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Hello all, I just recently purchased an RX-7 FB GS and have been running into some issues since the day I got it. I bought it and it could only idle with the choke on so I figured I had a big vacuum leak due to the now removed rats nest(and all Associated things to be stripped from the carb and intake) or the idle circuit in the carburetor was plugged so I went ahead and rebuilt it with a fresh kit and made sure to leave out the needles and seats in the kit as I heard those are no good. After rebuilding the carb I went ahead and reattached it and I'm now dealing with a no start issue, I went ahead and started to try and deflood my engine as I figured it was probably full of fuel at this point so I went ahead and followed standard deflooding procedure but now my fuel pump won't come on when I turn the key and I'm at alittle bit of a loss for the now maybe dead fuel pump. After the flooding I was able to get compression again but obviously I won't be able to run the engine without a fuel pump, but for the sake of testing I can use starter fluid. What should I do to try to get the engine firing and pump going?
welcome - not being totally familiar with FAQ contents, my thoughts:
-pump: if wired correctly and has power, then it should be replaced.
-presume ignition is confirmed as far as spark
-only with an operating pump can you be sure fuel lines/tank are actually delivering fuel
-presume you dropped in a new fuel filter! (in front of rear driver wheel)
-need a strong battery, good cables. Seen a lot of no start and mystery electricals due to 'cables that look fine'
These are cheap to replace, and unless you know the PO has done this, then assume cables are waaaaaay past their due date and swap in a new set.
Likewise all the related ignition bits: wires, plugs, cap and rotor. Start with a clean slate of new everything...
Didn't have time to post earlier! Was able to get it to start after adding more ATF via the carb and cranking her longer. I was able to figure out that my temperature switch for the choke had shorted out and blew out the engine fuse. I replaced it with a spare and the pump came straight back on. But now she idles at 5 grand:-( but now instead of dying when the choke goes in she comes down to about 4 1/2. So I know my carb rebuild was a success as far as cleaning the idle circuit. I'm guessing that the carb spacer may be leaking or maybe the intake manifold gasket could be leaking air and contributing to the high idle
As far as what I have done to the car: rats nest removal with full emissions delete ( left shutter valve in place but capped nipples, used block plates for aab valve number 2 and hose behind carb, the finicky vacuum hose that usually cracks behind the intake / exhaust manifold has been capped as well) as well as a brake job, full brake fluid change, fuel filter/ clean fuel lines, and carb rebuild/(mostly complete) strip.
As far as what was already done: muffler delete, push button start, hot assist delete,
Last edited by Rx7FBguy; Jul 25, 2021 at 03:28 AM.
When I had a vac leak after carb rebuild it wanted to idle around 2000 rpm. 5000 is excessive. Are you sure the idle set screw is adjusted properly and the linkage isn't bound somewhere?
When I had a vac leak after carb rebuild it wanted to idle around 2000 rpm. 5000 is excessive. Are you sure the idle set screw is adjusted properly and the linkage isn't bound somewhere?
I am sure the idle screw has been adjusted correctly (was set before and does nothing to the idle right now)
I also heard that the idle speed screw has no effect on idles over 2000 RPM? I haven't had a chance to check out the linkage again since rebuild, will do that when I get home from work today. Anything I should be looking out for in specific?
Everything on the primary side should be closed when the car is turned off, and should open smoothly by hand (or gas pedal) when you move it. If the butterflies are open when the motor is off then either a cable is too tight (throttle, cruise or hot start cables) or something is assembled wrong on the little levers and rods. Check how they connect up to the choke flap. Note - the secondary won't really open by hand, as it's controlled by engine vac and load.
If everything looks good and moves smooth then maybe it is a vac leak. Check all nipples on the vac-plate under the carb, all potential openings on the manifold, etc.. What vac lines do you still have connected? Distributor advance, brake booster and oil tube breather?
Everything on the primary side should be closed when the car is turned off, and should open smoothly by hand (or gas pedal) when you move it. If the butterflies are open when the motor is off then either a cable is too tight (throttle, cruise or hot start cables) or something is assembled wrong on the little levers and rods. Check how they connect up to the choke flap. Note - the secondary won't really open by hand, as it's controlled by engine vac and load.
If everything looks good and moves smooth then maybe it is a vac leak. Check all nipples on the vac-plate under the carb, all potential openings on the manifold, etc.. What vac lines do you still have connected? Distributor advance, brake booster and oil tube breather?
