potterpan

Ok, so I bought a 79 rx7 in non running condition, first mistake. Anyway I got it running after several issues. Fuel pump was bad so I replaced it with a universal one that works great. I also put the newer electronic ignition in because I hate points and gave the carb a thorough cleaning along with new gasket set, in other words rebuilt. I also removed all the smog pump and plumbing. I started the car and after the smoke cleared it ran great. Honestly I think you could have balanced a nickel on the air cleaner. Revved real smooth and fast. I then drove it up by my home so give the car a good wash and wax. That's when it hit the fan. Sitting there the idle became very rough and I had to baby the pedal to keep it running. It was warmed up at this time and not overheating. Then it quite running and I could not restart it. The next day I tried to restart it and it took alot of cranking but started. It ran rough and didn't rev smooth at all. Almost like it was only running on one rotor. I checked the timing, its right on. I cannot find the issue. Anyone else have a problem like this? I'm at the point that I think my engine is shot. Mainly because nothing else seems wrong. But to go wrong so fast?

Aaron Cake

iTrader: (1)

To eliminate the engine as a cause, see http://www.aaroncake.net/rx-7/blown.htm

But since you bought the car in non-running condition, and it was presumably sitting, an engine failure is a real possibility.

potterpan

That is exactly what I have been looking for. I will run some of the tests it calls for today. Thanks.

potterpan

Alright, I compression tested the engine and the front rotor gave me 75psi three times and the rear gave me 90psi twice and 100psi once. So I am guessing its time to rebuild it. I got it running again but it smoke real bad on start up. Once the choke was off it went back to running real good. And I thought, maybe its not to bad but when I revved it up to 4 thousand it smoked real real bad and then would not idle again and quite and would not restart so I just closed the hood. So its shot right.

IanS

iTrader: (4)

Maybe maybe not. Depends on how long it was sitting really. Could be that your new fuel pump is making too much pressure. You only need ~3 psi for stock carb whereas MOST universal external pumps run around 7. This could be where some if not most of your smoke is coming from.

potterpan

I do have a fuel pressure regulator I can put on to find out. I guess I figure since it recirculates the fuel from the tank to carb and back the psi would not be a problem. So far the fuel stays centered in the sight glass. But I will try the regulator, cant hurt.

potterpan

I put in the fuel pressure regulator and set it to 3psi with no improvement. Engine still runs poor and smokes really bad when revved. I just cant imagine something smoking that bad being good. I have another engine but am unsure of condition. I may try to get a compression test on it and maybe swap it in. Otherwise I am in the market for a good engine or a rebuild kit. The worst part is explaining to my wife why its going to cost more. lol.

Kentetsu

What color is the smoke? If the smoke is white, then it is probably coolant. If so, then I have had luck with Alumaseal (get this kind, nothing with copper), just dumped it into the radiator and after about a half hour the motor was fine. That was about 8,000 miles ago.

potterpan

It is white smoke but also smells very gassy. Does not smell like antifreeze. I thought that to. Once it starts and runs for about 30 seconds it no longer smokes until revved up to 4k. I will try that tomorrow though.

potterpan

Ok, now its running somewhat better but its still not perfect. I will just have to keep tuning it. The smoke had a big reduction in density today after putting in alumaseal yesterday. My idle is around 900 and gets a choppy if I turn it down from there. I have read that the breather on the fill tube can cause smoke. Looks like mine goes into some sort of diaphram housing. What if I hook that directly to the carb?

Kentetsu

Check out the "how to tune your idle" writeup over at Sterling's site:

www.sterlingmetalworks.com

Probably a lot of other info you could use too. Good luck...