87 GMC Sierra R3500 7.4L TBI vacuum diagram

[DieselSJ]

Originally Posted by Captain J

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For the speedo sensor is it behind the cluster? Do you’ve a picture?

So what I should do to fix Code 44?

I did order the electrical connectors, and I’ve a rebuilt kit, and I’ll work on it.

I’ll check the clicking to verify your diagnostic.
When you say ”if it still clicks when you have no fuel spraying then problem is with supply” what you mean?
Thanks

If the injector is clicking, it should be spraying fuel. If it is clicking and no fuel is coming out, then it means the fuel supply is plugged somewhere or air is getting into the system.

[Captain J]

Originally Posted by DieselSJ

Code 24 is speed sensor malfunction. The sensor is built into the speedometer. You should be able to see (or feel) the wires coming off the back of the speedometer and make sure it is plugged in. If sensor is bad, then you have to replace the speedo.

Code 44 is lean. I chased lean codes for a while on mine. I had bad wiring to the O2 sensor, bad fuel pumps, plugged filter.

Watched the video with your injectors and they should not be going on and off like that - you want a continual steady spray. I'd probably start with replacing the electrical connectors on the tops because those look bad. There are also small filters on the injectors themselves. Get a rebuild kit and pull the injectors out of the pods and replace those screens. I can't tell if the injector just isn't firing or if you are getting air in your fuel. Use a stethoscope to listen to the injectors and listen for consistent clicking - if it still clicks when you have no fuel spraying then problem is with supply. If it stops clicking intermittently then you have an injector or wiring issue.

I replaced the electrical connectors with new ones, (still waiting for rebuild kit)
I used a hose to listen to the injectors, they’re clicking consistently only when spraying fuel,
However the spraying pattern still the same.