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Old 12-11-2012, 12:28 AM
dsraven dsraven is offline
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trying to run the engine with starting fluid is not recomended.
find the fuel pump relay, on the firewall probably, and jumper it so the fuel pump will run when you want it to run. the grey wire goes to the fuel pump, the red wire is the fuel pump prime wire and if you power that up the fuel pump should turn on. the other end of the red wire should be somewhere near the brake booster. insert jumper wire there. the orange wire comes from the underhood fuse/relay box and should be hot at all times,it also heads over to the oil pressure switch to run the pump when the engine gets oil pressure if the relay craps out. if you can get the engine to run and you disconnect the fuel pump relay the engine should stay running if the oil pressure switch is good. the dark green/white is the wire that the computer powers up to turn on the relay, black/white is the ground to complete that turn on circuit. you can put a switch inline between the red and the grey for test purposes. this takes the relay out of the system and if you have some long wire it allows you to be under the truck and turn on/off the fuel pump. it comes in handy if you are alone when testing. now power up the fuel pump and test the fuel pump outlet pressure and see what you have. 9-13 psi is what it should be. next, remove the fuel filter and run the pump, catch the fuel in a container. that way you will know if it is actually pumping a volume of fuel up to the filter or if it just has some pressure but the volume drops off as soon as there is somewhere for it to go, like the engine started. like a pinched/restricted fuel supply line can do. then, if that is good, put the filter back on but don't connect the outlet fitting yet. retest the volume again. if the fuel filter passes the test then remove the return line and see what you have coming back from the throttle body with the pump running and the engine off.
is the fuel return line pinched anywhere?
have you checked the egr valve? remove it, place it upside down in a vice or something so the gasket surface is level and it can't move around. now pour some varsol or paint thinner into one of the ports. does it leak out into the other port or down the shaft from the diaphragm? if so, replace the egr valve because it is leaking exhaust into the intake system and leaning out the fuel mix, or it is leaking vacuum through where the rod goes to the diaphragm and that is leaning out the fuel mix.
have you tried plugging off all the vacuum lines to eliminate a possible leak from a brake booster or another accesory?
have you tested the ignition module? a bad module will usually retard the timing a bunch.
is the fuel pressure 9-13 psi? more than that could mean you have a restricted return line. if so, remove the return line and check the pressure again. if it is right after disconnecting the return line then check for a restricted return line.
lower than 9 psi could mean you have a bad regulator. if you have good pressure at the filter but not at the throttle body then it could be a pinched/restricted line from the filter to the throttle body.
did you check the injector filter screens?
did you check the injector rersistance? should be 1.3 ohms at 140degrees F. (unplug wiring harness so you are only testing the injector itself).
have you checked the idle air control valve? it is a resistance check across A to B and then C to D, should be 40-80 ohms. A to D and C to B should be infinite. if not passing these tests replace the iac. also check the port and the seat that the pintle goes into for dirt or debris.
have you checked the pcv valve operation, the supply hose and the port in the throttle body for blockage? it should be a wide open port to manifold vacuum. they are known for plugging up the passage in the throttle body. you have to take the throttle body off and flip it upside down to check it, then you might as well clean it while you are there. the pcvvalve should rattle when it is removed and shaken. check inside for gummy deposits that could hinder it's operation.
have you checked the map sensor? should have a 5 volt refernce supply. if you put 10 inches of vacuum on the port the voltage should drop 1-2.5 volts. grey should be reference, lt green is map sensor input to ecm, black is sensor voltage return. output is dependant on altitude and there is a chart for reference, but basically you should see a change when you put vacuum to the port. check for a plugged/cracked supply hose.
i would check the egr valve first, personally. if you have the proper fuel pressure and are getting a good cone of fuel at the injectors then there is probably a vacuum leak or the egr is leaking exhaust/vacuum into your intake.
hope this helps.
keep us posted
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