vaportrail |
08-23-2009 07:52 PM |
Fuel Pressure reading clarification
1997 Blazer with 160K miles. Misfires at idle terribly. Swapped out all electrical (Coil, Cap, Rotor, Plugs, Wires) except for the Ignition Module. Distributor gear looks good (Had it out for an intake gasket change). Not much play on the rotor. When I watch the TECH2 misfire screen it is typically either cylinder 3 or 5 (Usually sets a P0300, however). Seems worse when car is hot. Misfire will lessen / quit if I rev the engine at idle to about 1500 rpm.
Trying to decide if the fuel pressure readings are OK or not. Followed the book method post. When the pump primes and the pump is running, I am at 60 psi. After the prime, it drops to around 55, then seems to rise slightly to 56, sometimes 58. When idling, the pressure bounces a bit but is at 52 -53 psi. If I stab the throttle, it'll jump to 60 psi, then return back to the 52-53 value.(Are these acceptable?) I did install a new filter, but achieved the same readings.
I also did an injector balance test and pressure went from 57/58 to 48 psi after the pulse on all injectors, so I could not see any difference. Trying to either rule out the fuel pump or not. Thinking it may be the spider assembly based on many of the posts.
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