Okay, on the primary and secondary injectors, there are diffusers that fit down into the LIM for the secondary and down into the center iron for the primary. Then, from what I can tell, you have a smaller diameter injector insulator fit down on top of the secondary diffusers, and a larger diameter insulator for the primaries. Then, your rails bolt down. Now, what could be the result of forgetting the larger diameter insulator on the primaries??? I have been having some serious fuel issues as seen in this thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/about-throw-fd-away-676642/

As I was going through extra parts, I noticed the larger diameter primary insulators still sealed in their packaging. I remembered that when I removed the primary rail, there were just the air bleed sockets and no insulators....would this somehow allow the injector to leak fuel or create some sort of sealing issue?

Here is a picture of the diffusers with their insulators: Primary diffuser and insulator are on the left and secondary are on the right. I did NOT have the primary insulator installed when I pulled the injector rail off.




Trev

 

I would just go ahead and recondition the entire fuel system. I recommend it when swapping engines unless your components from the previous engine are practically brand new. Here's a good thread on all the parts:

https://www.rx7club.com/3rd-gen-archives-73/injector-removal-reconditioning-replacement-232603/

I don't believe the insulator would cause the problems you were seeing.

 

I figure that it could still allow fuel to leak into the motor in the primaries. Either way, they were completely missing when I pulled the rail out, so I am installing new ones.

Trev

 

Naw, those are more to keep fuel fumes from emitting from the system and to provide a good seal to the block. The injector o-rings keeps the fuel from the rail leaking past the injectors.

 

i see. It is interesting that I never smelled anything with both primary insulators missing.

Trev

 

I've seen a lot of people not use them (not all of them intentionally) and not have issues.

 

gotcha. well, I am replacing them and getting the injectors re-checked at RC (KGparts did them 10 miles ago)

Trev

 

Here is another thought. If I were missing the insulators, I know they create a seal...is it possible that could be a vacuum leak source?

Trev

 

Yes, they are there to prevent vacuum and boost leaks. Additionally, If you leave them out you will also bleed off the primary port boost reference signal that is used to control the FPR (fuel pressure regulator).

 

So what you are saying in short is this could be the cause of my stumbling under acceleration and bouncing back and forth vac readings?

Trev

 

Yes Trev, if you don't install all the parts things tend to not work as well. Those are the source of your 1-low vacuum, 2-stumble, and 3-low fuel pressure which I'm sure you have while driving if you ever hooked up that FPR where you could see it.

Hope you aren't wasting any money sending injectors off for servicing again. Injectors are NOT your problem. If a primary was stuck shut the car would be running on one rotor only. Your doesn't do that. It isn't injector related.

 

Jon, how's it going over there? Yeah, I am pretty much an idiot. No, I am not getting them cleaned again. I am glad I found the source of the problem however I have new parts on the way, so should be up and running Wednesday!

Trev

 

I will keep you all updated as soon as the parts come in and I can get this put back together. I can't believe I was such an idiot....i am pretty sure this will solve the issue...

Trev

 

Joe, you're completely right! There are some people that may forget to put the grommets on the rail and install them into the block. If you leave the grommets in the block and try to put the rail back in it will likely come out of place, rip, and or get in the way of the injector spray pattern... I'VE SEEN THIS BEFORE!!!!

 

I see...so recommendation is to install the insulators on the rail, that put them in the block...i wondered about this...any oil need to be applied to these?

Trev

 

oil will help, good luck I hope this fixes it

 

Oil can help though I dont use it. The rail should just slip right in. Just be very very careful around those OMP lines!!!

 

the OMP lines are new and SS, so now issues there. Again, it is recommended to fit the insulators ON the rail before you install the rail? I could see that making it easier

Trev

 

^ A: I makes it easier B: It makes sure it doesn't slip crooked into the Iron bore...

 

Well, unfortunately, the missing insulators were not the issue. Still having the same problems! Just an update for future searches..

 

I figured as much. You would have had a slight vacuum/boost leak, if anything.

Also, there is nothing wrong with installing the grommets in the intermediate iron first, then inserting the rail and the injectors into the iron. I've done this many times over the years with no problems, and recently verified that the good men over at rx7.com do it the same way, have been since the FD came out. If anything, the grommets can tear when the primary rail is removed from the motor.

One of the more common mistakes I've seen that can damage the grommets is neglecting to install the thin plastic spacer that goes under the driver's side portion of the primary rail. if that spacer is left out, the entire rail becomes canted, which can lead to problems with the grommets.