Fuel Injector Cleaning question

Hey all,

Many years ago (2007, to be exact) I bought a fuel injector cleaning "kit", which consisted of a hose that connected a can of injector cleaner to the schrader valve on the fuel rail. Basically allows me to do the "run the engine off the injector cleaner" level of cleaning service that the dealer would do.

I'm considering pulling it out in the very near future, but when I tried to look up the thread on where it was discussed, I realized that the others using this sort of thing 97+ owners who had a "returnless" fuel system.

My old '92, being early HO, has a return line and it occurred to me that I might have to do something to prevent some of the cleaner from being sent back to the tank via the return line - is it as simple as removing the vacuum line from the regulator on the fuel rail?

It's been so long since I used this thing, I honestly can't remember whether there was anything I had to do with the regulator or not. I'm going to check my FSM and the instructions in the kit (yes I still have those) to see if I can puzzle it out from either of them, but figured I'd check here as well as a backup...


Rob

You typically unplug or pull the fuse for the fuel pump. If the can is at a higher pressure than the FPR without the vac line attached, then you probably need to pinch off the return line.

Got a picture of the setup? Just curious if it's a disposal spray can, or a nice setup where you pour in the cleaner/fuel and connect shop air for the pressure.

Pull the injectors and send to an injector cleaning service. A good injector cleaning service will use an ultrasonic cleaner which can't be duplicated by any on-vehicle cleaning method. As a bonus, an injector cleaning service will tell you if any of your injectors beyond being cleaned (i.e., have a permanent leak).

For the price of sending them out, you could contact one of the folks here selling refurbished 4-hole Bosch injectors.

The kit I have is basically just a hose - one end screws onto the schrader valve on the fuel rail, the other end attaches to a sort of aerosol can (disposable) containing the cleaner (said can does NOT have the typical spray nozzle) and has a twist valve of some sort that opens the can and regulates . Have not had a chance to pull the thing out since my last post, but I think it works like those "saddle valves" for tapping a copper pipe to plumb in the ice maker in a freezer? Will try to get a pic tonight of what I have, I think I know where it is and can get to it easy. Might even actually be from 3M - have to check the instructions when I get my hands on it later.

I know about pulling the fuel pump relay fuse, remember doing that the last time. What I don't remember is what (if anything) to do about the vacuum regulator. Not sure if my return line is something that can be pinched off - been a while since I looked, but the lines to the rail may be semi-rigid plastic that probably wouldn't tolerate pinching.

I already have Bosch 4-hole injectors (the 703s, if memory serves) - put them in something like about 10 years back or so. Not interested in buying another set.

As for finding a service/shipping them out? I was going to use the cleaner kit over the weekend before doing an oil change, as I'm due for that and the NAC RocktoberFest event is the following weekend. Figured if I doing that, the injector clean would be better to be done before the oil change, rather than maybe dump contaminants into the fresh stuff. Wouldn't be time to ship out/get back, and don't have the time to swap the OEM ones back in (assuming they'd be functional after a decade in a ziploc bag). Don't really want to put the old ones back anyway.

i Just stumbled on the NAPA Know-How blog, and from what I read on that, it sounds like more vacuum means less fuel returns to the tank, so maybe I need to put my knock-off Mityvac on the regulator and pull vac on it to "shut off" the return line? https://knowhow.napaonline.com/what-is-a-fuel-pressure-regulator/

Ok, I found the kit this morning, and in the instructions it stated to disconnect and cap off the vacuum line to the regulator.

I got a pic of kit itself, and then a pic of the two cans of cleaner I still have. Here are links to the two in my Google Photos area (don't know how to make them appear right in the post using Google Photos):

The kit:
https://photos.app.goo.gl/rG9B4xaCmYnR7BYv9
(not pictured: an o-ring included to help sealing against the rail, and a pack of 5 driver bits included as a "free gift")


The cleaner:
https://photos.app.goo.gl/1Gfjp4QBJhBwctAA9

No shop air connection needed, the can is pressurized. the valve end of the hose in the first pic attaches to the can and you manually adjust the valve to maintain about 35psi.