wstrohm

I've decided to replace the O-rings in all 4 injectors, after looking at the old ones in the primary injectors. I bought a new digital caliper to replace my old dial caliper, which gave up the ghost on this job. Re-measuring the old upper O-rings gave O.D.s of 21.3 mm and 21.4 mm on the injectors, whereas the new O-rings just received measure ~22.4 mm out of the package. The fuel distributor bore diameter is 22.05 mm, so I can see why the old one was leaking, and am surprised that both were not leaking.

I removed the gas cap and the dripping stopped. But I still don't know where it was coming from. The only thing open to the air in the engine compartment is the primary fuel distributor, and it's not wet... the bores are dry all the way down. Maybe it just took a long time for the fuel to run down the outside of the engine and make it to the floor from when I ran the first pressure test. So that is still a mystery to me. The car is jacked up higher in the front, but I suppose there could still be fuel level in the tank higher than something under the hood... but higher than what????

wstrohm

Problems getting the NF01-13-ZG3 8 mm O-rings from Mazda. Two different sources (Ray Crowe and also Huntington Beach Mazda) are supplying the NF01-13-GZ4 part in the -ZG3 packages. HB parts guy is re-ordering, but it looks like Mazda warehouse is packaging the wrong parts in response to the correct orders.

wstrohm

As a backup for these O-rings, I just ordered (online) 4 ea 2 mm cross-section, 18 mm I.D.; and 4 ea 3 mm cross-section, 8 mm I.D. Viton O-rings. IMHO Viton is a superior material for this application anyway, and if they arrive first I will use them instead of the very expensive Mazda parts, which are probably EPDM synthetic rubber. If Mazda comes through first I will use the stock parts.

j9fd3s

iTrader: (3)

is the blue sticker incorrect or the yellow sticker? if its the blue sticker, the trouble is in Japan, the yellow is from the US warehouse. 99.9% of the time its the US warehouse

wstrohm

The mis-packaged parts had a yellow sticker. But Ray Crowe sent me an e-mail stating that the problem was in Japan. (The correct ZG4 parts had a pink sticker.)

I told Ray not to ship the correct parts... yet. I'm kinda hoping the Viton O-rings will arrive before our local Mazda parts guy calls me and says he has the right ones. Viton is much better anyway, particularly its lack of compression set, which has caused this leakage problem (I think). If the Viton parts get here in the next couple of days, I can compare them to the stock O-rings and see if they can be substituted. If so, I will get a refund ($60) on my local order with Mazda.

wstrohm

H.B. Mazda came through with the NF01-13-ZG3 (8 mm) parts today, but of course they were marked as NF01-13-ZG4 (the 18 mm upper O-rings). So now i have enough new stock O-rings to start putting the car back together, but I will wait for the Viton parts to come in so I can see the differences, if any, between them and the stock parts.

I was somewhat amazed at the difference between the old 8 mm and new 8 mm stock O-rings. O.D. on the old rings is 13.35 mm, and on the new ones O.D. is 14.43 mm. Compression set has to be the cause. (Viton shouldn't do that.) I'm guessing these stock rings are made of EPDM synthetic rubber. However, they lasted for 21 years, so no complaints here except for the almost inaccessible location.

wstrohm

Ref. my previous posts, the stock O-rings cannot be EPDM since it is not recommended for petroleum resistance. They must be Buna-N or equivalent. Viton O-rings are due to be delivered today. This should be interesting. If the dimensions are OK, I'm leaning toward Viton.

wstrohm

Ordered the Viton O-rings on 2/11, shipped 2/12 via USPS Priority 2-day, est. delivery 2/14; now 2/16 and still waiting...

j9fd3s

iTrader: (3)

newman!

Sgtblue

iTrader: (16)

lol, nah....Cliff's on it! Hopefully they'll be worth the wait.

wstrohm

Viton O-rings arrived today. Could not use due to O.D.s being too small (upper 22.0 mm, lower 13.9 mm. The new stock O-rings are 22.4 mm and 14.43 mm free diameter and 22.75 mm and 14.64 mm mounted on the injectors. Installed the injectors and pressure tested for leaks. No leaks anywhere I could see. Installed ACV valve and hooked up all electrical connectors and vacuum hoses on the solenoid rack. Tomorrow will attempt physical connection of the rack (4 impossible screw attachments).

j9fd3s

iTrader: (3)

i have an FD engine in my FC, and the vacuum rack really puzzles me. on the one hand its actually really cool, because its modular, so you can remove the emissions, or sequential turbo stuff if you wanted, and whatever you had left would still be really tidy. or you can just have the coolant pipe, manifold support and fuel lines.

on the other hand its built up from like 42 different parts, and how did they expect to make money with something like that?

wstrohm

Job done. A new LED "headlamp" (for my head, not the car) made reassembly much easier. No fuel leak, engine runs perfectly after initial panic due to (apparent) flooding and difficulty starting. Took for a spin on the freeway, and everything is "kopacetic."

