Sir Surr

Hey guys, so my tach went out, I have a 12a engine and I probably revved it to 4 cold, and I usually don't push it past 3 until it's completely warmed. ANYWAYS driving home the other day I was going over a hill, (this is the first drive after maybe revving it to 4) and my.engine completely gave out, my RPMs dropped, but everything else stayed the same. I couldn't start it, but I got it started once and it idled at 100 and shook really bad. Ended up towing it to my dad's, he got it to rev to 2 like it normally does and he said it seemed fine, he thinks it's a gas problem. I dont know what this could be, I instantly assumed the worse, blown Apex, but now I'm not too sure. Any ideas? Any help would be appreciated

sequentialsteve

Start with the basics before u assume the worst. Check fuel system then check the ignition. If that all looks good compression test it.

diabolical1

iTrader: (3)

Welcome to the board.

So I'm a little confused. You said the tach stopped working, then you were saying "revved it to 4 cold" and "idled at 100". Are those guesses, or is your tach working again?

If the tach is not working, then that's a fairly good sign that your trailing ignition is dead. The car should run on just the leading system, but not optimally. If the car ran fine before your tach died, then I would focus on getting the ignition systems back up to par before looking elsewhere. Check everything - igniters, coils, plugs, wires and plugs.

If the tach started working again, then I would look at your fuel filter and then your pump.

When was your last tuneup?

Sir Surr

The tach worked again, I think it was a wiring problem. I hit the dash while driving and it worked like normal, that's how I know it idled around 100. I'm gonna check this weekend for fuel lines, plugs, coils and such. I had a coil problem before and had to get a new one, so I'm gonna get those tested. Does anyone think it could be a severe vacuum leak? I was going to check that too, gonna research on the forum how. If anyone wants to know I'll keep them updated

Update: I might have a faulty gauge cluster. My original one that came with the car was literally broken, (pieces missing from the motherboard?? They snapped off) so I bought a new one, and this one is giving me trouble too. Any ideas what to do about it?

diabolical1

iTrader: (3)

Vacuum leak is not off the table, there are a few places on the manifold where rubber hoses can crack or break resulting in a leak. However, I would tend to think given you said the car shut off while driving that there was probably disruption in fuel supply.

Sir Surr

Alright I'll check it if I have time. Got a lot of stuff this weekend, but I'm determined. I'll update yall on what I find

Sir Surr

Alright so I checked the car today, everything for the ignition seems fine, except my spark plugs are extremely fouled, looks like someone took black spray paint to em hah. Gonna change those out, sounds like the engine is flooded too. Next im going to check the gas, which seemed fine but I'm gonna be more thorough. There was one thing, in my carb with the top lid off (lid of the air filter part) when I tried to crank it a puff of something came out for a second after I stopped cranking, again any help would be appreciated, thanks guys.

diabolical1

iTrader: (3)

What fuel pump are you running?

Sir Surr

I dont remember, I got it from a friend who thought it was broken. He was going to junk it. The fuel pump was changed about a 2 years ago, one of sitting and one of driving less than 5k miles. I got it started an hour ago and warmed her up, it still idled like crap, I think it might be an apex because the whole thing sounds weird, revving sounds like normal but then it also sounds like just something (maybe a rotor) is just spinning and it just sounds like its trying to move air. The exhaust doesn't sound like it used to or anything. Im gonna compression test it another time and hope for the best. I have spark on both trailing and leading, and everything else looks fine. How would I go about checking the pump if you could help?


EDIT: I'm not sure how much this matters, I know people say rotaries blow after 80k miles, I find that to be false, I think it depends how well you maintain them, but my engine also has 260k something miles on it, it was the original 12a with the car

diabolical1

iTrader: (3)

This is the reason I started asking about the pump. It reminds me of when I was tuning my Dell'Orto and the regulator I had was still allowing too much pressure. The car would flood so bad that it would try to stall out, it very well may have done so a few times, but if it did, I don't remember. So I just want to know what pump you have in order to know if it's something that we should be looking into.

If you lost an apex, so bad that it's affecting starting and idle, then you should be able to tell by simply turning the engine by hand with one plug removed from each chamber. You will easily hear (or not hear, rather) the two dead chambers. That said, a compression test is a great idea. It is useful, actual data. Especially at 260k miles! Congrats, by the way.

