WTF?? PLZ HELP!! What am I missing
- Thread starter Omzy88
- Start date
DaveP's Ghost
Well-known member
Does the check engine light come on with key= RUN? If = no, the ECM is not powering up.
Does it have an aftermarket "chip" in it? If = yes, I'm out. Especially a turbotweak.
Does it have an aftermarket "chip" in it? If = yes, I'm out. Especially a turbotweak.
thanks for the reply, yes the engine light comes on when you click key on, second click then goes away, try to start, cranks everything's spinning alternator etc.. no luck just cranks.. had a spare ecu tried that and the turbo tach reacted a lot differently.. ( it dropped down instead of middle) but still no change. put the original back in!! Its all original no aftermarket anything except for msd cap and rotor and taylor spark wires and ngk plugs!
graham1524
Well-known member
Have you checked your fuel filter? One thing to check would be fuel pressure at the rail if you depress the valve core in the fuel rail.
DaveP's Ghost
Well-known member
With the key = ON, pull an injector connector off and measure the pink wire to engine ground (not to the other terminal) for voltage. There should be system voltage.
Next test:
Turn key to RUN. Do you hear the fuel pump run for a few seconds then stop? (Should be YES). (If = No, you have other problems. Report back).
Flick key to START for just a second. Enough to turn the distributor perhaps 1/2 a revolution. Return key to RUN.
Do you again hear the fuel pump running for a few seconds then stop? (Must be YES).
If = NO, the ECM did not recieve reference pulses. Check the 4-pin connector at the rear of the distributor. If = Ok, Replace the Ignition Control Module. (ICM).
Note: Because you have spark (the engine fires on Ether), the pick-up coil in the distributor should be Ok. The portion of the ECM that controls the coil is also Ok. the portion that outputs the ref pulses to the ECM (pur/wht wire in the 4-pin) is NOT Ok. << I have only had ONE ICM fail in this manner in 25+ years of messing with numerous GM engines that use this ICM. But it happened to me ONCE. The fuel pump "does it run the second time" test I outlined above led me to the bad ICM in less than 10 minutes of trouble shooting.
Note II: I would check the resistance of the ignition pick-up coil, just to be sure: Unplug it from the ICM, measure Ohms between the white and green wires. Should be 500-1500 ohms to each other (my recollection is that about 850 ohms is typical), and infinite ohms to the distributor body. Wiggle the wires while checking, there should be no changes.
Next test:
Turn key to RUN. Do you hear the fuel pump run for a few seconds then stop? (Should be YES). (If = No, you have other problems. Report back).
Flick key to START for just a second. Enough to turn the distributor perhaps 1/2 a revolution. Return key to RUN.
Do you again hear the fuel pump running for a few seconds then stop? (Must be YES).
If = NO, the ECM did not recieve reference pulses. Check the 4-pin connector at the rear of the distributor. If = Ok, Replace the Ignition Control Module. (ICM).
Note: Because you have spark (the engine fires on Ether), the pick-up coil in the distributor should be Ok. The portion of the ECM that controls the coil is also Ok. the portion that outputs the ref pulses to the ECM (pur/wht wire in the 4-pin) is NOT Ok. << I have only had ONE ICM fail in this manner in 25+ years of messing with numerous GM engines that use this ICM. But it happened to me ONCE. The fuel pump "does it run the second time" test I outlined above led me to the bad ICM in less than 10 minutes of trouble shooting.
Note II: I would check the resistance of the ignition pick-up coil, just to be sure: Unplug it from the ICM, measure Ohms between the white and green wires. Should be 500-1500 ohms to each other (my recollection is that about 850 ohms is typical), and infinite ohms to the distributor body. Wiggle the wires while checking, there should be no changes.
DaveP's Ghost
Well-known member
You replaced the fuel pump. Have you installed a pressure gauge on the rail and CONFIRMED that you have at least 42 psi at the rail while cranking?
What part number / brand fuel pump did you install?
Did a counter person (pep boys, vato zone, etc) use 'VIN Z' as the guidance as to which fuel pump to give you? If you did, you have the wrong fuel pump. I once got a hell of a deal on a really nice Syclone that this happened to the guy. After three years of him trying to get it started, he gave up and fire-saled it. I knew what had happened before I finished reading his ad. Using "VIN Z" for a Syclone or Typhoon gives you the low-pressure TBI pump. The engine will not start on a TBI pump.
What part number / brand fuel pump did you install?
Did a counter person (pep boys, vato zone, etc) use 'VIN Z' as the guidance as to which fuel pump to give you? If you did, you have the wrong fuel pump. I once got a hell of a deal on a really nice Syclone that this happened to the guy. After three years of him trying to get it started, he gave up and fire-saled it. I knew what had happened before I finished reading his ad. Using "VIN Z" for a Syclone or Typhoon gives you the low-pressure TBI pump. The engine will not start on a TBI pump.
Wow great write up thank you so much for helping me out it was a Napa that gave me the pump but when I Originally purchased the sending unit it came with a 255””LPH fuel pump but that pump as well didn’t get the engine to run so I change it to the PNA1 had to do some custom fabrication for the sender which now fuel gauge reading low end I have about 5 gallons of fresh gas in it..... never actually confirmed 42psi, however the fuel rail nipple shoots gas out when depressed! I really wanna get her running even though I’m outta money and time.... do you think it’s the distributor??
DaveP's Ghost
Well-known member
Delphi makes both pumps. Either the part number or remembering the size of the hose nipple on the pump are the ways to tell them apart. 3/8" is the TBI pump, 5/16" is the PFI pump you need.
DaveP's Ghost
Well-known member
The fact that it fires on Ether eliminates a bunch of things such as basic timing, firing order, compression, and "spark" related components.
If you have power to the injectors, the fuel pressure is 42 psi while cranking, and the fuel pump run test passes, IT WILL START. << You don't have one of these. Figure out which one it is.
If you have power to the injectors, the fuel pressure is 42 psi while cranking, and the fuel pump run test passes, IT WILL START. << You don't have one of these. Figure out which one it is.
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Ok followed your directions step by step verified psi to the rail 45 psi, icm wires all checked out ok and even purchased new one just in case still cranks but no start, receiving power to injectors as well! When I first turn key to run check engine light comes in for split second and then goes away?? While cranking engine check gauges light starts flashing now also! And now I hear the IAC clicking back and forth while key is set to run, is this a problem? The IAC is brand new?
graham1524
Well-known member
I had a similar issue and it was ICM, could try and exchange it
DaveP's Ghost
Well-known member
Your ECM is NOT powering up. This is the very first thing I asked about. If the ECM is not powering up, the fuel-pump prime and run-again test will not pass either.
Check for power with the key in RUN on the pink/blk wire at the ECM.
Check both ECM fuses.
Check the two ground wires (one large black and one large tan) at the front of the intake manifold, LH side.
There are a group of ground wires on a bolt at the rear of the LH cyl head. One of them is blk/wht. The blk/wht are the ECM system grounds. Be sure these are connected.
Pay close attention to how these trouble-shooting charts are laid out, and follow them exactly, or you will be replacing good parts, and not fixing the problem.
Note in the upper left corner, by the "1", that the very first check for this chart is "Turn key to RUN. If Check Engine light is OFF, use Chart A-1".
(This chart A-3, is not the correct chart to use for "cranks but does not run" if there is no Check Engine Light in RUN).
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