So i recently discovered 2 of 4 fuel injectors are working, tested them for spark. All 4 of them are getting spark. Took a stethoscope to listen for the fuel passing though, only 2 of them were getting fuel. Is there anyways to clean or fix these ? Thank you.

 

did you do the click test? a 89 740 should have OBD, put it in fuel system diagnostic mode 3 (see the 7xx FAQ on VCOA or whatever for instructions on this) and it will cycle the injectors with the engine off so you can stethoscope them and hear them clicking. if they aren't clicking, the valve inside must be stuck.

take them out, clean the outsides and tips with brake cleaner. use a brush to really clean the tips, blast them with compressed air, brake cleaner, compressed air, brake cleaner, repeat til clean. the one time I cleaned EFI injectors that was as far as I had to go, but if they are really gummed up, maybe soaking overnight in a covered can of solvent would help, then repeat the above brush/air/solvent thing.

 

Nice, thank you so much, in terms of solvent what kind would you suggest?

 

brake cleaner is good stuff for this kind of thing. gotta be something that won't damage the plastic and rubber bits or the wiring.

 

What you can also do is remove fuel rail and pull the injectors out one at a time. Slip a suitably sized hose over the fuel rail end of the injector and fill hose with solvent of your choice. Then use the diagnostics to cycle the injectors. It can help free up badly stuck injectors, but you'll need a good drive afterwards to get fuel flowing through them properly.
Good solvents are mineral turpentine, methylated spirits (or E85 if it's available near you) and similar solvents. If you are keen, you can slip hoses over all the injectors, fill with solvent and let sit overnight.