1981-1983 Imperial Fuel Injector Cleaning and Testing

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It is really easy to clean out the fuel-injector nozzles, as the whole nozzle assembly comes off with two screws and one fuel fitting. I have found it very common that one or the other nozzles are not spraying a good stream. I just take the assembly out, pull the top pressure valve assembly off the nozzle weldment (two more screws), and put the carburetor cleaner squirt can plastic straw right into the fuel passage and squirt. You can see easily whether or not all of the nozzles are clear, and if not, you can push the cleaner in reverse back through the tubing until you flush the offending particle of crud out. The orifices are really small, it does not take much to plug one up, even a partial obstruction will goof up the pattern. If you want to observe the flow, you can temporarily run a 12-volt wire to the control fuel pump on the HSA. Pull the two-wire plug off the pump motor, and check with your VOM to see which one is grounded. The other one is driven by the electronics to various voltages in accordance with the CCC's required fuel flow. If you disconnect the pump harness, you can do this with no danger of feeding voltage back into the fuel pump driver, which might be hard on things. One side of the pump harness is ground, the other is hot, so take two clip leads and connect the appropriate terminals for just a second, while you look at the spray stream. This pumps a lot of fuel in a hurry, so don't linger at the task.

Dick Benjamin


I'm not sure we ever discussed this issue of when 4 nozzles are supposed to squirt, and when 8 nozzles. As you realized I'm sure, when you cleaned out the nozzle assembly, this is controlled by the level of pressure being produced by the Control Fuel Pump. The two valve assemblies in the nozzle have different threshold settings. I believe the lower valve is set to open around 20 PSI, and the higher one much higher, like 50 PSI. during cranking, you were only asking for fast idle RPM, so the lower pressure was the only one reached. Situation normal.

Dick Benjamin

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