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Bad CPS? Or broken wire to CPS? Posted by MI-Roger [Email] ![]() ![]() In Reply to: saab 9-5 1999 automatic no power to fuel pump .. help, Marek c., Sat, 13 Mar 2010 09:37:42 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Assuming your testing of the fuel pump is correct, two different signals activate the fuel pump.
1) As you turn the key to start the engine, the fuel pump receives a brief signal to activate to prime the fuel system. This signal only lasts for a few seconds.
2) As soon as the engine starts, the CPS will "see" the crankshaft rotating and initiate the continuous run signal to the fuel pump. If the CPS has failed, this continuous run signal is never issued and the engine willl die due to no fuel. The CPS usually fails intermittently at elevated temperatures(i.e. no re-start when engine is hot), but it doesn't always fail with hot re-start only.
Bad relays, broken wires, failed fuel pressure regulator, plugged fuel line or filter, are all additional potential candidates.
If your fuel pump is original, I would test it a second time to be sure it is really still good.
posted by 98.250.156...
_______________________________________ Saabs owned: 2008 9-5 Aero Sedan, sold at 227K miles 2006 9-3SC 2.0T - Wife's daily driver 2000 Viggen Convertible - Sold May, 2022 1964 Quantum IV Formula Car - Retirement project 2000 9-5lpt Sedan, sold at 318K miles
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