Draining Old Gas - Use Fuel Pump

[John Nordling]

I drove my 90 Q45t home and parked it on the day I bought it last August. Just too busy to finish it in a whole year!

These forums have guided me through chain guide replacement, oil pan R&R and oil pump replacement, motor mount replacement, F&R shock replacements (with ALL rubber parts), front upper control arm replacement, front tension rod bushing replacement, steering rack boot replacement, tie rod and tie rod end replacements, F&R swaybar bushing replacement, exhaust system rubber hanger/mounts replacement, transmission mount replacement, regular and auxilliary transmission filter replacement, resealing valve covers, and of course, the dreaded plenum job with all hoses, sensors, and injectors. In all, about $4,500 worth from Joe in Scottsdale.

All is now done except replacing the plenum even though I have all of the parts. It has been so long that I do not wish to rush the job. My heartfelt thanks for the invaluable advice and esprit de corp that this forum offers. It has kept me sane for the last year.

Now the question. Because the fuel in the tank is a year old, and especially because I didn't immediately put an additive in it to prevent the fuel from breaking down, I want to drain the tank. Can I do this using the fuel pump by undoing the fuel line in front of the fuel filter and hooking up a hose to a portable gas can and then turning on the ignition key? I am concerned that this may damage the fuel pump or the ECU when no pressure is in the line.

Alternately, does anyone have another solution? To my knowledge, there is no drain plug on the bottom of the tank.

As always, your help is greatly appreciated........John;)

[DAEDALUS]

You mean you want to crank the engine till the tank is drained? Seems you'd do more damage to the starter than the pump. I recently used my old Q pump to drain a full 22-gallon tank from my truck after its fuel pump failed. My old pump has about 190k miles on it, hums a bit, but did the job without a problem on 12v. I thought being in air it would be at least a bit warm on the outside when I was done, but I couldn't feel any warmth coming off it. I'd probably jump the pump to run it, and be careful to shut it off right away as soon as the sound changes, indicating its running dry.

What if you ran a fuel hose down near the ground and put the key in for the 3-second run...would the tank slowly siphon out completely?

[Aus94Q45]

I understand your thoughts of pumping it out with the pump, and there may be a way to do it with the pump in place. If you disconnect the fuel line and turn the key to the on position, would it continue to pump in an effort to pressurize the system? Could you disconnect the pump from the controller and jump it to run?

If not, I would use a manual pump or siphon it. Electricity and electrical sparks around 93 octane is asking for trouble. Take extreme precuations when using any electrical source around fuel. I know two people who have suffered substantial burns while working on fuel lines/tanks. In both circumstances an electrical spark ignighted the vapors that gathered. Neither could believe that the vapors flashed. Be careful.

[squeefoo]

I ran the return line w/extension to a container, and ran it until it died. However this is not what you are trying to do. Sounds like a direct wire to the pump is the best thing to try, w/the same extension for the feed line. Less screwing around, -you cannot get a siphon tube into the tank on this thing ; it's a waste of time I know -I wasted a lot of it trying. Somewhere on NICO is an explanation of the harness or in the FSM. AUS 94 is right on.

[John Nordling]

I just wanted to turn on the ignition and use the pupmp to run the tank dry. Since the plenum is still off, none of the fuel lines are connected past the fuel filter. I thought I would undo the new line I installed to the filter and connect it to a gas container. Nothing esle would be turned on electrically.

Daedulus - you've helped me out before. Thanks! i don't have a spare pump, but I'll try your idea first. Sounds like the pump runs for three seconds when turned on to stabilize pressure. Is that true?

Aus94Q45 - Thanks for the cautions; I'll be careful. I've had gas tanks out before on other cars, but each situation is a new challenge. I'm hoping the pump will run with the key on and no pressure. If not, where is the "controller" you mentioned?

squeefoo - If the pump won't run under a no pressure situation, I'll try your idea of a direct 12v power line. I had guessed that a siphon wouldn't work with the baffles modern gas tanks have. Thanks for the confirmation.

Hey, any way to tell if the fuel pump is working properly while I have the car apart? Not that I want to spend any mpre mpney, but it sure would be easy to do because I have the trunk apart and the seats out of the car being cleaned up.

