1997 sportage no start tc p0451

buckwert · 01-19-2008, 08:38 AM

my sportage quit while I was driving had it towed home and it is still sitting there I have spark my problem is a no fuel condition. I ran a jumper wire back to fuel pump and vehicle started right up. I do have a code reader and it gives just one trouble code p0451 which reads ( evaporative emission system pressure sensor/ switch range / performance) I am new to scanners and readers could really use a little help with a recommendation where to start checking thank you.

ron1004 · 01-19-2008, 10:46 AM

Welcome to the forum.

I would first clear the codes, and then see if any new ones come up - that code could be very old and due to the gas cap not being tightened correctly some time back.

I would start at the fuel pump relay that's found in the fuse/relay box in the engine compartment - try another one in its place.

An easier way to check the pump is to place a jumper on the diagnostic plug which is alongside the fuse/relay box across the B+ and PMP pins - I use a steel paper clip for this - this will bypass the relay and put power directly to the fuel pump.

buckwert · 01-19-2008, 12:54 PM

I have changed the relay with three different known good ones and no luck I had not thought of the diagnostic plug thank you I am assuming this code is not one that will prevent the car from starting? also I tried clearing the code and retightened the gas cap but it still reads the same code.

ron1004 · 01-19-2008, 01:33 PM

You'll need to track down the wire from the ECM that control that relay and confirm the continuity, and if that's in order then use a scantoll which can monitor the signals real time.

mgbgt1972 · 01-19-2008, 07:25 PM

When you crank it does it seam to crank more freely than before? Start by cleaning up all the conections, a bad connection or ground will cause this, also check the fuel filter.

buckwert · 01-21-2008, 11:03 PM

I know which wire runs to ecm (a red wire according to diagram) but do not know where ecm is located I cannot find a repair manual and the closest dealer (shudder) is 150 miles away. I have power to relay (30 and 85 or 86 the one coming from the other relay) but nothing out jumping across 85 and 86 puts power to wire for fuel pump (87) and O2 sensor (also 87) at least as far as the fuse panel in the passenger compartment. I am trying to trace on back to fuel pump ( I do know where the access is for that) I would also like to know what the other wires in that plug are if you know I would greatly appreciate the info. I am trying not to sound to incredibly stupid but I am kind of swimming around in the dark here. the diagram I have access to does not show the fuel pump wire connecting to anything but the diagnostic connection under the hood. the wire that goes to 02 sensors runs to the fuse panel in passenger compartment. I have been waiting for it to stop raining so that I can check under the vehicle for power to 02 sensors with bypass in place. Vehicle will still not start jumping 85&86 I think I have given you all the information I have any help would be greatly appreciated thank you.

buckwert · 01-21-2008, 11:07 PM

no it cranks the same and If I run a wire back to the fuel pump the vehicle will start

buckwert · 01-21-2008, 11:12 PM

the reason I know the relays are good is that my wife also has a Sportage (1996) which uses the same relays and my relays will start her car.

buckwert · 01-22-2008, 09:53 PM

no continuity on wire from relay to ecm my diagram shows nothing between relay and ecm would running new wire complicate things more?

sportage4x4 · 01-23-2008, 08:05 AM

the original wire may have broken at some point between the relay box and the ecm. running a new wire will not complicate things. just make sure to cut the existing wire at both ends.