83 rx7 with a 12a n\a. When I try to check my 1/4 mile times I can be floored through 1st and 2nd gears but once I get into 3rd gear it stumbles untill I let off to 3/4 peddle and I can't put more peddle on it because it will do the same thing... anythoughts on this. I was thinking rebuild the carb but I don't want to dig into that unless I have to.

 

Clogged fuel pickup, filter, or insufficient pump.

 

One other thing what are the pros and cons to eliminating some of the vacuum stuff off the carb set up, and eliminating the emissions smog pump.

 

Get it running correctly first before starting to remove stuff. This is something we hear on here all the time. "The car didn't run right so I removed xyz. Now it runs even worse." You need a baseline first.

 

Your float bowls are emptying out by the time you hit 3rd gear. We need info on your setup to determine what the problem is. If you are relatively stock Id say insufficient fuel which could be a bad fuel pump, clogged fuel filter or fuel sock, or the carburetor needs adjustment or rebuilding.

Have you played with the float levels?

 

I beleave the engine is stock ported,

 

I think you should revisit the thread you started on 5-27-13. There to find the answer.

 

I will be pulling the filter and also checking the tank for sludge soon. That's the plan as for now... and yeah I remeber the tread I visited before. It will be this weekend before I can get to it. Also I found that the carb rebuild has a higher float setting then the stock. This might be something to look into also.

 

Dont adjust the floats unless they are aftermarket. Even if you do adjust them bend the tabs in microscopic amounts and do a full test cycle on each adjustment monitoring the sight windows.

FYI... Some aftermarket kits are bad about having floats with pinhole leaks which can cause the float to soak in fuel and weigh it down causing all kinds of weirdness.

 

Well I figured I would toss an inline fuel gauge on this thing and see what I am getting from the fuel pump. not even 1psi but I have flow so I am thinking a new fuel pump is in order here. does that sound possible for a 3rd gear fuel drop. I would think that possibly by 3rd gear hammering on it with high rpm fuel demand the bowls are depleting and the pump is not keeping up... let me know if you disagree or agree. fuel pumps are not the cheapest and I will probably upgrade to a more aggressive pump if I have to replace this one.

 

How old are the parts in the secondary ignition system?
Plugs
wires
cap
rotor

Fuel System
Pump
Inline filters

Check the basics before heading into expensive repairs.

 

I have already looked at the Dizzy, Changed the plugs and wires. The problem only acts up once I am into the throttle hard and only once I hit 3rd gear. I let off the throttle a bit and engine kicks back strong but I am unable to put the peddle to the floor I have to keep it at about 3/4 of a peddle anymore and the engine cuts out like its starving for fuel

 

Did you ever clean the tank? If not, all else is folly.

 

Yeah the tank is clear of everything, in-fact I expected a little bit but there wasn't anything in there. someone must have cleaned it before me.

 

if the fuel filter is not stopped up then unhook the fuel line right before it goes to the carb and put it in a gallon jug. turn the switch on and see how much it fills up after 1 minute, it should be around a third full if the pump is good. if not then either there is a blockage from the tank to that point or the pump is just too old and weak.

 

OK here is a vid I just shop with my Ipod stuck to the side window, I hope this clears things up, I am really leaning towards a fuel pump issue...


Thanks for all the help everyone.

 

Yep, take off gas yank clear you inlets, spray some carb cleaner inside the fuel lines and blow it out. Make sure your outlet on your carb is flowing too. After you replaced your fuel pump.

 

Ok so I found out my old car had a brand new in-line fuel pump, so this is my plan. Take the new fuel pump and use it as a high pressure pump up in the engine bay and use the in-tank pump as a pick up pump until its final demise then I will have to modify the tank to work on the inline only and move it to the rear of the car... that sound like a good plan for now?

 

In-line pump will push 5-10psi and 25GPH that should be adequate for what I need right now.

 

If you have an in tank pump, somebody put it there. Mazda didn't. When you cleaned your tank did you remove the pickup and gauge sending unit?

 

Yes when I dropped the tank it was an intank pump... large oval type insert with a in it.... this does not surprise me with this car though. When I changed my U-joints out I found that my drive shaft was from what I could tell via the cap size a 76-78 cosmo or early RX. The u-joints that were on the car had been considerably smaller in size and cosmo's and early RX's used them. And I hade to change out the pinion also since the splins of my GSL drive shaft were diff. So I am findidng out quickly that someone has done some modifications to the car over its lifetime untill me.... Rats nest is next and stripping the carb.

 

here you go all better now and accelerates a bit better now also...


Click here

 

Just got my 2nd carb set up and stripped down. Can't wait to try this thing out. I set it for mechanical secondary's and removed all other not needed crap off the carb, also planning on removing the rats next and removing the a/c and air pump at the same time. also built a cold air intake cap for the carb... will unveil once I get everything on it and set.

more to come soon with pictures.