Necrodead

none of my oil injectors hold vacuum and there is air in the OMP lines. I believe this means my oil injectors are not working. However just buying new ones is a little pricy for me, getting all 4 new into canada would be over $450. I would also rather not block off the OMP, I premix anyways but I like having the OMP for peace of mind.

I understand they work off venturi to pull oil into the housings/LIM. But they just look like bolts with holes in them. is there a valve inside? can they be cleaned to maybe make them work again? there must be a reason they are close to $80 a pop.

or am I too worried about losing the OMP? should I just remove it and premix religiously?

1986 13b NA.

WondrousBread

How much vacuum do they hold? And are you testing them individually or with the little spider?

The manually only shows someone testing using their mouth, not a vacuum gauge. I'm guessing this means it only needs to hold a few psi of vacuum. Rlynchster bought some new ones though in this thread:

https://www.rx7club.com/2nd-gen-gene...ption-1154012/

And he said they hold around 25psi each. But then the design looks updated too, so they may hold more vacuum than the originals due to that.

Necrodead

I've been using that thread as a guide but I just don't have the money to fire the parts cannon right now. spider is holding vacuum but the injectors don't at all. like 0 vacuum at all. might as well be open tubes.

rlynchster

My opinion is that your observations are correct. "Air bubbles" in the oil lines are signs that the oil injectors are not functioning correctly.

I used a hand vacuum pump to simulate the FSM blow test in reverse and they acted as a check valve and held 25 inches of vacuum. . . Which equates to around 12 psi delta across the diaphragm.. . .All the new ones passed the check. . . .All the old ones failed and held no vacuum indicating a bad check valve.

I've never taken one apart but If I had to guess, there is a sealing diaphragm inside that acts as a check valve so that the engine pressure only "sucks" on that oil injector. .. When I say suck I mean the pressure is lower in the engine block relative to the upper intake. (through the spider)

When the check valve fails, the engine can have negative pressure on the oil line during acceleration, and positive pressure on the oil line during deceleration. . . . This fluctuation in pressure on the outlet side of the oil metering line causes the oil to separate from itself in the line and form air bubbles, or what I call, inclusions.

Imagine having a long small ID line filled with oil and capped on one side (omp side) and then oscillating from positive pressure to negative pressure over and over again over short time frames on the outlet side. . . Eventually the oil separates from itself and forms "bubbles" in the line as it moves from the OMP to the oil injector.

When the oil injectors fail, you can have air move back and forth from the engine block to the upper intake. Does this effect compression? Not sure.. . .What I do know is that my car idled better when I changed them and the oil in the line showed no inclusions/bubbles.

I would think if an oil injector failed due to crud buildup on the check valve diaphragm, then yes, they should be able to be cleaned with an ultrasonic cleaner and some degreaser in the water/solution being used. . . (maybe just let them sit in high proof rubbing alcohol?)..If they failed because of a worn and broken rubber diaphragm, then no cleaning will fix that. And as you know, there is no way to open them.

Use the hand vacuum pump to check after cleaning. Or blow on it like the FSM says.

professionalpyroman

I would second the trying to clean them. Let them soak in some isopropyl alcohol and then use an ultrasonic cleaner. If you can flush them out a few times, theres a fair chance they can be recovered. I would steer away from degreasers for the fact that there is a likelyhood of causing deposits inside the valve. You might also be able to soak them in kerosene.

Necrodead

A kind user from Texas has some old ones he's willing to sell me for a lot less than new. I'll take the old ones out and clean them anyways, I have an ultrasonic cleaner and lots of iso. hopefully I end up with 2 working of each.
Thanks for your thread rlynchster, its about the only place I found mention of oil injectors, and I also found my booster to be leaky. 👍