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check fuel system pressures and electric connector Posted by walt [Email]  (#2707) [Profile/Gallery]
(more from walt) on Mon, 23 May 2011 07:40:09
In Reply to: Fuel system struggle, diagnostic question., Cary, Mon, 23 May 2011 06:12:45 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Check fuel pressure at fuel rail near thermostat. Should be 2.5 bar. If it's low, injection is too lean to start engine. Could be caused by foreign debris clogging 2.5 bar pressure regulator at other end of rail. Momentarily pinching return-to-tank fuel hose from regulator sometimes flushes it out. Gauge should show almost 6 bar when pinched. If not, then check fuel pressure directly on "pump" fitting in fuel tank. If pressure is not close to 6 bar and pump is not wired backwards electrically, then power pump with a spare battery and a fresh wire harness (watch for sparks by connecting/disconnecting power at battery not in trunk!) and re-check pressure. If pump puts out normal pressure when hot-wired to battery with a fresh connector, most likely that in-car electrical connector at pump is corroded and needs replacement. If still low pressure, then new pump is bad, has incorrect polarity on wiring, or is leaking on plumbing connections inside pump plastic canister or something plugging outlet. Also the pressure check at fuel rail will tell if the check valve at "pump" connection of fuel pump is holding residual pressure. If not, engine needs to crank 5 to 10 seconds to build up pressure, unless the fuel pump fuse is jumpered. Car probably will start if pump fuse is jumpered and air mass meter is disconnected, and will continue to run badly once air mass is re-connected, jumper replaced with 20 amp fuse, and oxygen sensor heats enough to enable fuel computer to run in closed loop mode.
posted by 72.49.6...
, Mon, 23 May 2011 07:40:09 <-- Viewing This Message
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