Very nervous here. Just replaced a non-working check valve (open both directions) between the charcoal canister purge valve and intake manifold, in hopes that the intermittent gasoline odor might have been caused by that. Didn't work. Now, wifey says that while driving she gets a fuel smell simultaneously with rough running. Car is a nearly-stock 1994 with 90 K miles. I am unable to locate the specific area of the leak by nose. The garage is filled with the odor, but underhood I smell only hot engine. I have previously looked at the fuel path from tank through filter, down to the pipes running from back to front, and up into the driver's side of the engine bay. No apparent leaks. I know the FPR and FPD are buried under tons of "stuff" on the passenger side of the bay. Could be a leaking injector O-ring, bad hose, bad FPD, etc, but no obvious smell on that side of the engine either.

Although I have successfully replaced all the vacuum hoses (with Viton), that project convinced me that I would really rather not tear that engine apart again.

Would you have any recommendations on how to diagnose & fix this issue? I have found Huntington Beach Lincoln-Mercury-Mazda, our closest Mazda dealer, to be fine in the parts dept, but "not wonderful" in the service area. We are reasonably close to Irvine Mazda, but previously I have had their only "rotary tech" refuse to do the vacuum hose replacement job with anything other than OEM hoses, which is why I did the job myself. Are there any independent rotary mechanics in the Orange County area you can recommend? Or should I take on this task not knowing how to determine if it is injector, FPR, FPD, or something else??

 

99% sure it is the FPD

 

http://www.rx7.com/store/rx7/fdfuel.html

 

Davin,

Thanks for your opinion, and for the link.

 

no prob. i have seen horror stories of FPD giving out and thier whole car catches fire. i dont want to see that for you, not in the least bit!

 

I can almost guarantee you it is the fuel pulsation dampener. Highly recommend getting the car in to fix it ASAP. Especially if wife is in the car. Don't want to put anyone else's life in danger.

When those things leak, probability of engine fire is quite high. Search for FPD and you'll read the horror stories.

 

+1

 

Decided to do the troubleshooting myself. Have ordered new FPD and set of injector O-rings from Rotary Dynamics. Maybe I am lucky and have bought the right parts. We will see. Tomorrow is "begin teardown" day.

 

Well, this is ugly. The manual says to remove the extension manifold, and the picture shown of the fuel rail/primary fuel distributor/fuel pulsation damper shows the parts clearly just on the engine side of the lower intake manifold. However, no mention is made of the horrendous amount of other stuff that has to be removed in order to even see the fuel delivery area. In the pics below, the first one is of the actual location of the parts of interest, and the second is of our '94 after the solenoid rack has been removed. I guess the fuel rail is down there somewhere under the wiring harness... but I sure can't see it! Working on this car is like peeling an onion.

 

+1. I started to replace mine one time, removed the coils and got to the point where it was time to take out the solenoid rack. Got stuck and said f**k it and put it back together.

 

Haha, unfortunatly my car did catch fire when I let cracked and leaky injector insulayers go...My fire ate the solenoid rack and I replaced everything myself having never seeing it before and hte car ran fine.

If yyou need any help just email or PM and we will get it handled.

 

Today I was finally able to see the FPD and the fuel injector connectors. Don't plan to pull anything further until the new FPD and injector O-rings arrive on the 16th. Does anyone see in the pics attached a clue as to where a fuel leak might be?

I know a lot of you have done more serious work than this on your FDs, but to me this car is the worst to work on in my memory. The sheer number of electrical connectors and vacuum hoses, the difficulty in removing the solenoid rack, and just the way everything is packed together like atoms in a molecule, is daunting. If I were not retired I would never have the time to do anything under this hood. My Miata is sooo easy to work on...

 

Heh, yeah I'd say that massive wet spot would be where to aim. (lol)

I agree they really oversimplify how tricky it can be to work on the fuel system. From where you are now it's reasonably straightforward, but I completely removed the fuel rail from the engine to push out the injectors and remove the FPD.

Does the car boost well? Now is the perfect time to test the solenoids and toss out the bad ones.

Dave

 

Well, it feels fine, but I admit to not having a boost gauge, so I have no idea whether the pattern is 10-8-10 or something weird. I do have a boost/vac gauge in my Miata, but wifey wants nothing other than stock in her car. I was able to convince her of the wisdom of replacing the pre-cat with a DP, however.

