Mechanics

WONT START - FUEL PUMP?, PRESSURE

1999 GMC Savana

Engine Mechanical problem
1999 GMC Savana V8 Two Wheel Drive Automatic

1999 GMC 2500 SAVANA 5.7 vortec- wont start.
replaced plugs, rotor, cap, cam position sensor.
turns over, and has spark, and fuel at rail.
Could it be the fuel pump?
What is fuel pressure suppose to be and how do I check this?
Steps to replace?
Avatar
Plumbr7
January 8, 2009.



Hello,

Fuel Pressure should be 60 - 66 PSI. I believe the test port is on the back driver side of the intake manifold. Check out the video link below it will explain how to test fuel pressure and how to test the fuel pressure regulator....

http://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm

Post finding here......

One more thing you say it has spark, ok, now what color is the spark? If it is a yellowish/Orange you have a weak spark which will cause a no start problem. The spark should be a bright Bluish/White..

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Obxautomedic
Jan 8, 2009.
What causes a weak spark after installed new cap and rotor and ignition module, spark plug wires and spark plugs and ignition coil, new alternator, new battery and battery cables. The van has no trouble codes, only the p1351 which high voltage coil or misfire, but could that code be from the old fuel injector poppet system problem not providing enough fuel to the cylinders? The engine was running fine with this code but the engine light didn't come on. I did replace that with the new system scfi to mpfi conversion that gm had problems with from years 96-2002. Do you have any idea what might be cause my spark plugs put out a orange spark instead of bluish white spark? Please help me out.

Tiny
Sonny721
Nov 1, 2009.
Hi Sonny721,

Here are a couple thing to check.

This next test will tell us if the primary ignition system is supplying an electrical trigger pulse to the ignition coil. To test the ignition trigger pulse remove the small wires from the coil. Using a voltage multimeter connect the leads to both wires and set the multi meter to DC voltage. Next have a helper crank engine over and observe the voltmeter, if the meter jumps from 12 volts and then to zero in rapid succession the trigger system is working properly. Next check the ignition coil for corrosion if no corrosion exists use the voltage multimeter to test the coil primary and secondary circuits for continuity and resistance. This testing procedure will work for most automotive coils. With all wires disconnected from the coil, use a multimeter switched to ohms and check the resistance between the small side terminals of the coil. You should get a reading of 0.75 to 0.81 ohms of resistance. Then check the resistance between on either side terminal and the center high output terminal. The ohms reading should be about 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate the coil is shorted and needs to be replaced. If there is no primary ignition trigger output proceed to next step.

Step 7 - If the ignition coil has no trigger pulse input the primary ignition system has failed. This system contains a crankshaft position sensor (CKP), camshaft position sensor (CAS) which is a low voltage generating system (1.5 to 3.0 volts) and is then amplified to 12 volts by using a ignition module (amplifier) and then transferred to the primary side of the ignition coil. The ECM (engine control module) controls the engine ignition timing by advancing and retarding the primary trigger signal to the ignition module. You might say " if the crankshaft position sensor (CKP), camshaft position sensor (CAS) has failed wont it produce a diagnostic trouble code?&Quot; the answer is " not always" this is because some computer systems think the starter has failed or you have left the car in a drive gear or the clutch not depressed completely, not allowing the engine to crank over. In this case the computer just thinks the engine is not cranking over, even though it is. First turn the key to the on position, with the ignition coil connected to its wiring. Then, using a test light or a voltage multimeter ground one side of the test light or meter and test the coil terminals, there should be power on both sides of the coil. If the coil doesn't have power, locate the main computer system control relay and replace it with a new unit and re-test. If 12 volts is present continue to the next step.

Step 8 - Locate the crankshaft position sensor (CKP) and camshaft position sensor (CAS) (note: if your engine is designed with a distributor sometimes the CAS is inside the distributor housing) disconnect the wiring connector to probe the connector, there are three wires on most of these sensors so three tests are needed. Set your multimeter to ac voltage and probe any two wires on the sensor side, have a helper crank the engine over you should observe the multimeter jumping between 0 and 2.5 volts on two of the three combinations. Continue testing until three pairs of wires are complete. (I.E: right outer and center, left outer and center and right and left wires) if no pulse is present remove the sensor and observe inside the mounting port with a flash light. While looking inside the port have a help crank the engine over, you should see a small hole or magnet used to trigger the sensor, if this trigger is present replace the sensor. Perform this test for both sensors if equipped, if the sensors test ok suspect the ignition module (amplifier) or ECM.

Mark S

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Obxautomedic
Nov 1, 2009.