2.5 Throttle Body Injector Options

[89JeepYJ]

Hey guys, looking for some direction here.

I’ve got an ’89 YJ 2.5L TBI and I’m chasing what seems like a bad injector. I replaced the O-rings thinking it was leaking, but it’s still flooding the motor pretty badly.

RockAuto has a “return & rebuild” option for around $40—has anyone here actually used that service? Worth it, or am I better off putting that money toward a replacement?

Trying to keep this budget-friendly if possible. New injectors are pretty pricey, so I’ve been looking into alternatives.

I’ve read that these Jeep TBI injectors are similar to GM-style units from the late 80s/early 90s, but not exact matches due to flow rate differences . That said, has anyone successfully run a junkyard injector from another vehicle? If so, what vehicles should I be looking for?

Also open to any other ideas—before I throw more parts at it.





Appreciate any help

 

[Gilaguy23]

All I can offer is the FI kit from Howell uses a Chevy 4.3 TBI set up.

 

[jpjeep26uk]

My 2 cents worth:
1, Take the injector out of the TBI.
2. Take a 9v battery and hook two wires to it.
3. Touch the two prongs on the injector with the two wires from the battery.
4. The injector should click each time you touch the wires to it.
5. If it clicks - it's working.

Second thing to try.
1. buy a NOID lamp - just a few dollars for the Chrysler one.
2. connect it to the plug that normally connects on top of the injector when its bolted in. ( on your picture its the two pale yellow sockets facing upwards)
3. turn the car over as if to start it.
4. NOID lamp should flicker very quickly.
5. If it flickers then the power from the ECU is good and therefore when the socket is connected to the injector you know the ECU is 'firing' it and petrol is squirting out into the Thottle Body.
6. No flicker = bad news - May need to test the ECU to ensure the signal is leaving it to the injector. Terminal 21 is the one signalling

the Injector.
( technically FYI, it's on all the time and the ECU provides a negative signal to 'fire' pulses at it not the other way around)

third thing to try
Your injector may not be getting fuel at the right pressure which i think should be about 30psi - yes....30psi.....stick a fuel pressure gauge on the fuel inlet pipe coming into the TBI - the shiny brass / steel metal hose nearest you from the side of the engine bay.
Any less pressure and you wont be able to start the car.
Check fuel filter or replace anyway.

hope that helps...

A noid light is a specialized diagnostic tool used to test automotive fuel injector circuits and idle air control valves for power and triggering signals from the ECU. By plugging into the wiring harness, the light flashes to confirm if the injector is receiving a signal, helping identify faulty wiring or computer issues, often used for troubleshooting misfires.

You need this GM one below with the two brass prongs.