I have a variable-voltage power supply, so I guess I could test the solenoid rack while it's out. I suppose any change in airflow in response to a 12 volt input across the solenoid connector proves it's working, right?

 

Well I use a 9V battery for simplicity. That's enough to demonstrate a 'click' meaning it's not seized. But there are other ways that solenoids will perform less than acceptably:
1) leaking in either the on or off position
2) coil losing continuity when hot
3) internal solenoid spring loses it's compressive force (for whatever reason), such that the pressure on the output nipple causes it to stick in the 'on' position or at least slow it down. This really only affects the turbo control pressure solenoid, since all others output vacuum.

You can bench test for all of these conditions using a multimeter, 9v battery, and mityvac and pressure gauge.

Regardless, I would only embark on this if you have access to the tools already and *like* preventive chores, or you have found the boost isn't working right. If all you want to do is test her car, just plug in the boost gauge and run it through the passenger side window for a test drive.

Dave

 

LOL! It's completely torn down now, so I'll do the tests... I have a MityVac. Not because I "like" any kind of chore... but because I don't want to tear this thing apart again because I missed something. It will be bad enough later after I find out I pinched a hose, or forgot to reconnect a connector, or something.

 

I created a problem in removing the primary fuel distributor and secondary injector rail, and I'm wondering if anyone knows how to recover from it.

There are two rigid plastic tubes routed up from the nether regions of the engine, that each connect to a vacuum tap; one to the front rotor housing and one to the rear. They are pushed over nipples and clamped. In pulling off the primary distributor, it caught on the tubing to the rear housing and broke it off. There is plenty of slack to trim off the tubing and push it back on, but the clamp (and the tool to clamp it) is a mystery to me. How can I repair this boo-boo? (I attached a pic of the area.)

Thanks!

 

Ahaha, the oil metering lines (OMP lines). I almost suggested replacing them earlier, since they get so brittle.

Well I think you can maybe repair them if the crimp came apart, but really you'll be better off replacing them. I fiddled with mine when I broke mine, and the tubing is far too brittle to fit it over the fitting again. But run a search - I recall someone managed to make their own fitting and did a very clean job of it.

New OEM lines are like $65 for a pair, and they will last another 100k. Very commonly replaced during engine rebuilds.

To replace them, you need to also remove the alternator, front engine bracket, vacuum chamber, and whatever else you need to access the other end all the way down underneat the air pump. Personally I would replace them.

Since you have the Mityvac, I do recommend testing the solenoids. If you want I can suggest some much more useful tests than what the FSM will tell you.

Also, you may consider pulling the injectors and having them cleaned/flow tested. Generally they run quite a bit better, and in many cases old injectors drip a little fuel which causes extreme temps from running very rich at startup, or poor fuel economy. FYI, in a few cases the injectors don't function perfectly so if you're under pressure to get it all wrapped up I might say to let them be. For safety sake, changing the o-rings is the more important matter, and IIRC you are doing that.

Dave

 

fyi - gotham racing and another place (maybe rx7.com) sell braided steel oil metering hoses. Somewhere around $100

 

Ah, those are the oil injection lines, eh? Very odd to me that they share the same location with vacuum/pressure taps that run hoses to the solenoid rack.

Well, before your responses, I came up with a 2" long, 1/8" ID Viton hose coupling. You can see in the pics that I clamped both ends; I could not have done this if the plastic tube had not been rigid! Although the near end of the coupling looks high, the Viton is flexible and will push down to the rotor housing. Hopefully it will fit under the wire harness and not leak oil. (I just really do not want to tear even more of the underhood stuff out to replace those lines.) They seem to have worked OK even being brittle; I just need to be careful when reinstalling everything.

I have electrically checked all the solenoids except the charcoal canister purge valve solenoid, which is still underhood. All switch at about 6.5 volts or so. I guess I will repeat those tests adding the MityVac, and verify the valves are OK and don't leak.

I have replaced the O-rings of all four injectors, and electrically tested them. They all open at around 3.4 volts. I also put a little finger over each pintle and verified that it retracted when the injector switched "on." I have replaced the FPD, but am not convinced there was any leak there. I have a new O-ring for the FPR, but have not removed the FPR from the rail yet. I suppose I should check the operation of the FPD and FPR with my MityVac just for drill.

