flooding out FC3S4 N/A
 

Im working with the guy selling me an 86 FC3S4 to get it running before i have him paid off. initially this is what he said:

I secured a used CAS and he swapped them but

He's got a T-II FC for his own and is a competent mechanic. I just picked up some known good injectors to send to him, but does anyone have any additional thoughts on what might be causing it to flood that fast?

Low compression is a likely culprit. If gas blows past the seals much it'll wash out the oil needed to seal the chambers, and then it'll just crank and crank because it can't build compression. This is a very common problem with low compression rotaries. A temporary fix sometimes works, you can install a fuel cut switch so it doesn't just POUR fuel into the chambers on startup. You probably will have to rebuild a motor with that low of compression before soon though. I would keep that in mind. My TII came to me with probably 80psi compression and had the same trouble starting and I used a fuel cut switch to help it start. I was probably lucky to get ~8,000 miles out of it before it let go. I knew it was coming though and I had stocked up on all the parts I needed for a rebuild, so when it died I was prepared to build myself a new, better motor.

i thought 80-90 psi compression was good....(HIS T-II has the 50-60psi, not the N/A he's selling me)

does the FC have a flood threshold for the throttle? floor it on crank and it cuts fuel?

any way to temporarily re-oil the seals? put a bit of oil in through the intake or spark plug holes and crank it over?

injector problems CAN be the cause of the issue. I had a string of rx-7s come through once that all had serious running issues from constant flooding, stalling and bucking. They all turned out to have bad injectors.

you know, that might have just been the gauge.

I tested my car with two gauges that both got 90psi, and then with this other one that only displayed 50psi, and I was like WTF?

So it might just be the gauge.

90 is rebuild time. My NA rotors pump out 110-115 on both faces with pulses up to 60PSI on any single compression.

well, i can't afford a rebuild ATM, (student, i.e. broke as hell) provided the engine is in good shape, can a rebuild be just the apex, side seals and a small list of other parts? the master rebuild kit on Atkins was like $900...

Im hoping that its the injectors and she'll run with better ones. im guessing an oil change is in order after all the flooding.

I know I will need to rebuild the engine, but a 100k one is better than a 140k one, so for now it will do. (old one had a coolant seal pop in 3 places on the front iron)

50-60 psi is really low, even for a TII. And you can't compare compression numbers between an NA and a TII. TII's come with lower compression rotors and NA's are higher compression. So if you had an NA and a TII that both got 80psi, the NA is probably a lot weaker than the TII.

So back on topic, the motor probably has lower compression than he's telling you. If the injectors you sent him weren't professionally serviced then they will still probably leak and cause more flooding. The injectors and low compression are what cause flooding.

any particular reason you think the compression numbers are lower than he says? (hes a long-time member of a forum im on and a standup guy by general consensus) FWIW the injectors i sent came out of a running N/A so...*shrug*

on the subject of rebuilds, is there a quick and dirty rebuild to get the compression up to where it should be? im not liking the $900 pricetag for a master kit... aside from seals etc, can you do just the seals and such and have a refreshed motor?

The only way to save money on a rebuild would be to see which seals are still in spec (IE Apex seals). If your Apex seals are still in spec you can probably find a kit that doesn't have them included which can save you some money. Also, find out if your oil rings are in good condition as well as your side seals, then you might not have to get those seals either (though it is a good idea). After that you will just need a gasket and seal kit for taking it apart. Honestly if you're getting low compression and you're flooding out it very well could be leaky injectors in which case your compression numbers are lower than what they should be. If the injectors are not faulty and are in good condition you're still low on the compression side which can mean a few things. Your apex seals are out of spec, your side seals are toast, etc. It just all depends.

ok, ill see what happens with the new injectors. ive had experience with gunked injectors on my Duster, so i know how much of a PITA a stuck open injector is.

Atkins had a rotor kit or something like that which was apex, side seals and some other parts. is there another supplier for rebuild parts other than atkins?

There are, but their prices are more expensive from the ones i've been able to see. Not sure though. Check their vendor section for a deal they're doing with re-build kits. It's not a bad deal all things considering.

Well like its been said already, the causes for a flooded motor are leaky injectors and or low compression. Just because you got injectors from a running car doesn't mean that they wont leak either.

