What to do when ran out of fuel?

SoaceMunky

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I've seen a few bits here and there...but nothing concrete.
What do I do if I accidentally run out of fuel?
I've read that I may need to prime the fuel pump? Can someone please set me straight?
 

Audi5000TDI

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1. Put 5 gallons fuel in your tank.

2. Pull your engine cover

3. Look at your injector pump.

4. Find the black fuel return line from your #4 nozzle to your injector pump. This should be located at the highest point on the Injector pump fuel body.

5. Beg, steal, borrow.... or better yet buy a $30.00 vacuum pump with a gauge and a reservoir.

6. Suck the fitting on the injector pump until you get no air bubbles.

7. Reattach the fuel return line hose from nozzle #4

8. Start it up.


It's very destructive to run your fuel tank way down.... you injector pump has to work too hard to draw fuel up the fuel column. Keep at least 1/4 tank in your fuel tank and this wont happen.
 

SoaceMunky

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so its bad to get fuel only when the light is on? ruh-oh... i think ill stick to your advice.
 

cage

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lakewood, ohio
Yeah right! I mean your fuel light comes on WAY before you actually run out yet you ran out and are now claiming that you won't let it run down to the point that the light comes on. Do we look stupid to you?
 

jdboone

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Cage, give him a break -- He didn't say he actually ran out of fuel, he just asked what had to be done if he did.

Think this was good for me to read too. Was going to let my wife commute tomorrow with a quarter tank -- she should make it ok, but its just stupid to take a chance. Heading to the station now....:)

Dan
 

SoaceMunky

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thanks for the info guys. i usually try to drive as far as possible on each tank, but i had no idea this could be detrimental to the fuel pump.
i'll stick with your advice for cheaper fillups. also a good excuse for me to do it more often ;)
 
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mgrusin

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2004 4-door Golf TDI (PD)
Half-tank, huh? I always fill up soon after the fuel light goes on. I estimate that I have at least 2 gallons left = 80 miles. The most I've gone before filling is 60, so it's at least that. I like keeping track of the range I have on a full tank so I can prevent future middle-of-nowhere problems (like the 60 miles I just mentioned).

...And technically, the less weight the car is dragging (like fuel), the better the mileage. This votes in favor of less fuel on board, but that's not a good trade against safety.

-MG
 

TylerSales

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I like Doc's view on the half tank and less $$$ per fillup. Thats my reasoning for early fillups too! And maybe its just my car or something but When I changed to fuel filter I forgot to fill the filter with diesel before starting it back up, and I just cranked the engine over for about 10 seconds and let the starter cool down a bit then did it again. Cycled like that about 3 times and I was running smooth again.
 

Chemboy

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Audi5000TDI said:
It's very destructive to run your fuel tank way down.... you injector pump has to work too hard to draw fuel up the fuel column. Keep at least 1/4 tank in your fuel tank and this wont happen.
Is this really true? I did a search, but came up emtpy.
 

SoaceMunky

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TylerSales said:
I like Doc's view on the half tank and less $$$ per fillup. Thats my reasoning for early fillups too! And maybe its just my car or something but When I changed to fuel filter I forgot to fill the filter with diesel before starting it back up, and I just cranked the engine over for about 10 seconds and let the starter cool down a bit then did it again. Cycled like that about 3 times and I was running smooth again.
i assume the fuel pump is a wet pump, hence the need to prime. but there are two pumps, one is inside the engine? are they both wet pumps? i think this is kind of detrimental to driving, why would they make them like that? maybe it doesent need to be primed? whats the deal?
 

TylerSales

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I'll leave it up to the experts to go into more detail; from what I have done all I had to do was crank the engine over a couple of times and it soon fired up. Ran pretty rough for the first minute or so but then was perfect after that.
 

Audi5000TDI

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Tyler.

There is no telling what kind of damage you did cranking you injection pump dry without fuel.... The rotary head in your injector pump needs the lubrication provided by diesel fuel bathing it. Scoring and gounging can be the result, as well as shortening the life of your injector pump. Diesel parts aren't cheap... Read first or buy a Bentleys service manual so you know what the proper procedure is.

Diesels are completely different animals from gassers, with different lurication needs... kind of like a 2 stroke that needs premix. Diesel fuel has lubricants in it... it's oil, not gas.
 

Audi5000TDI

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Chemboy.... go suck a water column up 10 inches vertical versus 10 feet vertical, plus suck it through a fuel filter that provides resistance. That's what your injector pump has to deal with.

1.5 gallons is bottom of the tank... 10 feet vertical column up vs 15 gallons 10 inches of vertical lift.... Do the math on the fuel column.
 

oldpoopie

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mrGutWrench

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Audi5000TDI said:
(snip) It's very destructive to run your fuel tank way down.... you injector pump has to work too hard to draw fuel up the fuel column. Keep at least 1/4 tank in your fuel tank and this wont happen.
__. If I understand what you're saying, I think that this is wrong. The circulating pump ("pump 1") on the VE engine has to pull fuel through the filter. The amount of lift between full tank and low tank is insignificant in terms of the load on the pump. Of course, the PD with the lift pump is different anyway.

__. And Space, it's not that these pumps need to be primed but if you start them dry, you pump air into the injector lines before "pump 1" can lift and circulate fuel into the high-pressure side of the injector pump. Then, you have "air lock" (as W Dog very accurately describes, above). It's not really a "prime" thing. And, as described, it's really bad for these pumps to be run dry. (Again, PD's are different in detail.)