The injectors seem clean and the primary fuel distributor looks good; I am replacing the two fuel hoses to the FPD and FPR even though they also look fine.

I live in fear that I will finally get all this back together and wifey will drive home and say "I still smell gas."

 

might as well get the injectors clean. with that much mileage you might need it.

also be careful reinstalling the injectors. some people have problems with re-installing due to the seals being brittle.

 

I should have the plastics oil lines. You can have them for free and I live close by to you. I could have given you my used fpr to but didn't get the old one back. I have new o-rings to.

I regetrably paid for the vacuum hose job when I was a newb. That was a mistake, glad you did it yourself. Not difficult, just very time consuming. A waste of money if you don't do it yourself!

I would get the boost gauge with a single pod (have one of those to). You can see mine. It still looks pretty stock to me. Personaly, I think you should have boost and water temp but two may be much for her.

Oh 93's had some kind of fuel recall and the kit replaced some lines but I can't remember if it included a fpd though. Mazdaformance used to sell the complete kit.

 

Oh, I forgot. On the 1st page pic on the left you can see the ACV check valve. You should replace it if you can while it's easy to get to (for smog reasons). Sent you a PM.

 

All 4 injectors are reinstalled. They went into the fuel distributor and rail easily since I put dielectric silicone grease on the O-rings. New FPD is in also. I appreciate the offer of the plastic tubing, but I don't want to tear the thing down any farther than I already have. Hopefully my repair will hold; it seems very secure. I cleaned up the ACV check valve and the valve body when I did the vac hose job, and the car has been smogged twice since then with good results.

I have a new problem; per Dave's recommendation I tested 8 solenoid valves using the MityVac. I found that two are apparently "stuck open," even though the solenoid clicks at the same voltage level as the working 6. One is the "Turbo Control" solenoid valve, and the other is the "Charge Relief" valve, the one above the row of 7. It was sort of hairy doing this test since there are multiple air paths... I managed to isolate each of the valves to a single path for its test. What now? Can WD-40 or alcohol be squirted into the valve openings to clear the stickiness, or do I need to buy new valves?

 

I've tried the WD-40, and it helps with stuck solenoids, but I don't know the effects in the long run. I can't think of why it would be bad though.

New solenoids ($55/ea) is the sturdy answer, and if you opt for that I suggest changing the turbo control, charge control, charge relief, and turbo control vacuum (the metal one on the ACV). Those four control the boost, are under the greatest loads, and need to respond instantly.

If you want to be cheap, it will take an hour or two to test them thoroughly. Tedious as it is, I find it easier than pulling the UIM to change them later.

1) Perform your tests with 10-12v. 6v is not realistic.

2) The 'on' input nipple is the plastic one pointing opposite the electrical connector. Apply 25inHg and look for leakage. Apply voltage to the connector, and it should immediately vent out the upward facing output nipple. Do the same with 15psi. The 'off' input nipple is the metal one, under the connector. It should flow freely to output with no voltage.

If there are any that are simply stuck, try shooting some WD-40 in there, let it soak, then clearing out the oil. Rap the metal nipple on a hard surface and try it again.

3) The turbo control solenoid that sits in the rack is special and deserves its own test. Put a hose leading to a pressure chamber or an actuator. While applying voltage to set the solenoid on, apply 15psi to the on input nipple. This will load the chamber on the output side with 15psi. Now turn off the solenoid - it should vent immediately and fully out the 'off' input. If sticks, or leaks for a bit before venting, it didn't pass. I repeat this test until I find the highest pressure each solenoid can crisply vent. Out of all the similar solenoids, put the one that cracks consistently at the highest pressure in the location for the turbo control. Put the second best in the charge control, and 3rd best in charge relief.

4) Put them all in a 250F oven, loosely covered in foil, on one of those hollow cookie sheets or a wooden cutting board. After 20min, check the resistance. It will be higher than normal (50-75Ohms vs. 35). You're looking for ones that go open circuit when hot, discard them.

That's a lot of testing, but IMO it's what is necessary to guarantee nice response in the car.

Dave