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Dave 86 930 Fl Dave 86 930 Fl is offline
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Join Date: Dec 2005
Location: 1000 Islands NY
Posts: 405
Originally Posted by ClickClickBoom View Post
Without talking to Dr Porsche, I will bet that the design philosophy is similar to many other 2 pump designs. The first pump is a delivery pump, high volume, low pressure. The second pump is a pressure delivery pump, high pressure, low volume. The reason you are experiencing the symptoms of quitting when you pull the relays is because the rear pump is not working at spec and unplugging the front kills the supply. The lean running on boost points at reduced high pressure fuel and the resulting lean condition. I would suggest plumbing pressure guages after each pump and check outputs against the FSM for your car.
The Porsche manual describes the process to check both pumps. I ordered a CIS tester today which will allow me to connect up to the rear pump and identify the bad pump, if there is one. I'm not convinced that I have a bad fp, as these cars are a bit tricky to diagnose and as a result, I'm reluctant to raise the victory flag just yet.
1986 930 - K27-7200, Andial Intercooler, Tial Wastegate, Electronic Boost Controller, B&B headers, Bodart Zork, Leask Adjustable WUR, Full Elephant Racing Suspension w/Adustable Spring Plates and Von Shocks, Wevo Transmission Mounts, Fuel Safe Fuel Cell, Forgelines (9"/11"), Hargett Shifter, Innovate AFR, Cobra CF Seats, DAS Rollbar, Coleman Floating Rotors, Lightweight Interior, Forgeline 17" x 9"/11", 2800 lbs.
Old 02-23-2009, 03:05 PM
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