I'm calling attention to this simply because I see/hear it all the time. I'm glad you are able to see it for yourself and now can all bullshit when you hear it again. With maintenance and some common sense, these things can run to the other side of 300k and still be strong. I'm not going act like that's the overwhelming majority of the cases, but it happens in more than just a handful.

BuiltRB25

I would definitely check the fuel pump and any fuses/relays that pertain to the fuel system. It almost sounds to me like your fuel pump locked up.

Sir Surr

Alright I know this has been a long time, but I checked the car by removing the spark plugs and trying to listen for the 3 distinct poofs, and I'm almost positive I blew an apex seal. I'm planning on taking the engine out as soon as I have enough for a rebuild kit from Atkins, if anyone has a cheaper way to get one please tell me. I'm gonna search the forums and watch rebuild tutorials and I also bought the Haynes manual for a 79-85 the other day. Thank everyone who replied and if anyone could help me with anything else I'd greatly appreciate it. There's a few major things I'm planning on doing to the car before it runs again, I'd say if I were lucky it should be running around the summer of '19 but that's hoping.

KansasCityREPU

iTrader: (9)

Before pulling the engine, do a compression test.

Sir Surr

Okay, did a compression test today the front rotor was at 60, 65, 65 (hopefully I'm saying this correctly) the rear rotor barely didn't anything although one face had another 60. I read that if one Apex seal goes it ruins 2 chambers, is that correct? it makes sense

Sir Surr

Update: I did more compression tests on the rear rotor for a more accurate reading, and I got basically nothing again, then that one rotor is at like 20-25 now. And that was for the second and third test. I'm pretty sure this is extremely bad, right? Can I expect a rebuild or do you guys thing my rotor housing is scratched to hell?

KansasCityREPU

iTrader: (9)

The engine is gone. If you want to get it started you might try a pull-start and popping the clutch in second gear. You have to be really careful doing it this way so you don't hit your pull car. A big hill also works. This will raise the RPM from 200-250 using the starter to 2000-2500. This won't fix anything but it will give you an idea of how it runs.

Sir Surr

Ive started it without pull starting, I still can. It runs like crap and tries to idle around 100, but when I have gas on it it seems to run, I've moved it this way because I had no way else, but it runs it's just a ***** to start. Thoughts? Do you think I should try a rebuild? I was planning on one, or trying something

KansasCityREPU

iTrader: (9)

I'm surprised it idles at 100 RPMs. I've never seen a rotary idle that low. What happens if you hold the choke out to try and raise the RPMs? Most of the time when they run one only one rotor, they won't idle below 1500-2000 RPM.

Sir Surr

I let some mechanic shop that I heard was "good" try to find an electrical problem for me because my dash gauges didn't work, because of a problem, had to get a new cluster. But when I got it back I was pissed to hear that they didn't even know it had a choke and it was broken since then, I warmed it up manually with my gas pedal keeping it at 1500 then driving it after. For a better explanation the engine idles at around 100, then sounds like it's about to die out completely then brings otself back momentarily to about 250, which then it drops back to 100 and repeats. If I have my foot on the pedal and make it at 750 or around the idle it sounds bad, but it doesn't try to die

KansasCityREPU

iTrader: (9)

Time to rebuild. The first step would be to remove the engine and disassemble to check what parts are reusable. Fingers crossed the rotor housings are good.

Sir Surr

Alright thanks everyone! I'll keep updated, Ill ask anyone if I need any help, I'm gonna check the forums on engine removal too

Sir Surr

UPDATE
Its been four months, been kinda busy but I managed to pull the engine and disassemble, and bad news. The rear rotor (the bad one) was completely gone, along with the housing, gouges and scratches everywhere and one really deep scratch. Also the other rotor was fine, but the housing near the bottom had a part about an inch long and 1mm wide where the chrome was worn, so from what I've researched that's not really reusable either. Sad news. I was thinking of buying an engine from Ernst at rx7world, anyone have any good news about them? I've searched the forums and seen both good and bad.

Also I have a question if anyone could answer, the bad rotor had a huge dent in it, it looked like someone shot it with a gun, I was wondering what would cause this?? Is the impact of it hitting an apex seal after it pops that powerful?

KansasCityREPU

iTrader: (9)

Post pics of the bad rotor please.

Sir Surr

This one's that weird dent

Here's where the broken apex seal was

Here's the housing from the good rotor that had the chrome missing

KansasCityREPU

iTrader: (9)

Wow - All those parts are toast.