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1977 911S Fuel Problem
My project car has yet to start, and I know there is a fuel problem. I don't hear the pump whine, and no gas is getting back to the fuel filter. In the many posts and articles I've read I see this may be attributable to a relay problem, not necesarily the pump itself.
The relay installed in the fuel pump position is NOT the red relay, but one of the black relays found elsewhere. Could this be the problem? Is there a method for jumping the relay connections to test the pump without having to pull the pump and bench test it? |
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09-09-2006, 01:19 PM
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The relay for your fuel pump is in the front of the car under the bonnet (hood) but is the same as the one in the rear the easy way to tell is to remove the red one and the one from the fron and you will see that the same markings are beside each pin on the relays. You could reverse the wiring on the fuel pump which will cut out the AFR relay and cause the fuel pump to run constantly. Do not drive the car this way as if you are unlucky enough to have an accident the fuel pump will not shut off.
Richard.
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Life is not a journey to the grave with a pretty and well preserved body but to skid in sideways, used and worn out saying " What a trip! |
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09-09-2006, 04:33 PM
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Join Date: Jun 2004
Location: Rio Rancho, New Mexico
Posts: 1,325
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The black relay will work, but the red relay is better.
To test your fuel pump you'll need to remove the present relay and find the #30 pin in the relay socket. Look at the bottom of the relay for the pin numbers, then identify which pin in the socket is #30. With a jumper wire in #30 in the socket briefly touch 12 volts positive. You should hear the pump run. To test the relay, put your ohm meter across pins 85 and 86. You should read the coil. I would guess between 100 and 200 ohms. Another test of the relay would be to check between pins 30 and 87a. Should be close to zero ohms. This is the normally closed contact. Pins 87 and 30 are normally open. With the meter set for DC volts, at the fuel pump relay socket, pin 85 black lead and pin 86 red lead you should get 12/13 volts when cranking your motor. Or with the ignition on, lift the round plate at the air sensor and you should read 12 volts at pins 85 and 86.
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DOUG '76 911S 2.7, webers, solex cams, JE pistons, '74 exhaust, 23 & 28 torsion bars, 930 calipers & rotors, Hoosiers on 8's & 9's. '85 911 Carrera, stock, just painted, Orient Red Last edited by 2.7RACER; 09-09-2006 at 06:58 PM.. |
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09-09-2006, 06:56 PM
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Thanks for the tips. Evidently, not only do I have the incorrect relay, but after testing as suggested, the punp is bad also.
Oh well, I did buy it as a project car.......... Any other guidance for a new 911 owner is appreciated
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_________________ Dave Miller 1977 911 Targa 2.7 |
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09-10-2006, 09:05 AM
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1977 Porsche 911S Targa 2.7
