Astro 88 won't Start HELP!!!!!
pleeboo
03-23-2006, 08:26 PM
I have an 88 astro with fuel injectors that are not working replaced e.c.m., dist module, pick up coil, tested every single wires ,ground wires .got tones of fuel to carb got live feed to one wire to injectors got negative pulse to other injectors wire .only way i get injectors to work is direct from battery
Blue Bowtie
03-25-2006, 11:32 AM
I have an 88 astro with fuel injectors that are not working...
It seems that the injectors ARE working, since you can get them to operate by providing external power. (See below)
replaced e.c.m., dist module, pick up coil, tested every single wires ,ground wires.
It was good that you tested the wires. Too bad you replaced all those parts before performing any diagnotics. At least you should be able to rely on them. Did you also bother to replace the fuel filter?
got tones of fuel to carb got live feed to one wire to injectors got negative pulse to other injectors wire .
You really have fuel to the TBI220, since you don't have a "carb". And if you could, quantify "tons of fuel" for us. Lots of flow doesn't mean much if the pressure is inadequate. The TBI is supposed to operate at 11-13 PSIG. It needs at least 10 PSIG. I've seen them run as low as 7, but not very well. You need to verify adequate fuel pressure. Since there is no test fitting (Schrader valve) on the TBI systems, you'll need a test adapter with your pressure gauge.
only way i get injectors to work is direct from battery
This means the injectors actually DO operate. It doesn't mean that they are operating correctly, however. They could be weak, or propagation delays could be preventing them from delivering fuel at the normal ECM firing timings, although the MAXI injectors are not really commonly known for this type of failure.
The first thing to do is to verify correct fuel pressure. After that, ascertain that the +12VDC supply to the injectors is present. I understand that you have "tested all the wiring", but you need to monitor the +12V while the injectors are fired. If the voltage drops when you ground the negative side of the injector, the supply has a poor connection somewhere. If the voltage maintains, you can consider the power source to be adequate.
Leave the electrical connector on the injector, and back-probe it to connect to the wires. Insert one jumper wire on each terninal. Measure the voltage to a good ground. The positive voltage source shoudl not drop more than 0.5V when you manually ground the negative side of the injector. Don't worry about damaging the ECM, since you are only providing a parallel path to ground for the injector. The ECM does the same thing, and is at the same polarity. If you can get the injectors to operate via this method, they are fine. You can connect a test light in parallel with the injector while cranking the engine to be certain the ECM is completing the ground circuit and firing the injector.
It seems that the injectors ARE working, since you can get them to operate by providing external power. (See below)
replaced e.c.m., dist module, pick up coil, tested every single wires ,ground wires.
It was good that you tested the wires. Too bad you replaced all those parts before performing any diagnotics. At least you should be able to rely on them. Did you also bother to replace the fuel filter?
got tones of fuel to carb got live feed to one wire to injectors got negative pulse to other injectors wire .
You really have fuel to the TBI220, since you don't have a "carb". And if you could, quantify "tons of fuel" for us. Lots of flow doesn't mean much if the pressure is inadequate. The TBI is supposed to operate at 11-13 PSIG. It needs at least 10 PSIG. I've seen them run as low as 7, but not very well. You need to verify adequate fuel pressure. Since there is no test fitting (Schrader valve) on the TBI systems, you'll need a test adapter with your pressure gauge.
only way i get injectors to work is direct from battery
This means the injectors actually DO operate. It doesn't mean that they are operating correctly, however. They could be weak, or propagation delays could be preventing them from delivering fuel at the normal ECM firing timings, although the MAXI injectors are not really commonly known for this type of failure.
The first thing to do is to verify correct fuel pressure. After that, ascertain that the +12VDC supply to the injectors is present. I understand that you have "tested all the wiring", but you need to monitor the +12V while the injectors are fired. If the voltage drops when you ground the negative side of the injector, the supply has a poor connection somewhere. If the voltage maintains, you can consider the power source to be adequate.
Leave the electrical connector on the injector, and back-probe it to connect to the wires. Insert one jumper wire on each terninal. Measure the voltage to a good ground. The positive voltage source shoudl not drop more than 0.5V when you manually ground the negative side of the injector. Don't worry about damaging the ECM, since you are only providing a parallel path to ground for the injector. The ECM does the same thing, and is at the same polarity. If you can get the injectors to operate via this method, they are fine. You can connect a test light in parallel with the injector while cranking the engine to be certain the ECM is completing the ground circuit and firing the injector.
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