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rc7424 · Posted: Tue Aug 11, 2015 10:50 pm Post subject: Fuel Pump Testing

'82 931. Fuel Tank Cleaned. New Fuel Pumps and Filter. Accumulator seems good. Want to test fuel flow to fuel distributor and clean out hard fuel lines.

How do I light up the fuel pumps without cranking the starter? Would prefer not to pull the relay. Can I run jumpers from the battery to the pumps?
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Autonomous Vehicles are for Automonous People

'82 931
'22 Alfa Giulia
'21 BMW 840
'02 Ducati 998
'11 FXDWG
'75 Honda 750 F

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Pull the relay.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

The fuel pump power wire is the fat black/green wire that runs from the fuse box area, under the drivers door sill to the left side of the hatch, then across the hatch floor just behind the rear folding seat, and down and out the hole in the floor to the right side of the hatch floor under the carpet to the fuel pumps..

I installed a 3 way switch in this wire under my drivers door sill when I was first getting my car sorted so I could manually power the pumps with the switch wired like this.
1- standard FP relay wiring
2- off
3- direct +12v power

I don't see why you couldn't jump it with a wire all the way to the FPs but that's quite a long ways, simply jumping pins 30-87 on your OEM FP relay should easily do the trick. I used a switch because I was needing it often....

The FP ground runs across the hatch floor like the power wire, its the fat brown one, but instead of turning forward it turns to the rear of the car and grounds on a ground crown of male spades in between the tail lights under the rear wall carpet section more toward the driver's side (left) tail light..
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80 Turbo - Slightly Modified

rc7424 · Posted: Sat Aug 15, 2015 11:41 am Post subject:

I pulled the fuel pump relay and jumped 30 and 87. The internal pump lights up. The external pump does not. My multimeter says both pumps are getting power.

Is there something else that fires up the external pump, i.e., the flow of fuel into it? Or does it sound like the pump is toast?
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Autonomous Vehicles are for Automonous People

'82 931
'22 Alfa Giulia
'21 BMW 840
'02 Ducati 998
'11 FXDWG
'75 Honda 750 F

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

did you also jumper the pressure sender on the intake?
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Check the ground wire from the external pump to the body. If that's OK it is probably the pump itself.
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

rc7424 · Posted: Mon Aug 17, 2015 12:05 am Post subject:

Toofah…not a clue.

Fiat22…haven’t seen anything about jumping fuel pressure sender on the intake. You mean the fuel pressure regulator?

There is no ground from the fuel pump to the body. It has positive and negative terminals with positive and negative leads from wiring harness.
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__________________________
Autonomous Vehicles are for Automonous People

'82 931
'22 Alfa Giulia
'21 BMW 840
'02 Ducati 998
'11 FXDWG
'75 Honda 750 F

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

The negative wire should go to ground. Use an ohm tester to make sure it isn't shorted.
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

http://www.924board.org/viewtopic.php?t=22724
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

The 4th paragraph of Fiat22's link gives the location of the ground. Check it or not it's your choice.
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

rc7424 · Posted: Wed Aug 19, 2015 1:33 pm Post subject:

Thanks for the link. Big help!
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Autonomous Vehicles are for Automonous People

'82 931
'22 Alfa Giulia
'21 BMW 840
'02 Ducati 998
'11 FXDWG
'75 Honda 750 F

rc7424 · Posted: Sun Aug 23, 2015 9:19 am Post subject:

Fuel is pumping furiously. Fuel line internals have cleaned up nicely. Thank you all!

Any recommendations for a good inexpensive shop to rebuild fuel dizzy and WUR?
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__________________________
Autonomous Vehicles are for Automonous People

'82 931
'22 Alfa Giulia
'21 BMW 840
'02 Ducati 998
'11 FXDWG
'75 Honda 750 F

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi