New water pump, new manifold gasket. new starter motor, new coils, breakers checked. nice sparks from the plugs, no compression faults. new rotary fuel pump (before it was a diaphragm pump on mine (?)). Well, battery is average but holds better with the new starter which makes the engine cranking faster. But, no way to start.
Well, to be exact, sometimes it starts. Then it works great. No smoke once it's warmed up, very stable idle, smooth and responsive engine... but I don't dare use it for any trip where I have to stop the engine, because I'm convinced it won't start again. What could the matter in your opinion?

 

things you can check:

1. water seals
2. compression

 

Flooding?

When you're trying to start it and it won't fire up, pull the spark plugs and check if they're wet. If so, then it's getting flooded.

You didn't mention if you had replaced the spark plugs, plug wires, dist cap and rotor. If not, that's a good idea. Even if the spark *looks* strong when the plugs are out, that's no guarantee of the ability to generate spark when surrounded by compressed air/fuel mix.

But if it is flooding the best recommendation I can give is new battery cables. They're easy to make and don't cost a lot, but they make a HUGE difference in cranking speed. Cranking at 300rpm after new battery cables I never have flooding issues. Cranking at 250rpm or lower on the stock cables and I'd occasionally have starting issues.

The stock cables tend to corrode inside over time, and they weren't exactly oversized to begin with. Go a size larger, copper cables and connectors. Have the battery tested.

If your cranking speed is good and your ignition is strong you should have a MUCH easier time starting. The only other thing I could think of, but only after you've done the above, is some kind of carb issue.

If the plugs are never wet, then maybe you have the opposite problem from flooding - maybe your carb's accelerator pump isn't working well. So when you pump the gas pedal a few times before/during starting you don't get the squirt of gas that helps it catch and get going. Grab a carb rebuild kit and the carb manual off foxed.ca. Don't adjust the floats (they're factory set and it's a royal pain to get them back to the right spot if you change them) and reuse the stock needles and seats since the ones in the rebuild kits are notorious for being shitty and sticking.
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Good luck!

Jon

 

That's a good point. There's no easy way to check the water seals without opening up the engine but if it blows white smoke on startup and you have to keep topping up the coolant those can be signs that one of your water jacket o-rings is blown and leaking into the combustion chamber. That is possible but in my mind it's not quite as likely as the other stuff, and since it would take a full engine rebuild to fix you might as well try all the other stuff first.

 

You can check the coolant seal with this tester. https://www.pineappleracing.com/cool...estercspt.aspx. You'll' need to remove the water pump housing and exhaust manifold. You're checking if water is making into the combustion chamber. I'd only check if there was a visible issue like sweet coolant smell/white smoke in the exhaust or the rad getting pressurized and being push through the overflow. Otherwise, I would not bother.

 

well, these days it's not as hard to do as it once was. KansasCityREPU posted a tool that makes it fairly easy today. no more having to pull the engine apart to "find out" or, in the case of freshly built engine, waiting for it run before you find out.

as for the likelihood of it being the water seals, you're probably right. there are probably other things that are more likely. however, i saw this part:

and it immediately brought me back to a time when i had to drive around on a bad coolant seal. it was pretty much just like he described. the only piece really missing is having to add coolant every few days. i also don't really remember mine smoking too much, but it may have. it was a long time ago.

so i threw it out there. if i'm right, great (not really great for him), and if i'm wrong, even better.

 

But I have no over-pressurized radiator, no coolant smell nor white smoke at exhaust. Plugs are not wet, but the thing drains my battery high speed. Sometimes starter turns fast, other times lower. I don't know where to point the issue. Could it come from some wiring? (My plugs connectors are as old as the engine)

 

Battery or alternator.

 

I think something goes wrong with the ignition system. I've changed for a new battery, but issue still occurs. The other day (with the old battery) after cleaning the ground wires, the car started right up, I let the engine warm up and it ran perfectly smoothly. Since then, no start at all. I expect to change breaker points to check if there is some change. By the way, does someone know about electronic (dual circuit possibly) breaker points kit to adapt on those RX non electronic systems.(For Mitsubishi distributor specifically designed for Mazda Wankel engines)?

 

Well, so much time wasted, because a supplier sold me two different new breaker points. Since my previous message, the car starts instantly, and the engine turns impeccably. Of course I've bought a new battery, I've also wrapped the cables to the terminals with copper wire for better contact, but above all I've put my old breaker points back in. Now that I've said it, I hope the car will continue to start, so as not to contradict me. I'm still looking for a compatible electronic breaker points kit, which should relieve the ignition process.

 

By the way, can anyone tell me the dimensions and material of the o-rings
of the intake manifold. The ones I've put on deform quickly. Many thanks.

 

usually i start by checking the accelerator pump, look down the throats of the carb while stabbing the throttle, no fuel spray means it is never gonna wanna start.

when the accelerator pump starts going it may still work, sort of.

 

My question arises because at the time, all the joints were black. The black seals I put in recently suffered the same deformation as the old ones, but in much less time. I realised this when the car was running very well, but that the coolant was running out of the coolant reservoir. The issue is a leak with these intake manifold o-rings. I'm going to replace them with brown FKM seals (high temperature and fluid resistance). I think I've found the dimensions. I just wanted confirmation of the thickness/outside diameter/inside diameter.

 

The intake water o-rings would not cause a coolant in the reservoir.

 

If your reservoir is overflowing, that means its getting pressurized by something. Could be a coolant seal leak on the housings but not the ones on the intake. If those leak you just see coolant dripping out under the intake or boiling on the exhaust.

 

he said it isn't puffing out smoke and the plugs are dry, hence why i gave the simplest test of all to perform and takes 5 seconds. a dead accelerator will mean a no start/very difficult to start condition.


take it a step further and shoot it with starting fluid and see if it fires right up.


a simple faulty radiator cap will cause the reservoir to overflow, lets not jump to a blown motor just yet.

 

Aside the breaker points issue, I forgot to mention that I had to fix the ground cable that connects the battery and the starter. It was frayed. Since then, the engine starts quickly and runs nice.. Sometimes there is a "bang" of backfire, I think it’s because of advance at the ignition to adjust better, or the engine still too cold when I stop it.