine components. This is abundantly clear in the operation of it in the entire first movie. If the car itself was dependent on the nuclear components then how could Marty drive the car at all to get to the lightning bolt?

Based on where the leak was, it was obviously a fuel line. The fuel tank was a massive thing under the "trunk"/"frunk" of the car. Marty says the thing about a hole in the "gas tank" when they're in his shop but at this point Marty's never been back to the car and likely just misspoke in explaining what happened with the car.

Top-speed of a DeLorean was 110 mph, the speedometer however due to federal laws at the time could only go up to 85.

Nothing ever "switched." The car always ran on gasoline, it apparently had a mechanical issue that caused it to stall or not start sometimes but, well, DeLoreans weren't very reliable. But the vehicle itself always ran on gasoline, how else would Marty have been able to operate it at the end of the first movie?

The time machine components, however, were "electrical" and a nuclear reaction was needed to generate the huge level of electricity it needed to complete a pass through time. The time machine was completely and entirely separate from the car's components. The two just happened to be connected to one another.

The actual speed of the car actually didn't matter either, there was nothing special or magical about 88 miles an hour. It wasn't like that was the "speed of time" or something. It's the speed Doc had calculated the car would be going when the nuclear reactor had sufficiently charged the time circuits and other components to complete a trip through time. Hell, in Temporal Experiment #1 the car traveling through the parking lot wouldn't have been moving at 88 miles an hour based on the way Doc carries out the test. So it was more to do with just how much time the nuclear reactor had had to charge everything up.

Think about it, sit in a parking lot with your foot on the brake and floor the gas, your car (if you really great brakes) will stay still and your engine will rev high, if your car has good torque you might get the wheels to spin. Your tach will show high speeds but your speedo will stay at 0. Why? Because you're not moving!

Doc revs the DeLorean sitting still up to like 50/60 something miles an hour before releasing the brake and letting the car move forward. How fast would the car be moving when he releases the brake? It's starting from 0, not 50/60.

It's possible the test Doc had set-up here simulated the car moving all of the time he just didn't have enough space or range on the remote to do a full acceleration so the remote's speedometer simply showed the speed the car would be traveling at were it always moving. So the first movie suggests the time jump is more just about the engine running at high speeds.

But the second and third movies confuse this a bit more by adding in the flying element and then not having the engine at all, but in the latter case maybe this suggests that something in the car's drive train needs to be moving at high speeds to initiate the time-jump even if the engine isn't actually on.... And this component is used even when the car is flying.

Then there's Doc's jump to 1885 where the car is struck by lightning while largely "motionless" hovering in the sky and goes back. I know they try and explain that the car went into something of a spin/loop from the lightning impact (hence the "99" fire trails when it vanishes) but the car didn't instantaneously start moving at 88 miles an hour when hit by the lightning bolt so, again, it must have just gotten some drivetrain component to move at the right speeds "like" it was going 88.

.... I've gone cross-eyed.

 

Lighten up Francis. We were having some fun. You remember fun, don't you?