I have a 1995 chevy blazer v6 4.3 vortec and it ran ok but we had to start it with starting fluid. We replaced the fuel pressure regulator and now it wont run for more than a few seconds. Everything is hooked up we replaced the fuel pump, map, maf, and tps sensors it seems like its not getting gas but theres no leaks. Checked the fuel pressure before and after fuel pump change and its the same 60 then it leakes down very quickly. The car is throwing codes 22, 34, and 43 for tps, map, and knock sensor. Could my knock sensor do this? Is there something else I should check?
1. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELIEF. Connect Fuel Pressure Gauge (J 34730 1) to fuel pressure connector. Turn ignition on. With ignition on and engine off, pressure should be
54 64 psi (3.8 4.5 kg/cm2 ) and should hold steady.
2. If pressure is within specification and holds, go to next step. If pressure is within specification but does not hold, go to step 4). If fuel pressure is not present, go to step 7). If pressure is greater than specification,
go to step 9). If pressure is less than specification, go to step 5).
3. Start engine. With engine at operating temperature, open throttle quickly and note fuel pressure. If fuel pressure is not close to64 psi (4.5 kg/cm2 ), replace CPI assembly. If fuel pressure is close to 64 psi (4.5
kg/cm2 ), problem does not exist.
4. Check for leaking injectors or fittings by pinching off fuel return line. If pressure does not hold, replace CPI assembly. If pressure holds, check for faulty in tank fuel pump or pump connections.
5. Check for restricted delivery line or fuel filter. Repair as necessary. If no restriction is evident, apply battery voltage to fuel pump test connector using a 10 amp fused jumper wire. For location of fuel pump test
connector, see COMPONENT LOCATIONS in SYSTEM/COMPONENT TESTS 4.3L article.
6. Gradually pinch off flexible fuel return line between CPI assembly and fuel tank. If fuel pressure increases to within specification, pressure regulator is faulty. Replace CPI assembly. If fuel pressure does not
increase with line pinched, check for faulty in tank fuel pump, loose pump connections or partially blocked fuel strainer.
7. Use a 10 amp fused jumper wire to apply battery voltage to fuel pump test connector. For location of fuel pump test connector, see COMPONENT LOCATIONS in SYSTEM/COMPONENT TESTS 4.3L
article. Observe fuel pressure reading. If fuel pressure is still not present, check wiring between test connector and fuel pump. If wiring is okay, replace fuel pump.
8. If fuel pressure is present with voltage applied to test connector, test fuel pump relay and voltage supply to relay. See SYSTEM/COMPONENT TESTS 4.3L article.
9. Relieve fuel pressure. Disconnect fuel return line. Attach a 5/16" flexible fuel line to CPI side of fuel line. Route hose into appropriate container. Turn ignition on, and note fuel pressure. If fuel pressure is within
specification, locate and repair restriction in fuel return line. If fuel pressure is still greater than specification, replace CPI assembly.
Also a new regulator doesn't mean it's good either. Also check battery and clean terminal ends. Load test battery
January, 5, 2013 AT 5:50 PM
I just was able to try this, this is great! I plugged the return line and it held the pressure so were going to go try replacing the fuel pump again we could have got a bad one. But thank you very much this was very helpful!
January, 5, 2013 AT 6:03 PM
Make sure your wires going to pum p inside tank are good as they have been know to fail.
January, 7, 2013 AT 6:48 AM
So I tried this and we replaced the pump but it still is not holding the pressure. If return is plugged it holds but when let through it does'nt.
January, 7, 2013 AT 2:47 PM
Only thing I can tell ya is try another fuel pressure regulator. Repeat steps 3-6 carefully and if it still doesit then i'd suggest taking it to a pro. Make sure you tell him everything that you have done though.