__. Still, I'd NEVER try to start a car with an empty filter. When I do my filters, I fill the hose from the filter to the pump before I attach it.
'
 

Chemboy

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mrGutWrench said:
__. If I understand what you're saying, I think that this is wrong. The circulating pump ("pump 1") on the VE engine has to pull fuel through the filter. The amount of lift between full tank and low tank is insignificant in terms of the load on the pump.
That's what I was thinking too. These pumps are not weak. My thoughts are also that the pump just works. It gets it's power from the engine and cannot get anymore or less than what the engine is putting out. If fuel makes it through the pump, great, if not, great - the pump doesn't work any more or less.

Maybe I'm thinking about this too simply....

Has anyone here had issues with their pump running dry at only 1/4 tank?

Now, if the pump was run off an electric motor, the load on the motor may change throughout the tank....the motor would wear out, not the pump head.
 
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DeafBug

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Audi5000TDI said:
1. Put 5 gallons fuel in your tank.

2. Pull your engine cover

3. Look at your injector pump.

4. Find the black fuel return line from your #4 nozzle to your injector pump. This should be located at the highest point on the Injector pump fuel body.

5. Beg, steal, borrow.... or better yet buy a $30.00 vacuum pump with a gauge and a reservoir.

6. Suck the fitting on the injector pump until you get no air bubbles.

7. Reattach the fuel return line hose from nozzle #4

8. Start it up.
7.4 Loosen two or three nuts on injector lines at the nozzle with 17mm wrench. Crank the car up until it is spitting fuel. (Nice if you can do all 4 but sometimes it is hard to get the 4th one.)

7.6 Tighten the nuts to a good handtight. Don't overdo it.

(Otherwise the pump will be cranking until it gets air out of the lines before it fires.)
 

Rickstah

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Audi5000TDI said:
Chemboy.... go suck a water column up 10 inches vertical versus 10 feet vertical, plus suck it through a fuel filter that provides resistance. That's what your injector pump has to deal with.

1.5 gallons is bottom of the tank... 10 feet vertical column up vs 15 gallons 10 inches of vertical lift.... Do the math on the fuel column.

I don't understand this, although I do know about the principle of lifting liquid via a vacuum...the part I don't understand is how it could be different if the tank is full or empty...isn't the tip of the fuel line in the tank always in the same place, at the bottom of the tank, so fuel would be siphoned from the same place all the time? If it was a full tank, is it possible the pressure is greater at the bottom of the tank, therefore fuel would take less vacuum to pull up the line? Teach me...:confused:
 

TooMuchBoost

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My PD has ran out a few times thanks to the sorry gauge.

Simply add 1 gallon of fuel and spin it over for 5 seconds at a time for 5-10 times.
 

whitedog

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Rickstah, you have it correct.

If it was a full tank, is it possible the pressure is greater at the bottom of the tank, therefore fuel would take less vacuum to pull up the line
Remember this term: Head.

The pump is not sucking fuel. It is only lowering the pressure. The height of the column of fuel provides weight which PUSHES the fuel INTO that lower pressure. The weight of that column is called Head. (Or is it the height above the pump?) The greater the head, the less the pump has to lower the pressure. Imagine if the tank were mounted directly over the engine. Then you would have an even greater amount of head and may not even need a transfer pump. Whether or not you needed a T-pump would depend on how much head you got and how fast the fuel is sent to the injectors.
 

whitedog

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TooMuchBoost said:
My PD has ran out a few times thanks to the sorry gauge.

Simply add 1 gallon of fuel and spin it over for 5 seconds at a time for 5-10 times.
Have you ever tried just turning the key on and not turning the engine over?
 

TooMuchBoost

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whitedog said:
Have you ever tried just turning the key on and not turning the engine over?
Thanks! I left out/forgot that I cycle the key on and off about 10 times before I actually try to crank it.

The cool part about this PD vs. my last 6.0 PSD is within seconds it runs smooth and normal.
 

RichC

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TDI_SC said:
This is the tool that really comes in handy. Attach the business end of the hose to the output-to-tank of the fuel filter, and pump away, until there are no more air bubbles.



http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92474

JP
That's the exact product that is sold at Sears Hardware for $40 ... or occasionally in the discount bin for $30. It seems well made but have found myself using the Pela 6000 and the adapters from this pack more that the 'MityVac' itself. (its probably operator error, but the older plastic MityVacs seem to work better? Anyone?)
 

Rickstah

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whitedog said:
Rickstah, you have it correct.



Remember this term: Head.

The pump is not sucking fuel. It is only lowering the pressure. The height of the column of fuel provides weight which PUSHES the fuel INTO that lower pressure. The weight of that column is called Head. (Or is it the height above the pump?) The greater the head, the less the pump has to lower the pressure. Imagine if the tank were mounted directly over the engine. Then you would have an even greater amount of head and may not even need a transfer pump. Whether or not you needed a T-pump would depend on how much head you got and how fast the fuel is sent to the injectors.

Good reminder, thanks. Does this imply the pump is of a variable nature, able to sense pressure in the tank, or does it just function at a constant rpm and vacuum? If the former, a neat piece of technology, if the latter, then...?
 

weedeater

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the PD cars have an electric fuel pump in the tank (along with the mechanical pump on the motor), hence I believe that priming is not required.
 

whitedog

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Rickstah said:
Good reminder, thanks. Does this imply the pump is of a variable nature, able to sense pressure in the tank, or does it just function at a constant rpm and vacuum? If the former, a neat piece of technology, if the latter, then...?
Fixed displacement, running at engine speed. I'll get a picture of what's happening with the Tandem pump here in a moment.
 

whitedog

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And a bit more information on the pump:



I believe part of what makes these so easy to start when air has been introduced to the system is the strainer and restrictor noted in the pictures.
 
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