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Guest Message by DevFuse

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Fuel Pump Question

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7 replies to this topic

#1 Guest_Future Subaru Driver 1_*

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Posted 06 May 2002 - 06:26 PM

here's my problem. my 1990 Justy has a bad fuel pump, the fuel pump is located inside the tank, for whatever reason..i dunno. Now.. instead of pulling the old fuel pump out, for convience sake, and also cause it's cheaper...would i beable to get an inline fuel pump from like any other subaru and put it under the car? and basically just leave the old fuel pump in the tank but not connected to anything power wise??

Would the in-line pump be able to "suck" the fuel through the old pump??

Would i get enough pressure??

#2 Guest_newbie boater_*

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Posted 06 May 2002 - 06:38 PM

The pump is inside the tank for cooling, it's usually immersed in fuel which keeps it cool. Many other reasons, just the first one I thought of. You should be able to add on an external pump, if you can find one of the right capacity and pressure, but you'd probably need to remove the old pump from the tank and install a straight hose in it's place, they have passages inside them that open and close as they spin, it may or may not be in the right location to allow sufficient flow. Make sure and wire the external one the same way as the old one was, through a relay, with a cut-off for the relay if the engine isn't running. You may also need to get an adjustable external regulator to keep the pressure where it is supposed to be.

#3 Guest_bbitner_*

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Posted 06 May 2002 - 07:06 PM

You cant pull fuel threw a shot fuel pump.

#4 Guest_newbie boater_*

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Posted 06 May 2002 - 07:14 PM

Generally, it's the electrical portion of a fuel pump that fails, not the mechanical components. If he can remove a fuel line somewhere, blow through it back to the tank as someone else stands by the open filler neck and listens for bubbles, the pumps fluid passages are technically open, but they may not be open far enough for it to be able to flow the required amount of fuel for proper operation of the engine. Then again, I am speaking in generalizations. If there is something inherantly different about the Soobie fuel pump I am not aware of, I'm always open to learning new stuff. Please explain why it shouldn't work?

#5 Guest_Bill Putney_*

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Posted 07 May 2002 - 11:16 AM

Before you can make these generalizations, first you have to know if it's a turbine, gerotor, or roller vane type pump. Some types you can pull fuel thru, others you can't.

#6 Guest_newbie boater_*

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Posted 07 May 2002 - 11:22 AM

Very true, and without having one sitting here, I'm not going to venture a guess as to what design it is. So I revert back to my original post, stating that he'd probably have to remove the old pump first.

#7 Guest_Hondasucks_*

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Posted 07 May 2002 - 11:35 AM

He also did not state whether or not his Justy is fuel injected (did the Justy's come with EFI???) beacuse although a carburetor only requires maybe 10 psi if that of fuel pressure, EFI can require up to 50-75 psi, which an aftermarket fuel pump (unless it is an EFI fuel pump, which I've never seen in an auto parts store) can not provide. Most EFI systems require a minimum of 45 psi to function properly. If iit is in fact carbureted, then yes, you can bypass the tank-mount fuel pump (if it is the type that will allow fuel to flow through it without it being powered) and add an aftermarket. The older subarus, with the fuel pump in the engine compartment, had an integral pressure switch that would shut the pump off once it reached a certain pressure, and turn it back on when that pressure dropped. I think they used that pump up till MY 81. Gen 1 cars had the pump bolted to the firewall next to the spare tire well, it's a small round device with 1 or 2 wires going to it and 2 hoses. Gen 2 cars had the pump mounted to the rear of the driver's side strut tower. Even though they quit using the underhood pump in 81, my 84 has the threaded mounting holes for the pump bracket.
You can put the pump on a toggle switch, or, as I did, run it off the positive side of the ignition coil.

#8 Noland


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Posted 23 September 2003 - 03:29 PM

I have a 91' Justy 5 speed US model, manufactured November 1990. The fuel pump is under a shield on the driver side (LEFT SIDE) of the vehicle. The shield is attached with three 10mm bolts
The bolts have an anti-vibration rubber washer.

The pump and fuel filter is mounted on the back side (up side) of the shield.

I recommend that you change the fuel filter far more often than Subaru says, I have the best results with Chevron's lowest grade of fuel. The price difference has been worth it, as the valves and carb and super clean, this after 140 thousand miles.

I have also been using the car since it's purchase at 60K miles, and use Valvoline 10W-30 Durablend.

I have excellent compression in all cylinders, and I have seen no, (and I mean none) metal flakes in the drained oil.

Let's here it for the synthetic blends, they really are worth the extra money, going for about $2.20 or less a quart.

Best Wishes

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