One injector not working on '90 g30 TBI
 

One injector not working and can't figure out why. Have been having issues with injectors. Was running good for awhile but then started running ruff. Found one injector not working. Checked injector and it works. Getting proper fuel. Checked wiring all way to ECM. No problems that I have found. Getting tired of working on this thing. Work rig so can't be down long. Acts like the ECM is not grounding injector . At wits end.

what happens when you swap the injectors?

I find that when components work intermitantly we get fooled into thinking they are good. Since the TBI unit is 28years old and you said you need dependability, just replace the injectors or get a new TBI unit.

SD

I have been having issues lately with this system. I have been searching the internet for the last couple weeks looking at several ways to repair my van. I have gone over and replaced a few parts in hopes of finding problem. Both injectors were working (finally) yesterday. Was running a little high rpm at idle. Found vacuum leak. Then restarted and sounded ruff at idle. Looked to see only one injector was firing. Rechecked wiring and found no breaks or anything. A friend has been telling me that there is a short in the system some where but have yet to find it. But it ran fine yesterday for awhile. My Dad was a mechanic so I know about the how they work. But when you put more electronics in the mix if just gets more confusing.

Here is my 2 cents
if its electrical and its intermediate that will be the hardest to find and fix.
I know scoping the injectors would be the best solution for real time diagnostices
but if you dont own one then it become expensive to have a shop do it.
I like the challenges of electrical issues... I have fixed many of them
But I promise you we are only as good as the tools we use....

28 year old electronics, at that.

One injector is all the works at idle. The secondary injector is the cold start/secondary injector that kicks on like the secondary on a carb. When you floor it or apply deeper throttle pressure, or starting up.
If one is working but appears to be dribbling instead of spraying, it could be dirty. That is why i suggested swapping them. The secondary injector gets more intermittent use and could be in better shape.

So, what you're saying is that they're the same part, just in different positions(primary/secondary)?

yes.....

Testing the injectors.. I thought this was cool Never had I seen this before.. lol