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fuel pump circuit help needed!
1986 930 with &#%$!! intermittent fuel pump running.
Even when I disconnect the connector at my air flow sensor on the CIS, and turn the key to run (position #2), my fuel pumps usually do not come on right away. I say usually b/c sometimes they do, sometimes they don't. Sometimes it takes several minutes and then the pumps suddenly start running! Same thing with the wire coneected and me pushing down on the air flow sensor plate; sometimes the pumps kick, sometimes they don't. I ascertained that I have power on both sides of the fuel pump fuse when the problem is occurring. Question #1- Does that mean that my red relays have done their job and are not suspect??? Question #2, what switches/relays etc can interrupt the 12V from getting to the pumps after the the 12V I know I'm sending down the wire from the fuse panel? I have pulled every relay and fuse and spread them, cleaned them, and wiggled them all during the problem... nothing. Pulling my hair out in NY... |
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07-13-2003, 07:13 PM
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Join Date: May 2001
Location: Peoples Republic of Long Beach, NY
Posts: 21,140
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I don't have a 930.. so I may be off base here.. your circuit may be different that the simple K system, with one fuel pump relay. the fuse gets its power from the ignition switch for the "on" sw. position, but not the "start" sw. position.. ign. sw. contacts get toasted.. maybe when this happens next time run a hot jump to the relay 87 for the "start".. and 87a for the "on".. after your sure your relay is working correctly............Ron
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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07-13-2003, 07:59 PM
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Thanks Ronin. Check it when I get home. Do the N/A 911s use the square yellow relay to detect air flow? My latest theory is that maybe mine doesn;t always sense that the air sensor plate has moved, and thus does not permit 12V to the pumps.
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07-14-2003, 10:01 AM
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Location: Peoples Republic of Long Beach, NY
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the air flow safety switch shuts down the engine by grounding the 85 pin on the pump relay.. but I don't know about the 930.. why not get a elec diagram for your model, and then start disconnecting possible problems and jumping other legs of the circuit? ..........Ron
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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07-14-2003, 11:55 AM
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Location: MA USA
Posts: 2,938
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I believe there are several things that can make the fuel pumps not work. One is the rev limiter. I think the 930 have the same one as the late SC's. It is behind the left front hood shock. Unplug that and see if you get a change. It is brown and rectangular. There is also an overboost protection circuit. Listen to Ron and get a diagram. It would really help you understand
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Dean 911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno, |
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07-14-2003, 02:37 PM
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Location: Peoples Republic of Long Beach, NY
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Quote:
that rev limiter to me is more stock electrical crap that can disable a circuit. I hate that. I don't even want to know about the overboost protection.. If I do ever have to know about it I'll e-mail you. .........Ron
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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07-14-2003, 11:16 PM
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Join Date: Dec 2001
Location: MA USA
Posts: 2,938
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E-mail away, my friend
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Dean 911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno, |
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07-15-2003, 05:07 AM
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911 Turbo
