Cleaning 1974 K-Jet Injectors

ChupaChupChump

I’ve just about got my 1974 145 running, and I’m stumped on these clogged fuel injectors.

I’ve tried just about every workshop in town and no luck… any ideas?

ramrod

You could also purchase new injectors

It’s worth it I reckon, since they’re 50 years old now

ChupaChupChump

ramrod I’m considering it, but they seem pretty hard to find for a reasonable price. Saving these ones is the priority at the moment.

Roinik

There's an internal gauze filter. You can try holding the pintle open with some soft wire, soak in some aromatic based cleaner (Bunnos has some high Xylene content adhesive remover in the paint isle). Place the injector plus cleaner in an ultrasonic bath for a fair while. Then use compressed air and injector cleaner to push any crap out. Who knows, you might get lucky and settle spray pattern back. Ideally you'd use a diesel injector rig.

Have you tried an old Merc or Porsche workshop instead of an injector joint?

ChupaChupChump

Roinik That’s a great idea, I’ve ordered a small ultrasonic cleaner that should come in 2 days. I’m located in Armidale, NSW. Today I went around to a fair few shops and they were able to offer some alternative ideas (such as carby swapping it) but nothing super helpful. I’d like to keep the k-jet, it seems pretty hard to find injectors though.

John_Fraser

I've had good luck cleaning, unclogging, and testing my '81 242 B21F kjet system by the following:

Add a fuel injection cleaner such as BG 44K or Chevron Techron to the tank then add fuel to mix it up.

Dismount the injectors but leave connected and slip some clear tubing over each. Install a clear plastic bottle (soda bottle works) on each tube.

Remove the large plastic intake air duct at the kjet air meter.

Jumper power to the fuel pump fuse and raise the disk in the kjet airmeter to control the fuel flow.

Observer the injectors' spray in the tubing and then let the system soak as needed. Pattern should be cone shaped with no gaps or separate streams.

You will need the Volvo Wiring Diagrams manual for your year and model, available for download at https://ozvolvo.org/archive.

Also download from the internet, the Bosch K-jetronic Fuel Injection Manual

https://vdocuments.net/bosch-k-jetronic-fuel-injection-manual.html

ChupaChupChump

John_Fraser this is great news!

I’ve already put the fuel pump on a switch so this will be a great test. I’ve ordered a small ultrasonic cleaner. Do you have any recommendations for what to clean them with in an ultrasonic cleaner?

John_Fraser

ChupaChupChump

I don't have any experience with ultrasonic cleaning. However, the valve at the tip of the injectors may have to be open or at least leaking for the fluid to get in there. If they leak this drains the fuel system into the cylinders and can make for hard starting and initial rough running. See the Bosch KJet book linked above for a full explanation.

ChupaChupChump

I ran the pump the other day with injector lines going into a jerry can and got some white floaters sitting at the bottom. The flow was alright after about 10 minutes. I’ve since dropped the fuel that was in it and put it in my lawnmower instead. I’ve ordered a bulk pack of in-line fuel filters and I’ll put some 95 in with more injector cleaner and let you know how it goes. My small ultrasonic cleaner should be coming tomorrow too, so hopefully I can sort out these injectors.

ChupaChupChump

John_Fraser What soft wire did you use? I’m afraid of damaging them. I’ve had them in and out of a cheap ultrasonic cleaner and soaking in different injector cleaners to try and get the best result in my next attempt.

John_Fraser

ChupaChupChump

See page 19 in the downloadable manual.

Roinik

I used copper wire when doing 240 ones.

ChupaChupChump

Roinik how did you get enough force to open them?

Nico142

Used my fingernail to lift the seal / plunger then used small copper wire to hold them open.