The S5 cuts fuel if you put the pedal all the way down, but the S4 does not.

http://www.rotaryresurrection.com/2n...nflooding.html

well, i sent out the final payment on the FC. Ill be picking it up in 2.5 weeks! :)

Still havent figured out the flooding though. Secondary injectors got switched but it still doesn't quite catch. Once i get it in my posession, ill swap the primaries and see if thats the issue.

Would a bad FPR cause a flood on start?

technically yes. Only reason i can confirm this is mine on a car i used to have some how went bad and it would not relieve fuel pressure to the return so the pressure was quite high.

I thought so. ill keep that in mind if swapping the primaries doesn't fix it.

(ironically i think i have a FPR issue on my DD too lol)

no not really. if you tear down the motor to rebuild just a few seals you will be wasting a ton of time for nothing, if you tare that thing apart make sure you do it proper and have a master kit waiting for it. you'll be doing yourself a huge disservice otherwise

Why on earth would you need a master kit? Especially before what you know is in spec and what isn't?

Why replace the rotor bearings if they're still in spec?
Why replace the stationary gear bearings if they're still in spec?
Why replace the Apex seals if they're still in spec (assuming the engine has 2 piece seals)?
Why replace the side seals if they're still in spec?
Why replace the corner seals if they're still in spec?
Why replace the oil control rings if they're still in spec (I'm referring to the hard rings and not the soft seals which are replaced during a rebuild)?
etc
etc
etc

You shouldn't ever buy a rebuild kit before you know what's in spec and what isn't. You can save so much more money than just buying a master rebuild kit. Sure you can buy a master rebuild kit and be done with it and know that you're going to have an engine that should theoretically last over 100k, or you can replace what's been worn out of spec and get an engine that should theoretically last over 100k.

/\ Good point, and besides, it's not like most people are going to end up driving their cars for another 100K in the first place... at least, people with nicer cars that dont drive them every day.

i'm just curious why your making payments on a non running car? hopefully you didn't just pay 12k for it

college intern + making crap + bills = payments on a $300 car :)

Vex, you make good points on the rebuild thing. same thing goes for piston engines. why buy a whole kit w/ pistons, rings etc etc when all you might need is a couple gaskets and bearings? :)

Or you could make the point-
Do it once do it right-
Why use old stuff even if its perfect id rather rebuild once and replace everything than fix what is bad at this time-

If the parts are in spec, they're going to be equivalent to if not the exact same as what you replace them with. There's reasons why the FSM states "if out of spec, replace". There's no point except bragging rights and maybe a false sense of security with just swapping in with a master kit all the parts that are still in spec. You run the same exact chances of failure with new parts that are spec'd that you do with old parts that are spec'd. Now, if we were talking about re-using soft seals, then yes. Replacing soft seals are mandatory for correct function.

thats the point i was trying to make ill take the false sense of security anyday

Let me put it this way: You have a used journal bearing that shows no sign of wear. You spec it and it shows the perfect conditions for the bearing to have.

Compare it to a new journal bearing you have that shows no sign of wear. You spec it and it shows the perfect conditions for the bearing to have.

What's the difference?

id still toss the old one. i guess you dont get my point eather, i get what your saying, and on say, a pulley bearing i totaly get and understand your point. its something that is easily accesable, and if they pulley is still up to spec and has no signs of wear then why replace it. if im tearing down an engine for a rebuild id much rather use a master rebuild kit and not have to worry about specing every single piece. just replace it and get it over with.

:beatdeadhorse5:
Even with new parts you should still be specing them prior to install. At no point in the rebuild process should you not be specing any part in a high tolerance location (all bearings and seals). So again, beyond a false sense of security, extra work, extra money, there is no benefit (can those really be called a benefit?) to replacing an in-spec part for a new in-spec part. If an old in-spec part does eventually fail in the engine, it's not going to be because the part was old/tired and broke from fatigue, it will occur--more likely from an out of spec, improperly installed, or catastrophic failure from a pre-ignition event. All of which would cause the same exact failure of a new part in the same way.