Wife is happy again.

wstrohm

For whoever is interested, a few data points from an almost stock 94 FD with 111 K miles, original engine:

The old fuel injector O-rings were hard and small, not sealing against the mating bores in either the fuel distributor (primary injectors) or the upper (secondary) rail. The mating bores were the same at 22.05 mm diameter. The old primary upper O-ring outside diameters were 21.3 to 21.4 mm; the lower were 13.1 to 13.5 mm (I have no info on the mating diameter of the lower bores).

The O.D.s of the new stock upper O-rings (unmounted) were 22.4 mm, mounted on the injectors are 22.75 mm. This gives an initial interference fit of 0.7 mm (diameter) in the upper bore.

The O.D.s of the new stock lower O-rings (unmounted) were 14.4 mm. Mounted on the injectors they are 14.6 mm. This is 1.1 to 1.5 mm larger than the old rings unmounted.

Pressing the 4 injectors into their bores gave a satisfying "plop" - "plop," feeling the compression of first the upper O-rings and then the lower O-rings as they were pushed totally down. I had coated all of the O-rings with dielectric silicone grease, which helped prevent any damage to them at entry.

If anyone out there has an original engine with comparable mileage, I would guess the O-rings are leaking. If not the upper ones (yet), the lower ones could easily be allowing extra fuel into the rotor chambers, increasing fuel consumption and possibly flooding the engine.

Just a recommendation... if/when the engine is out or stripped to that depth, the O-rings should be looked at and measured. The Parker O-ring handbook recommends that there should be at least a 0.2 mm interference fit on O-rings of all cross-sections.

j9fd3s

iTrader: (3)

...and there was great rejoicing

dgeesaman

iTrader: (7)

Well done man.

Sgtblue

iTrader: (16)

And God saw that the Chaste White FD was good and separated it from the darkness...of the garage.

Congrats. If you're like me, these projects start out as a huge pita and end up making you feel pretty damn good.

gracer7-rx7

iTrader: (16)

Nice work.

Mugen1800

Looks like I joined the club at long last. I haven't checked the FPD yet, but I do think my primaries are leaky. They're a bit covered in some substances...My dilemma is whether I should try to go an aftermarket route with more reliable hardware (rails, lines, fittings, etc...). Apart from the aesthetics of it all, I really don't want to have to go under the manifold ever again (or at least 50+ years...). ​​​​​​​​​​​​​​

DaleClark

iTrader: (55)

To be honest most aftermarket stuff won't be as reliable. They will be leaky and crappy after a long time too. Just get OEM parts and be done with it.

Dale

Mugen1800

FPD just arrived today... or yesterday considering the time of day. Finally got the rats nest removed, and my culprit is the primaries. I'll have to order that o ring it from rx7.com also where I bought FPD. I ordered as a preemptive... not going back under this thing for a while hopefully. I want to change the FPR too, just have to source a new one. Idk what it is but there is this muffled bucking (or whatever that sound is) every so often at idle. I was wondering if it was the FPR or something in that area gone bad? It sounds like it's in the down pipe though.

DaleClark

iTrader: (55)

If you get a spit or miss at idle that's pretty normal. The FD's injectors are some old tech and I don't think I've ever seen an FD with a totally smooth idle. As long as the idle speed is correct. and it's relatively smooth you are good.

Dale

Mugen1800

It use to run very smooth, like you couldn't feel vibrations or anything, but it could be false memory, idk. You did help me calm that thing back down from when I tore the throttle body and everything completely apart. Lol I still tell stories about it. I talked to Fujita last night to find out what was changed and it was just the pump that was upgraded, so injectors should be stock if I have to replace them. Idk if anyone can see the pics. They're pretty gunky. Fuel railsPrimarySecondaryOther secondary​​​​​​​

Mugen1800

Finally got the injectors out of the rails omg. I am hoping I can reuse them because they're too much. I bought o-rings and the sort. FPD is here, but still need the FPR. I'm replacing all screws with SS hex screws, and will powder the rails and rats nest. Before reassembly. I take it these hats on the bottom of primaries aren't supposed to have a split in them. It didn't come off attached to injector either. The o-rings look decent though. Won't reuse them either way. ​​​​​​​​​​​​​​

silverTRD

iTrader: (37)

You should have your injectors serviced while they are out. They will clean them, verify flow CC, spray pattern, replace the o-rings, the works.