Matthew Diaz

Hey guys, I just picked up a 1990 FC from a local guy, seemed like he knew what he was talking about on the outside, drove the car home with no issues whatever, parked the car overnight, 4 hours later cranks but doesn't start. I immediately assumed I flooded the car, but after doing the egi fuse trick, still no start. Jumped the car because it was 20~ degrees, doesn't seem to be the battery.

Upon further inspection this "rebuilt, street Port" motor seems to be a load of Bs, spark plugs were incorrect Bosch ones off what I believe was a 3 series, a dead coil, all of which were replaced with NGK OEM stuff. Now I have spark, cranks a bit faster, but still no start. Injectors have power as well.


I'm not sure what to check next. Very confused because the car started four times without fail during my test drive, warming up when I first saw it, driving home 15 miles, and to start it again. After that, this issue appeared within four hours.

insightful

compression test, if severely low(below 75psi) it means the engine used poor condition parts and is why it has flooded to the point of not starting. verify plug wires are going to the proper locations, L1 lower front plug, L2 lower rear, T1 top front, T2 top rear. make sure the tach is bouncing when cranking. add some oil to the leading plug holes and reinstall the plugs and turn the engine over while giving it very light throttle.

keep in mind the S5 has a cranking fuel cut feature, anything over 20% throttle will cut off the fuel pump and sometimes can cause more headaches than it alleviates when trying to start a flooded car.

did you replace the spark plugs with the proper NGK BUR7EQ leading/BUR9EQ trailings? you could have just one plug fouled that is causing it, i do not trust anything besides the copper core NGK plugs. even the platinums can foul much easier than the copper core plugs that the factory recommended. if the plugs come out sopping wet with fuel its definitely flooded and usually points to compression issues. however you could also have been suckered into a car that had failing coolant seals. coolant in the chambers will snuff out the spark and cause it to not want to start, but will start and run fine after running and warmed up but give you problems after you let it sit just once. was the car warm when you checked it and purchased it? it's always wise to check that the engine is cold before trusting a buyer so you can check both cold and warm starts.

Matthew Diaz

he started the car after I had already been waiting for him. And it warmed up each time at what seemed like an ordinary pace. Yes, I went with the copper NGKs but the part numbers i used to find it were 5777 and 6917, I believe those are the ones you mean though yes.


I didn't​know about the fuel cut feature, however and that may be why the deflood didn't work. I'll definitely try that and see if anything changes at all.

Also, the old plugs weren't soaked through, but they were bent completely out of shape. They weren't the NGKs or even the right ones for the car, they were Bosch plugs out of what looks like a BMW. What I find strange is that the motor ran okay on those out of place plugs, but won't start with these brand new plugs and wires.

insightful

yeah those would be the correct plugs.

Matthew Diaz

Just found that the old spark plugs out of a BMW were bent out of shape because the rotors were striking them. Probably destroyed the seals. That​ might explain how it had okay compression on the way home but suddenly disappeared. What's the course I take, rebuild or swap, right? Horrible news because I just bought the car and it's a rust free frame and trans is fine. My second utter failure of an fc purchase..

insightful

how about pull start and then drive it through the living room of the seller? probably what i'd do.

i thought the majority of these tools were gone from the rotary scene, i guess they're still out there jacking up cars and passing them around to unsuspecting buyers. putting plugs in one of these cars is about the simplest thing anyone can do on a car, and also the most destructive when not using common sense. i have seen your scenario before with piston engine plugs in these engines causing seal nicks, it's just a really dumb way to cause thousands of dollars of damage.

lduley

iTrader: (1)

Sorry to hear, when it comes to what to do next is up to you. You could be looking at new housings and rotors depending on what happened inside.