[squeefoo]

The box which connects to the wire bundle, which runs to the fuel pump is the controller. (hope that made sense) If the pump hums loud enough to hear while you're driving or idling (unfortunately with everything -i.e; seats, package shelf, etc. installed) it's a candidate for R&R. I know there are threads on finer points of determination. Do a search. I think somebody figured out the amp draw between good and bad. A place to look is the pin on/in side the controller, take the cover off and look to see if any pin connectors got hot (and at the circuit board). BTW It's not that hard to get at once you've done it -and you've done it!

[DAEDALUS]

Sounds like the pump runs for three seconds when turned on to stabilize pressure. Is that true?

Yeah it's timed. 3-5 seconds, it assumes that will be enough between the pump and the regulator. I kind of doubt gravity will be able to siphon out the gas past the fuel pump. Wishful thinking on my part.

[John Nordling]

Thanks, folks. I'll be trying this on Monday night and let everyone know how it worked out.

You guys are great for us novice DIYers!

John

[Q451990]

I've absolutely flooded the valley to the point that I had a stream of gas running down the driveway during my first injector/plenum job. Just leaving it sitting in the sun without unscrewing the gas cap built up enough pressure. The lines will also siphon out if you just remove the fuel filter and let the line hang lower than the car in the front. Discovered that when I replaced the fuel tubes on Q2. I'm not sure if you'd get all of the gas out with either method though... and it would certainly take a while.

How full is your gas tank? To be honest, when I did the work on Q2 I just left the old fuel there for a year or two, and didn't have any trouble at all. But it sat with about an 1/8th of a tank, so I filled up quickly after I left the garage, so the old stuff was diluted quickly.

Your overhaul sounds a lot like mine... new shocks, rubber, brake rotors, pads, exhaust hangers, fuel pump, suspension rubber, etc. It took me from October of 2001 to October of 2003 to actually get it done and down to T3 for guides!

Congratulations on being almost done... it'll all be worth it!

Heath

[tangalora]

Maybe this is just the weasly way out, but I'd first try a basic siphon consisting of, at its simplest, a plain 'ole six foot section of 1/2 or 5/8 inch diameter garden hose (or similar).

Actually, I'd just burn the gasoline off, personally, but that wasn't the thread question (and I have so many questions that I try to pay special attention to those that are asked).

The first siphon job I'd attempt is thru the fuel filler nozzle. I'm assuming you already know that won't work (theft prevention baffles or whatever). I would think a thin enough hose (1/4 inch or so) should work - but I never tried that & I assume you know it won't work.

So, the next logical siphon job I'd suggest is to simply follow the three steps below after removing the trunk bulkhead (between the rear verticle seat back and the trunk room) and after positioning a 16 oz bottle of gator aid or scope or equivalent nearby.

a) Disconnect the battery, the fuel lines at the fuel pump, and remove the bolts holding the fuel pump to the fuel tank.

b) Pull out the fuel pump just enough to get a garden hose (or equivalent) past the opening (it's a straight shot to the bottom of the tank from there) and into the fuel tank (see photo attached).

c) Suck air to dinosaur juice until the taste gets real bad, and then hold the gushy end of the garden hose lower than the fuel tank itself. (Here's the part where you then swish the gator aid or scope or whatever to alleviate that wonderful taste in your mouth and aspiring lungs.)

I don't see any reason why that won't work. In my next post, I'll suggest a method that actually uses the fuel pump (which is, after all, what you had asked in the first place).

[tangalora]

OK, so you really wanna use the fuel pump to pump out the petrol. Be that way.

Here's how (I think you can) coerce the fuel pump to pump incessantly (forget the 3-second turn-on rule).

After removing the trunk room bulkhead (see prior post) ...

a) First, disconnect the fuel pump control unit harness connector from the fuel pump control unit connector (both located on the top right side inboard of the right speaker behind the cell phone and CD changer, if installed).

b) Then just jump the ground connection (#4 wire) of the fuel pump control unit harness connector to ground (see photo) using a 1 foot 16AWG wire to carry the 5 or 6 amps (I forget exactly how much but I posted it previously so a Nico search will find the current draw).

c) Disconnect the fuel line at the inboard side of the fuel filter in the engine compartment.

When you turn the ignition key to ON (which will complete the 12v circuit for the fuel pump, thereby running it constantly) I suspect this will pump your fuel tank dry of carboxcyclic benzene as the summeritme Salt River in Phoenix is of dry of dihydrogenoxide.