Now that being said, some parts are better off being replaced even if they're still in spec: Apex seals, if they're of the old 3 piece kind, can easily be upgraded to the newer 2 piece without much issue or head ache. In spec 2 piece so long as you remember which rotor they came from and which apex they came from on that rotor can easily be used for the rebuild if there's enough life in them. If however the apex seals are getting closer to the wear limit (6.5mm~7mm) One should think about replacing them with new because failure of those seals will occur sooner than a new (8mm) apex seal (for further clarification look at the ash content of oils thread in the general tech section). Apex seals are wear parts.

When it comes to bearings however there is absolutely no benefit to replacing the old with the new, unless of course you're stepping up to a 3 window, or race bearing. This is because there is supposed to be no actual contact between the eccentric shaft and the bearing, as well as the rotor bearing should make no actual contact with the eccentric shaft. The journal bearings use the principle of shear to keep wear from occurring, and as such the oil will play a much bigger role in the life of those parts than the actual time in the engine of the part.

So, if I still don't get it. Please explain it to me where the benefit comes from replacing old-in-spec parts with new-in-spec parts?

Well, i towed my "new" rx-7 home this weekend. 1400mi round trip in 36 hours. Wend down with a 2.3L 4-cyl 2wd manual ranger and a tow dolly to south carolina to pick it up. Loaded the car onto the dolly backwards (drive wheels off the ground) and trundled slowly back. Couldn't go above 55-60 as i had trailer-whip when i hit 65+.

The car is the one that was for sale HERE and there are a couple pics as well.

As far as i can tell, it is in good shape. a SC car all its life i believe, virtually no rust that i saw. Its actually a 87 according to the title with 170K or so miles.

There are some small issues with it (aside from not starting/running)
1) shifter has vertical play, i think the retaining plate is wore out or broken
2) right side mirror housing is broken
3) a triangle-ish vent cover on the right of the dash is MIA (grey interior)
4) e-brake handle casing is cracked and separating
5) minor dings, scratches, loose or cracked interior pieces
6) one of the rear glass latches isn't latching
7) driver's door doesn't lock
8) clutch pedal likes to stick down at the floor (stuck PP maybe?)

As for the motor, Im planning on getting a battery and seeing what it does when i try and start it. I'll probably pump out the tank and replace the fuel filter as well as an oil change and possibly a coolant change.

I still have to change the primary injectors and see if that helps with the flooding/starting issue. I'll post up more later this week when i get a battery and a chance to fiddle with it.

It needs a little TLC but it will definitely get that now :) BTW, is there supposed to be an RX-7 badge on teh rear? all i have is a "Mazda" one.

And if anyone has an s4 or s5 parting out i'll be interested in parts/pieces to get this back into decent shape :D

lol, I "think" there is suppose to be an RX-7 badge on the rear. Mine's was missing when I bought it.

Well, tried to start the 7 again and had NO spark. Leading coil checked out but the trailing coils had good primary resistance and i could not get ANY reading from the secondary to ground. It seems like the trailing coils are shot and im not sure why im not getting any spark at all. It may just be a weak charge on the battery but any advice would be appreciated :)

You should charge the battery before you try to start the car.

I am sure that you tried adding two-stroke oil to each rotor, but I thought I would ask.

Even with a terrible tune (3-bar MAP tune, 1 bar MAP) my '86 started just fine for the initial start on the Haltech.

If it ever wouldn't start, oil was the answer (although it did pulse to 100+ psi on all faces - without any oil).

(The tune is better now and oil is no longer necessary).

You could also try starting the car with the accelerator pedal floored (after clearing the flood and adding oil). If you can get it running, keep it running for a while, maybe it just needs to be run.

If it is the FPR, you should be able to install a gauge in the line from the primary injectors to the secondary injectors and verify that.

edit: You really should try pull-starting it too.

Its a brand new battery but i will throw the charger on it before trying again

Haven't tried the 2-stroke oil thing, where would you put that anyways? intake or in through the spark plug holes?

the S4 didn't have a flood clear so whats the reasoning behind the full throttle starting?

Also, does anyone know what the secondary coil resistance SHOULD be? and can i run 2 blaster 2 coils in lace of the stock ones? (i REALLY don't want to pay the stupid high prices for stock coils vs the less expensive aftermarket coils) As far as i can tell the Blaster 2's would be fine, the primary resistance is within the OEM spec (blaster 2 - .700 ohms, spec is .2-1.0 ohms)

You can get the coils for CHEAP on eBay or on here.