One thing you could do is take the exhaust manifold off and take a visual look at the apex seals whether it be by eye, or rent a scope and take a peek, MAYBE you'll get lucky and won't have any major damage, but it doesn't sound like it, but this is something cheap you can do to give you a better idea on health of the engine, versus tearing it all apart to find out, choice is up to you

insightful

usually that sort of damage is localized to the apex seals alone, which is one good thing at least, but still requires a rebuild.

lduley

iTrader: (1)

Unless it was a 3 piece and snapped....but i should stop scaring him i guess lol

Matthew Diaz

Well, by all means I just wanna know how badly I got screwed. I'm gonna attempt a compression test before I go tearing the motor apart, but either way like you guys said, it's gonna need a rebuild. Would it be easier or cheaper to find another S5 motor that wasn't owned by a chimp and place that in there?

If the rotor housing are completely destroyed then I'm looking at a huge amount of money to rebuild the motor, and if he treated the motor that poorly, who knows what else is wrong with the rest of the car? The paint is awful and the interior is missing pieces, all things I would have put up with no issue with a running, decently healthy motor. But now I have to replace the typical suspension, brakes, tires, etc etc along with an entire new motor and maybe even transmission. I know cheap isn;t the way to go with anything, especially rotaries, but the budget just blew open with this discovery and now the dream is looking very far away indeed.

So if the housings and rotors haven't been utterly destroyed by the apex seals, then I might just have to do a simple rebuild, but if the housings are torn up I'm looking at another engine or at least new housings/rotors, right? I don't think the seals blew as I was driving, so hopefully there was no shrapnel bouncing around and destroying the insides...

lduley

iTrader: (1)

your going on the right track, but your feeling shot down, which is a normal feeling for one of these cars. They are almost 30 years old, EVERYTHING is going to be wore out unless you find someone who took care of it VERY well, which is rare, and if you did, you would've paid higher dollar for the car.

Take me for example, mine needs everything yours does, except mine runs (coolant seal, and OEM seals, getting tired) but I've wanted one of these for years, and I'm not letting it go because A) they are rare to find in michigan, B) its quite rust free, and I plan on NEVER driving it in the winter to help keep it that way.

Don't let it get you down, these cars sadly ARE a crapshot, but when you work on it, and fix it yourself then get to drive it, it will bring the Mazda Smile back on your face

The only way to know for sure what the engine will need is a tear down. I, honestly myself, would rather tear your engine apart and check it over and keep it going, reason being, YOU know whats in that engine, and YOU know the health of the engine. If you buy a used engine, your right back to where you are now. NOW, if you want to buy a used engine, tear it apart, rebuild it, then you can just engine swap in a couple days, then tear your old one apart for a rebuild, or if the parts are good sell them off, S5 parts are getting harder to find since their we're less of them, and alot of them are desired

insightful

yep, these cars should always be treated like a restoration project no matter how clean they may appear, at least you kind of knew how bad the car was neglected by the sight of it.

Matthew Diaz

Yeah, you guys are right about that. At least I bought the car and it needs this immediately. Would have sucked to daily it for a few weeks and fall in love with it and then have it explode on me lol. I bought one because I'm in a place now where I don't NEED a car every day but I want one, but I wanted to get something I've always loved instead of some ordinary beater. It's over at my friend's house now, this weekend we might do a tear down and find out how bad the damage is. In our cleaning of the interior, though we found a thing that appears to be an ecu. I have no pictures right now on my phone but it's a Denso (egi, maybe) box. Looks very important but it was stored away in the bin underneath some spare racing beat parts. A bad/faulty computer would definitely cause a no start, right? This new development has us scratching our heads..

lduley

iTrader: (1)

It wouldn't of let you drive it home either, so i doubt its your problem

Matthew Diaz

So, good news, motor is still in decent shape. It turns out the wiring on the fuel pump was really wonky and the fuel pump itself is going. I plan on ordering an OEM one from Rock Auto, but there's electric and mechanical pumps available. Which did my car come with originally, and should I choose one over the other?

lduley

iTrader: (1)

NO rx7 came with a mechanical pump, even 1st gens had electric.....honestly I don't know of any rotary that had a mechanical pump.....maybe the 10a?

liquidusculade

iTrader: (1)

Glad you found an easy fix. An electrical pump is what you need. I would also check fuses, sometimes oxidation can build up and cause issues if they havent been removed in 30 years or so...

Let us know how it turns out.