This seems too easy, so, I will admit up front that maybe I missed sumphun'. Jes' be gentle with me if I did.

[tangalora]

Here's a shot of the inside of my 1990 Infiniti Q45 fuel tank looking down the hole previously filled by the fuel pump.

Notice, despite the extensive baffling to the sides, there is a straight shot to the bottom of the fuel tank from the fuel pump opening circle.

I would guess that a siphon stuck straight down two or so feet would bottom out on the floor of the Q45 fuel tank (allowing all, or most of the smelly stuff to be siphoned out efficiently).

[tangalora]

I realize (being a novice) that the LOCATION of the fuel pump control unit, the fuel pump control unit connector (which is integral to the fuel pump control unit), and the fuel pump control unit harness connector is somewhat of a mystery to those who never saw one before (it was to me, especially as it's hidden way back, way up, behind the CD changer and telephone amplifier and tucked away next to the right rear speaker and covered by the package binnacle in front).

Basically that sucker is hiding better than George Bush did from the National Guard role callers back in the 60s. To be politically balanced, the fuel pump control unit hides better than John Kerry does from his political record. You have to dig and push things aside to find it.

Here's (what I think is) a good shot of the fuel pump control unit (circled in blue) along with the fuel pump control unit harness connector (the white disconnected connector) to which you'll jump the 16 or 14 AWG one-foot wire to ground.

[Chally]

Seriously, put the garden hose into the tank & syphon it out.

If you can get it down the filler spout, it will normally pull out. If you can't get it down there, lift the pump, as shown, & put the hose in there.

Try & avoid using the pump with jumper wires etc, as any spark may negate any reason to do anything else. (BOOOOM!!!)

It doesn't matter if you can't get all the fuel out, as the new fuel will dilute it enough. In reality, the fuel in the tank will still start & run the engine OK, even after 12 months. Because it is a closed system, (and it stayed closed) no contaminents should have got in.I don't know how bad your fuel is there, but if the old fuel smells like wood laquer, it may be a good idea to take the tank out & give it a flush with clean fuel.

[Q451990]

If the tank is under 1/2 full, I think I'd just add 5 gallons of fresh fuel with a gas can to dilute it a little, and then drive it...

Heath

[elwesso]

I dont know if this was mentioned, but when you turn the ignition on from OFF it will prime the pump and will stay on for about 5 seconds.... you could just keep doing that!

[tangalora]

Quote »any spark may negate any reason to do anything else. (BOOOOM!!!)[/quote]While this is very true, possible, and would hurt a lot, I don't think it's very likely.Then again, I'd ask those experienced if they know of this happening ('cuase there's nothing like the real world).

The reason I think it unlikely is that it's a closed system, designed to be a closed system, with the full knowledge of the fact that sparks can and do occur ... and look'it at the picture, with wires galore all over the place (that circled box at the left is the left-rear speaker, but there's a trunk lamp right above the fuel tank, and, in my Q45, a telephone & CD changer box to the right, the right-rear speaker (which, I'm told goes on fire every once in a while), etc.

[tangalora]

Quote »put the garden hose into the tank & syphon it out ... If you can get it down the filler spout, it will normally pull out. If you can't get it down there, lift the pump, as shown, & put the hose in there.[/quote]I can't agree with you more on that. If someone really needs the gasoline out of the tank w/o removing the tank itself and spilling its guts, why wouldn't the basic siphon in the fuel inlet tube work?

Looking at the picture below, the fuel inlet circled on the right of the photo is pretty large (from the outside anyway) and barely kinked (again, from the outside).

QUESTION:Why can't a 1/4 inch siphon be used from the fuel inlet to the bottom of the fuel tank?

[Chally]

Quote »Then again, I'd ask those experienced if they know of this happening ('cuase there's nothing like the real world).[/quote]Being a mechanic/technician for past 23 years. Sorta know about fuel & what it takes to blow. Yes, there are lots of wires etc around the tank, but that's OK because the fumes are in the tank & sealed in! Fuel itself doesn't burn, it's the fumes that burn, that's why the fuel has to be atomised properly to get maximum performance, etc.

I must say, the likleyhood of an explosion happening may be low, it's always better to minimise it as low as possible.All you need is a little oxygen in the tank to create the right mixture to blow your head off!!!Running an electric motor in an open situation is not too smart or recommended.