Another episode in my never-ending saga to conquer boost/vacuum leaks (I think this is leak #6)... this is a 1988 Rx-7 Turbo II doing a fuel system upgrade with stainless steel lines.

I've got the KG Parts secondary fuel rail and Bosch 1680 cc injectors. They fit fine in the rail and don't leak fuel from the top. The problem is that the Bosch injectors seem to be leaking air from the manifold when I pressure test the intake with an air compressor. I initially installed them in the injector holes as they came. The Bosch injectors have a blue o-ring, then an orange spacer, and finally a yellow pintle cap (with a lip around it) at the bottom. The stock injectors just have a lower grommet with no o-ring.

When I discovered air leaking out I pulled the injectors and searched on the forums here. I didn't seem to find many threads about actually installing them, and no conclusive "how to" to make them fit without a vacuum leak. Somebody suggested using the stock pintle caps on there. So I pulled off the yellow Bosch pintle caps (and damaged them in the process. ****.), the blue o-ring, and the orange spacer. I installed the grommet and pintle cap from the stock Denso injectors. They slide on there but don't fit snugly unfortunately--maybe I have slightly different 1680's ? I installed the injectors anyway, verified they weren't leaking fuel (used the check connector), and then pressure tested the intake and they STILL leak air!

Now what do I do??? The original pintle cap, o-ring, and spacer on each Bosch injector are not in reusable condition unfortunately. I've about had it with these things. I wish I could pay someone to prep them for me so they just fit right in with no bullshit.

 

I keep a short length of 10mm (I.D.) silicone vacuum hose just for this...

I just measure and cut a short piece just for this.
Pull all the pintle caps, as you don't need them.

This is the quick & easy way to take care of this "problem".


-Ted

 

wait, so remove the pintle caps. I got that part. Now what's this about hose? You want me to place vacuum hose in the injector holes and then place the injectors in the hose? And they will still spray properly?

What about the stock grommets? take those out too?

 

Yeah, the short piece of 10mm silicone hose replaced the lower grommet.
It allows the fuel injector to seal against the engine block.

If we're talking Bosch 1600's, remove the o-ring and plastic pintle cap.
The tip of the fuel injector is not in the moving airstream, so you don't need to worry about debris damaging the tip of the fuel injector.
Cut the silicone hose just enough to allow the fuel injector to seal well.
This might take a few tries to get this right.
If you have a stock lower grommet, cut the silicone hose just a little taller than the stock piece.


-Ted

 

well damn. I don't have any 10mm silicone hose. Guess I gotta order it, as there doesn't seem to be any standard sized equivalent to that which would be available at a typical parts store. You use 10mm hose techniques hose?

 

Yeah, I use whatever I have laying around.
Hose Techniques is one of the more popular brands.


-Ted

 

Cool tip.

 

**** this. I am buying some rubber **** at the store... closest to 10mm I can find. Because of the outrageous shipping costs and minimum order size, it's going to cost me $28 from hose techniques when all I really need is 6" of the stuff.

what size should I try? 5/16 ? do they even sell like 11/32?

EDIT: So if I still have the stock grommet, do I want the Bosch injector to have the grommet installed on it and then have the grommet sit up against the hose? Or did you just mention the stock grommet to give me an idea of how long to cut the hose?

 

Eh I too made the mistake of getting KG rails
but anyways I had to have some aluminum inserts made at a machine shop.
just find a hose that can slip on the bottom of the injector and fit into injector holes
on the manifold/block...you may have to shave the hose a bit to fit

took me hours and $$$ to get the KG crap rails stop leaking and seal
especially at the boost /CFM levels I run

 

NAPA will have your hose.

 

^^ the biggest mistake I ever made in this turbo upgrade process was buying the rx7store extreme fuel system kit, which included the KG rail. The kit was a piece of crap. It had no instructions (such as how to avoid leaks like this), and it was just a bunch of parts thrown into a box. When I called them the person I spoke to was very condescending to me. I should have just put the whole thing together myself.

I think the KG rails are much better for FD's. FD's don't use top feed injectors anyway, so they need them.

 

easiest way for me was to grind down the lip on the pintle cap, cut off the orange spacer, keep the gromet. Then put on the stock rubber grommet. This has worked perfectly for me.

 

Try 3/8" hose...
3/8" = 9.5mm
Try to get hose that doesn't have that reinforce braid in it.
The braid just causes it to leak.
If you can find 3/8" hose that's solid and fuel resistant, then that'll work.


-Ted

 

I attempted to grind down the lip on the pintle cap with a bench grinder thing and that failed miserably, and now I don't have another cap for a second attempt.

A friend of mine claims he has some 10mm hose techniques hose lying around so I will probably try to hit that up first. I need a break from the car. I have spent probably 20 hours from friday to sunday on it. I guess I'm a pro at installing and removing a UIM now though.

 

http://www.rx7.com/store/rx7/1600ccPintle.html

Update: According to Banzai Racing, apparently the s5 pintle cap (not the s4, which is what I used and didn't fit snugly) will fit on the Bosch injector and allow you to use the stock grommet. I am going to order s5 pintle caps from mazdatrix. So that's another option besides cutting fuel hose.

 

arghx: their was a link posted awhile back showing how to Install the Bosch 1680cc FI's Into their FC secondaries. It was a step-by-step process and was well Illustrated.

I've searched but I was unable to find It. Would anyone remember this link?

 

I searched and didn't find it either. If anyone is searching around and finds this thread though, I ordered the s5 pintle cap and new lower injector grommets (same for either series). They are $2 each for the pintle cap and grommet respectively, from Mazdatrix. The s5 pintle cap does fit on to the Bosch injector. I could slide the pintle cap on about halfway with my bare hands, and then I slipped the injector into the hole in the LIM and pushed down. That slid the cap on there all the way.

I haven't checked for boost leaks yet but I'm optimistic. Also if anyone is wondering how to mount that KG parts secondary fuel rail, I used M8 x 1.25 (25 mm long I think) allen bolts. I stacked two M8 washers beneath the rail. So it looks like this:

Allen bolt head ---> mounting hole in the KG rail --> washer --> washer --> LIM

that will allow it to tighten down properly. Make sure you have your injectors seated straight. Use the fuel pump check connector on the passenger side shock tower (yellow two prong connector) to check for leaks. Also, if you need the top o-rings for the injectors (because you are a dumbass like me and managed to cut one up) an injector o-ring for an F-150 will fit just fine. And I found kits with Bosch pintle caps online as well. There's nothing proprietary about the 1680 design... it seems to be a typical Bosch injector.

 

This is some helpful information.

 

alright guys it's official. I pressure tested the car up to 12psi today and no leaks from the injectors. So from this thread we can say that your options if you get the 1600's are to use the hose method mentioned by Ted or to use stock injector grommets and s5 pintle caps.

 

Good that It worked out for you arghx!

 

I finally found the pictorial thread I was talking about earlier. Unfortunately, It's no longer available.

http://home.mn.rr.com/linnihan/1600c..._injectors.htm

 

Glad to hear you got that sorted out.

 

Can the pintle caps be taken off w/out damaging them?

Thanks, Ed

 

If you haven't purchased them yet you can get them here. The beauty of getting him here Is that they address the pintle caps by milling them for you so fittiment Is no longer an Issue.

http://www.fiveomotorsport.com/Injector_MILLED.asp

 

I already have them(blue tops).


Thanks, Ed