y2kz3

My 1989 RX7 n/a has only 59,000 miles and immaculate maintenance. My mechanic at the dealership checked everything and nothing is wrong, but the car still has a random hard start (totally random, not related to temerature or last time driven at all). Random is sometimes once a week, and sometimes 3 times in a day. There is no pattern in any weather or starting conditions.

The SOLUTION I found was to use the manual's suggestion for a flooded car, foot all the way down on the gas while starting, which doesn't give it any gas according to the shop manual, but will clear fuel from a flooded engine (How, I don't know). The car is not flooded, but I used this method one day out of desperation. The car starts right up with no hesitation this way, and idles and runs perfectly once started.

My mechanic has checked everything possible, and kept the car at Mazda for a week looking for any reason for a hard start. Since the engine is NOT flooded when there is a hard start (I don't give it any gas, it's not a leaky injector, not a bad fuel pump or fuel pressure, compression is great...) why does this cause my car to start right up? Exactly what is the car doing when you step all the way down on the gas that would help me start it, but doesn't give any gas? Could something be "sticking" ramdomly and this unsticks it?

I've got my solution, but now I'm just curious why this works. Anyone know why all these facts together would make sense? Knowing this trick a long time ago would have saved me some anxiety during MANY hard starts.

NZConvertible

If this method works, then chances are it is flooding. When the S5 ECU sees wide open throttle and a start signal at the same time, it cuts the injectors (i.e. no fuel at all). This combined with WOT allows air to be pumped through the engine and clear out excess fuel, and relubricates the seals so compression can build again.

Blowtus

sounds like very mild flooding. does it sound any different when it's taking longer to start? could be anything to do with the idle circuit not adding enough air in on startup, when my bac valve wire came loose it'd flood damn near every time.

thesatanicmechanic

I think you answered your own question with your post.

I can't think of any other late-model fuel injected car that gives tips in its OWNERS MANUAL on how to start it once it's flooded.

Your car is flooding.

Here's prolly why:

The fuel injectors are getting pretty old & not shutting all of the way. This allows gasoline to drip into your engine while shut down. If this were a Chevy Cavalier, you wouldn't notice it. BUT, in your 7, this raw fuel dissolves the oil film in your rotor housings, effectively washing away any cold cranking compression.

Find a garage with a motorvac machine & get your injectors cleaned. (I do it for 59.95) OR pull them out & send them to RC engineering for cleaning & blueprinting. When you get either done, screw in a new set of plugs. I don't care if you just replaced them last week. A new set will ensure gleeful starting since your old onse have been fuel soaked a bunch.

The alternative? A Civic Hybrid. That isn't pretty.

y2kz3

Thanks for the insight... this forum is GREAT! I'd have to agree it must be flodding based on the facts. I just wish the Mazda mechanic would tell me these things because I'm very specific when I speak with him.

The hard starts are VERY hard starts when they happen, so I understand why now. Now I understand what is happening so that it makes sense to me how a wide open throttle would allow fuel to clear, and that fuel could both reduce compression temporarily by degrading the oil seal, and would foul the plugs over time if this happens too often.

Thanks for the quick responses! My wife and I love this car and want to keep it for a long time. That was the only thing happening that I couldn't figure out. Again, this board is the best!