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Re: New fuel pump no power, relay? Posted by Bernie [Email]  (#1501)  [Profile/Gallery]
(more from Bernie) on Mon, 17 Oct 2022 04:09:45
In Reply to: New fuel pump no power, relay?, Navid S, Sun, 16 Oct 2022 21:24:44 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Hello,
It is possible that the relay has failed but it is quite rare, but these cars are getting older. As far as there being 2 relays 1 is the main relay that powers the ecm then the ecm grounds the control side of the fuel pump relay which then powers the fuse for the fuel pump and then the fuel pump is powered.
The common issue for no power to the fuel pump is the crankshaft position sensor. The ecm needs to see the crankshaft position sensor signal before it will supply the ground to the fuel pump relay. Usually the quick check for the crankshaft position sensor is if the tach bounces when trying to start but I find a more dependable test is to spray carb clean or starting fluid in to the intake manifold through a vacuum line and if the car starts for a second the fuel pump is not being powered if it does nothing I lean towards a crankshaft position sensor because it also supplies the signal for spark. Another issue could be the electrical portion of the ignition switch not supplying 12v to the +15 circuit when in the start position or even bad battery cables that drop voltage below 10v when cranking which does not allow the ecm to turn on. Good Luck, Bernie
_______________________________________ George Riggin Specialty Automotive Current Saabs 1993 900 Turbo Conv. 1993 900 Turbo Conv. Auto 2003 9-3 Conv 2004 9-5 Arc Sedan 2005 9-3 SS 4 door 2005 9-3 SS Conv 2007 9-5 Aero Sedan 1986 900 Turbo Conv A few parts cars also
, Mon, 17 Oct 2022 04:09:45 <-- Viewing This Message, Mon, 17 Oct 2022 15:44:10
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