Due to occasional misfire or unevenness at idle, I had reason to suspect the injectors were less than perfect. I wanted to test them rather than just a shotgun replacement approach, because if one or more were bad, I wanted to understand why. I didn't find any affordable test/clean devices that would work off the car, and I wanted to keep it cheap.

I bought a wall-mount plastic water filter casing - bottom container screws off the top, which has NPT ports for I/O. I got a pair of NPT/barb adapters for 3/8" rubber hose, stuck a short length of that on the inlet, with a valve carved off a bicycle tube crammed in. Outlet had a longer length of tubing, with another length of smaller diameter tube leading from theinside of the port to the bottom of the filter container. Into the other end of the outlet tubing I inserted the fuel distributor end of an injector line from the car. All secured with hose clamps. A bicycle pump with integral gauge used to build and monitor pressure. Total cost for hardware I had to acquire about $30. Only useful item I elected to forgo was any sort of filter.

For solvent I first used Coleman fuel (naptha), mostly to clean the lines, then test the idea. It worked, but no sign of any cleaning action. I considered 'parts cleaner', but the label warned of methylene chloride, a plastic solvent, and I decided against. I finally settled on a bottle of Techron injector cleaner. Procedure: pour solvent into container, screw on top. Connect injector to fitting, and let hang in glass jar. Pump, checking as pressure rises. Observe spray when check valve opens, and continue pumping as necessary until injector 'clean'. Disconnect pump and depressurize valve before jar overflows. Disconnect injector. I reused the solvent, checking for contamination as I went, testing in order 1 - 4.

Injectors 1 & 2 produced a lot of flow, and 'sang' loudly. I presume they are ok, but I don't know what to expect a proper spray pattern to look like. Injector #4 sang too, but less enthusiastically, and the pattern looked less even. The #3 was an issue. It seemed to have a restriction. It had way less flow than the others, did not sing at all, and the pattern was lousy. I even cocked the pintel open with a piece of toothpick and backflushed it, but it did not improve. Never in the whole process did it seem I was able to clean anything from the injectors, and I was even a bit worried I might be mucking them up inadvertently. However, I was satisfied that as a test, the system had worked.

I installed new seals (the old ones were hard - had to be cut off) and sealed everything back up. Car seems to run as before, so far, and I have ordered 4 new injectors.

Steve

__________________
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7