Why do injectors keep failing?

[Dieselsj]

1987 Chevy R30. 7.4 TBI.

Had injector(s) fail back in October. Drove me crazy trying to figure out the issue. It got into a really bad lean surge just off idle and would never recover. After a whole lot of tuning and parts, replaced the injectors and the problem went away. Put about 3K miles on it.

About 2 months ago I started to get a CEL for a lean condition at light throttle cruise. Tried tuning it out but no amount of changes to the VE or any other settings would fix it. Issue started getting worse about 2 weeks ago where it started to stumble, and as of last weekend it is now back to the exact same condition that I had with the extreme lean surge. You can watch the O2 sensor voltage drop and INT climbs.

The injectors were brand new GM branded parts. I am getting them replaced under warranty.

What could be causing injectors to fail like this? Fuel filter is new. Fuel pressure is remaining constant at 13psi. I don't run any fuel additives. I pulled the injectors and the inlet screens were totally clean.

Anyone else have TBI injector issues?

[brian617]

Send the originals to MR. Injector for cleaning and flow testing. Maybe he'll be able to tell you what he finds. He's done good work for me.

[Dieselsj]

New injectors showed up today. Lean CEL gone. Stumble gone. Lean surge gone. Cracking the throttle I can see the increase in flow. The old ones didn't do that.