I am sure that someone has a spare set that they are willing to part with.

The 2-stroke oil goes in the spark plug holes after you have pulled the EGI fuse and removed the spark plugs and cranked the engine for 30-60 seconds with the gas on the floor. (I used a small hose to add the oil.) The plugs can then be replaced. This should get your engine running.

Flooring the gas will minimize the problems due to vacuum leaks and injector leaks and may give the engine a change to get to a good 3000ish rpm before all the starting aid oil is gone.

edit: Be careful to look at required dwell time on aftermarket coils. Rotaries have a tendancy to saturate inexpensive aftermarket coils at higher revs.

ahh ok, i did find a set of trailings on ebay for $49 shipped...(kinda wanted them NOW though lol) going to see if the junkyard here has the FC body for the motor they listed and maybe i can snag some trailing coils there...

thanks for the clarification on the oil and flooring it. it makes sense now :)

well, i fiddled with the 7 today a fair bit. picked up a trailing coil set and some misc parts for $50 at a J-yard (had 2 89+ GXLs). pulled the plugs, pulled the car in gear to de-flood the motor and actually got it to start while flooring it, it was running like crap though, still seemed to be drowning out. once i let it stall out after 30-50 seconds, i couldn't get it to start at all and the plugs were constantly wet with fuel.

picked up 6 qts castrol GTX 20w50 and an oil filter and ordered plug wires, plugs and a fuel filter as well. going to do a coolant drain flush and fill as well.

Decided to drain the tank and got about 7 gallons of varnished fuel out of the car. I think the varnished fuel has gunked up the primary injectors causing it to flood but i don't know if the intermediate intake gasket is reusable. the parts place list the "intake manifold" gasket at $50+ and 2 "plenum" gaskets around $9-$11. Also i forgot to ask about a pulsation damper.

I tried replacing the worn out shifter with one i got from the 89+ but i still have vertical play in the shifter and the motion isn't great, and its picky about going into reverse. Im thinking about getting an ebay short shifter with all new hardware to see if that fixes the issue (can't afford a mazdatrix one)

I also re-did the battery connections and bled the clutch system as it was dry. i still feel like there should be more travel for the clutch but i think that is going to be found in adjusting the clutch pedal.

If there is any other advice, im open to anything about now. One good thing is i dont have any dead faces as i got "pissh"s from all rotor faces when i was de-flooding the motor.

Check voltage to leading coil, should be same as battery voltage.

If that checks out and you're still not getting spark on leading i'd try changing out the leading coil, the trailing won't affect the ability to start too much.

I'd definately clean the injectors though. If you have varnish in the tank though i'd drop the tank, clean it out really well with brake cleaner, change out the fuel sock on the pump before chaning it out and flush the lines out with some alcohol before putting everything back together. My T2 has the same issue.

You may have a serious vacuum leak.

My '86 was exactly like that when I got it, the vacuum line to the brake booster was MIA.

If the car runs when flat on the floor and not under any other circumstances, it is likely to be either the TPS, MAP, or a vacuum leak.

I guess I could see the vacuum line to the FPR missing or improperly connected.

Does the car still have all the emissions intact?

I think that a fuel pressure gauge would do you a lot of good (determine if your FPR is bad or malconnected or you have a plugged return line.

I have known people to try the ingenious plan of crimping off the return line to get more power (some old truckers used to do that with reasonable success on ancient diesel engines). It doesn't work with a gasonline engine. Infact to get more power out of a stock rotary, you need LESS fuel.

well, for one i saw that the hose connecting the primary fuel rail to the secondary has a nasty kink in it. That might be causing the issue.

As for the varnished fuel, is it that hard to drop the tank? it looked like 2 straps and it'd come right down.

AFAIK it has all the emissions stuff still attached, its a relatively untouched rx-7 :)

Wile i can't spot any missing vacuum lines it doesn't mean that some of them might be bad.

the leading coils checked out and it DID run, the issue i believe is in the fueling side.

I have a set of known good injectors, the secondaries were swapped by the seller but not the primaries. I want to swap them after seeing the fuel i pulled out, but i don't know what gasket to get to replace the one between both upper and lower intakes