So I've been working on my mazda for about 3 months now, we've completely rebuilt the carb, put a brand new fuel pump, all new lines, even got a pressure monitor for it. So the car gets about 3-3.5 psi into the carb, I can clearly see fuel going into the carb yet it will not start without spraying starter fluid into it? I don't get it... And once I get it started the damn thing dies unless you sit on the throttle and keep it idling at around 2.5-3k rpms.. I can't seem to figure out why it wont start.. Help please!

 

sounds like the carb still has a restriction somewhere.

 

What do you mean by restriction? What could it be?

 

have you confirmed there are no vacuum leaks?

where is the fuel in the sight glasses?

where is the timing?

 

I can't confirm as I honestly don't know if there are any, I haven't seen any or felt any but I'm not sure.. And the other two questions you asked I haven't a clue what those even are.. Can you explain and I can try to answer?

 

well, start with those things ....

1. arm yourself with a FSM and/or Haynes manual

2. vacuum should be self-explanatory, but in the event that it's not, you're going to be looking for any where that the intake tract is open to atmosphere other than where it should be, which is at the throttles. there should be vacuum diagrams here on the board, but definitely in the shop manuals.

3. on the sides of the carburetor should be some little glass windows. you should remember them from rebuilding the carbie. where is the level of fuel in them?

4. timing is little involved, so i'll just ask this first: did you loosen, adjust or remove the distributor since you started messing with the car? it will be hard to check it since the car won't idle on it's own, but you can reset it per the instructions in the manual.

in the event that you never touched the distributor before: i don't know what the car did before you pulled the carb for a rebuild 3 months ago. presumably, it was not running right. so i would say work on the intake and carb issues first before messing with the timing at all.

you will probably get more focused and detailed carburetor input as the thread goes on from people smarter than me.

 

Something I forgot to mention, when the car idles, I have to have the choke engaged or it dies out, it won't idle below 2.5k rpm or else it just dies.

 

As for the Vacuum leaks, I can't seem to find any, all of the hoses we replaced with brand new ones about a week ago and there is no leak from what I can determine. As for the glass, there is no fuel in them now, however when the car is running they sit about half way full, we put an aftermarket fuel pump on it so it has a regulator to control the flow not to exceed 3.5 psi. And as far as the distributor goes, no we haven't touched it at all. Before we pulled the carb off the car ran, but not much better. I'd still have to prime the carb with starter fluid and run it on choke untill the engine warmed up, but not it doesn't even want to do that. When disengaging the choke the engine literally dies, regardless of rpm.. It's the damnedest thing.

 

this may be obvious, but have you been using the adjustment screws since putting it back on?

 

Yes we've been tinkering with them back and forth.

 

do they make any difference in any way - whether better or worse?

 

initially they did. But, we got them adjusted just right and now no they dont change anything.

 

well, i have to say it still sounds like it's probably a vacuum leak to me.

however, there are some other ideas to explore in this thread too: https://www.rx7club.com/1st-generati...-choke-676232/

 

Thanks for the help. I will keep looking and post a video of the car running and starting when I get to it probably be tomorrow.

 

So as promised here are the videos of the car starting and idling, I checked for any vacuum leaks and couldn't find any perhaps these with help these will help shed some light on the subject the first link I'm going to post is of the vehicle idling without the choke engaged it's pretty bizarre. Check it out.

 

This second link is of the vehicle upon start with backfire for a reason I don't know why.

 

I would guess there is blockage in the idle circuit. It'll run above 2k rpm because at that point, you are running on the main circuit. When you rebuilt the carb, did you remove each jet individually and spray carb cleaner through it and the hole it came out of? If you removed all the jets and cleaned them all at once, you may have switched up one or two.

Since the problem is the idle circuit, I would carefully inspect #94 on this diagram:






Remove the jet. Use the "coffee straw" on your can of carb cleaner to shoot some cleaner through it. Then spray more down into the hole it came out of.