No start
#23
10-25-2022, 12:53 PM
Well I put the upper intake back on with everything hooked up but it is doing the same old thing. I believe when I turn the ignition on the injector gives fuel and runs for a few seconds. Acts like the injector is not getting a signal to keep it running. I have read where cam sensor could be faulty. What do you think
#26
10-26-2022, 11:40 AM
Let’s make sure I understand everything right.
You had low pump pressure but you have not seen a leak down pressure below 55 psi since the new pump AND the tightening of the fuel line?
Every time you have tested the harness for ground side pulses, the test passes, including when using a noid light and the 6 different pink wires as the source of power matched up with the appropriate ground side control wire for the light?
You removed the spider to check for fuel spray during cranking, saw none but at one point they did start spraying but not in reaction to any changes, IOW you have a random spider firing problem?
Your injector coil resistance values are below the GM spec but you also don’t have a GM spider so I am not sure if this tells us anything useful, if the values are all within 10% of each other then that’s good.
If the spider has sprayed and not sprayed fuel during cranking randomly without making any changes then we have not found the problem yet. There is an easier way to check for proper injector spray volume without removing the upper intake by using a pulse generator (or appropriate scanner) and a fuel gauge. I don’t think this is a cam sensor problem. You get pulses at every test but you don’t get spray volume at every test. I think you will get injector pulses even with the cam sensor unplugged. This points to the spider assembly even if it’s a new replacement. Let’s make sure that the noid light is putting the same load on the circuit that you injectors coils are. What is the dc resistance of the noid light? Is it near the 8 ohms of these injectors? If we put the same load on the circuit that the injector coil does and you test all 6 individual injector circuits (proper pink wire to ground control wire) for pulses and you always have pulses AND sometimes you get no spray volume then it’s either the spider or the spider connector.
George
You had low pump pressure but you have not seen a leak down pressure below 55 psi since the new pump AND the tightening of the fuel line?
Every time you have tested the harness for ground side pulses, the test passes, including when using a noid light and the 6 different pink wires as the source of power matched up with the appropriate ground side control wire for the light?
You removed the spider to check for fuel spray during cranking, saw none but at one point they did start spraying but not in reaction to any changes, IOW you have a random spider firing problem?
Your injector coil resistance values are below the GM spec but you also don’t have a GM spider so I am not sure if this tells us anything useful, if the values are all within 10% of each other then that’s good.
If the spider has sprayed and not sprayed fuel during cranking randomly without making any changes then we have not found the problem yet. There is an easier way to check for proper injector spray volume without removing the upper intake by using a pulse generator (or appropriate scanner) and a fuel gauge. I don’t think this is a cam sensor problem. You get pulses at every test but you don’t get spray volume at every test. I think you will get injector pulses even with the cam sensor unplugged. This points to the spider assembly even if it’s a new replacement. Let’s make sure that the noid light is putting the same load on the circuit that you injectors coils are. What is the dc resistance of the noid light? Is it near the 8 ohms of these injectors? If we put the same load on the circuit that the injector coil does and you test all 6 individual injector circuits (proper pink wire to ground control wire) for pulses and you always have pulses AND sometimes you get no spray volume then it’s either the spider or the spider connector.
George
Last edited by GeorgeLG; 10-26-2022 at 11:43 AM.
#27
11-20-2022, 05:24 PM
I took a break from working on this for awhile. After rereading our text I rechecked everything. You said the ohms should be at least 8. I am getting 5 ohms. I recheck the grounds and they looked good, I did take them off and cleaned them real good. Could the computer be bad? Also the first spider assembly I put on was an ACDelco, second was a delphi. Thanks for hanging in with me. Papajim
#28
11-21-2022, 04:12 PM
The engine computer can always be bad but it is rare. I have seen dozens replaced and only a few fixed the problem. On older trucks like this it is more likely to be the wiring.
If the fuel pressure is at 55psi after 10 min after key on engine off,the injector noid lights flash smoothly and it still runs good with starter fluid then I would check the injector function with a pulse box and a fuel gauge.
I dont know if your injector coils at 5 ohms are a problem. Its below the spec but those are good spider brands and I dont know how much the spec may have changed in 20 years. Are they consistent?
George
If the fuel pressure is at 55psi after 10 min after key on engine off,the injector noid lights flash smoothly and it still runs good with starter fluid then I would check the injector function with a pulse box and a fuel gauge.
I dont know if your injector coils at 5 ohms are a problem. Its below the spec but those are good spider brands and I dont know how much the spec may have changed in 20 years. Are they consistent?
George
#30
11-28-2022, 12:01 PM
I don't know what to make of the 5 ohm reading on the injectors. The spec was written 20 years ago for the OEM AC Delco injectors of the day. How consistent is the reading across all 6 injectors? Do you have the old spider to compare? Again, the ultimate test is firing each injector with a metered pulse and checking the fuel pressure drop which indicates the amount of fuel delivered.
George
George