I was only able to work on my 7 for a little while last night..... while I inspected the linkage I found the butterflies for the primaries open 1/16 to 1/8" and the cruise control cable wrapped up in the linkage (I just pulled out the cable and capped the vac line for now), and reinspected my vacuum lines (but didn't look at what was hooked up! Doh!) I sadly was not able to start her up because by the time I got to working on the 7 it was almost curfew. I will report back tonight with any findings.
The cruise control was sadly not the issue.... I will be diverting my attention to the carbs spacer gaskets I added and trying to set up with no added gaskets
Forum posts and replies are slow in the Summer. I like to think we're all out enjoying our cars. In the Fall, Winter, Spring you get more replies.
That being said, your picture isn't helping any. There are so many little bits on the stock Nikki linkage that it's hard to see what's going on there. Did you take before /after pics as you rebuilt the carb? I don't remember a rod-mod when I rebuilt my Nikki. I did the AP mod and deleted all emission stuff, and it worked fine. I converted to manual secondaries and it worked fine. But I took tons of pics before I pulled anything apart.
I don't mean to sound negative, but realize you are there and we are here. You have a hazy pic of one angle of a complicated carb linkage. And most of the experts are playing on the beach.
Does everything in the linkage(s) move how and when it should? Do you understand how the (overly complicated) choke works? Do you understand how the vac secondaries work? Are you sure you put all the linkage plates back on the shafts in the right order and have all the spacers and springs in the right places?
It's hard to diagnose these things over the keyboard so be patient and check your work. Many, many experts and Certified Mazda Techs here,.. be patient.
As I said, in the winter everybody is here typing because we can't play outside. In Summer the answers come slow.
check spark plugs. red insulator means not enough fuel. black means too much. and turn the engine over while the plugs are out and grounded to verify that you have spark, pull the fuel pump fuse while doing this. spark needs to be blue.
and you can check the spark's strength via the old school method. spark from the coils high tension lead should beable to jump about 1/4 inch body (ground). if you do this, don't lean or touch the car or you might get one hell of a shock.
doing all this will eliminate the possibility of it being a spark problem, or a fuel problem and you can re-concentrate on vacuum leaks being the problem.
rotaries can be finicky.
Last edited by midnight mechanic; Aug 4, 2021 at 03:22 AM.
You are completely right sir, I may have just been more than a little impatient and not considering others. on another note I was able to get her started and running semi alright! (Carb mixture was incredibly too lean, battery cables were shot, and spark plugs needed replacing, I still need to retune the carb as I hastily tuned it before the car could warm up properly leading to another no start condition). I tried moving her once I got her idling but she would die under load, I discovered the previous owner only replaced one front calipers and the other caliper was seized shut causing her to stall out after I gave her the juice.
I will verify my spark even after replacing them as soon as I can, and if I can get her to idle well enough I will also check the timing. The fuel pump and filter have both been replaced and the lines cleaned/purged so I highly doubt this was/is a fuel issue, but we will see as soon as I check her out. Does anybody know what size wrench I'll need to disconnect the brake line from the caliper?
Last edited by Rx7FBguy; Aug 5, 2021 at 03:38 PM.
Reason: Added a question
Forum posts and replies are slow in the Summer. I like to think we're all out enjoying our cars. In the Fall, Winter, Spring you get more replies.
That being said, your picture isn't helping any. There are so many little bits on the stock Nikki linkage that it's hard to see what's going on there. Did you take before /after pics as you rebuilt the carb? I don't remember a rod-mod when I rebuilt my Nikki. I did the AP mod and deleted all emission stuff, and it worked fine. I converted to manual secondaries and it worked fine. But I took tons of pics before I pulled anything apart.
I don't mean to sound negative, but realize you are there and we are here. You have a hazy pic of one angle of a complicated carb linkage. And most of the experts are playing on the beach.
Does everything in the linkage(s) move how and when it should? Do you understand how the (overly complicated) choke works? Do you understand how the vac secondaries work? Are you sure you put all the linkage plates back on the shafts in the right order and have all the spacers and springs in the right places?
It's hard to diagnose these things over the keyboard so be patient and check your work. Many, many experts and Certified Mazda Techs here,.. be patient.
As I said, in the winter everybody is here typing because we can't play outside. In Summer the answers come slow.
Thank you for the perspective! I really appreciate the time you have put in already
