rotor-motor

iTrader: (7)

Put swapped in another 12a into my 7 this weekend with a rotary engineering duel weber setup. Put a mr. Gasket fuel pump right after the fuel tank and run fuel through the stock steel line to a pressure regulator inside the engine compartment. From the regulator I split the lin up into 2 and run them to the carbs. Running 3 psi. Idles fine and drives ok carbs are slightly outa sync

I get on the highway and it pulls pretty good but after a few mins of cruising it starts to loose power and go wop wop wop. Feathering the peadal doesn't seem to help and holing it wide open pretty much kills the engine. I pull over for a few and it starts back up and drive ok for another few minutes and does it all over again.

I think that the fuel pump can't keep up with the carbs. Does this seem logical? What are some things I could test?

snivley whiplash

iTrader: (4)

that pump may not keep up with the fuel demands of the dual weber. I am using a mallory 4070m fuel pump the has been rewired to keep a good power supply and constant fuel delivery, as well as a good pressure regulator to keep the pressure constant. you will also need to up the fuel line diameter in the car to make sure the volume is enough to keep the bowl full at wide open throttle. my car has 85 gsl-se fuel lines which are 3/8 diameter as verse the 5/16 stock lines. this is very important to keep the carb feed and eliminate lean burn and engine demise. DO NOT drive it anymore until you upgrade the fuel system. just a small bit of advise, been there done that....not good. a 110 gph pump might be a better choice.
hope this helps.

Joe

rwatson5651

iTrader: (5)

Yea, that "wop wop wop" you are hearing is prob lean detonation, deadly to apex seals.
You need more fuel at a higher pressure, the webbers like about 4.5 psi.

rotor-motor

iTrader: (7)

out of curiosity I bypassed the pressure regulator and i'm not getting the problem i had before. i also took off the filter hats and was trying to adjust the idle, notice that fuel is dripping pretty good in the secondary of the rear most carb and not in the front one, this is causing my idle to be erratic, also since i bypassed my pressure regulator when i turn off the ignition/fuel pump, fuel keeps flowing into the carbs and pools up pretty good.

Snivley, what if i where to purchase another identical fuel pump and run two 5/16 lines to the carbs?

Kentetsu

It might be that the pump is capable of feeding those carbs, but the stock fuel filter won't pass enough fuel to keep it happy.

I split my line, installed two filters in parallel, and then rejoined the lines. This way, each filter only has to perform half duty. Here's a thread on it: https://www.rx7club.com/1st-generation-specific-1979-1985-18/dual-fuel-filter-mod-528445/

I should be around the house this weekend, just shoot me a PM if you want to come by.

P.S. This guy raced with me a couple of weeks ago, his 1st autocross (I'm pretty sure) and only placed 3 seconds behind me! I think I'm going to have a little competition this year.


.

Sgt Fox

iTrader: (3)

I have the dual webers on a 12A. This is what I run:
-Mr. Gasket 12S Micro Electric Fuel Pump
-Stock fuel filter (not full of particulate though)
-Stock fuel lines
-Holley Bypass fuel pressure regulator (bypass feeds back to stock return)

I run about 4.5 psi. Its probably not a bad idea to tear those carbs apart and clean them really well. Even if it doesn't solve your problem, it will make tuning much easier.

snivley whiplash

iTrader: (4)

rotor motor,
You are on the correct path, you just need more volume at 4.5 psi to feed the beast. also summit makes a large metal fuel filter that can flow lots of fuel. are you running a return style regulator? this also a must when doing large volume fuel pumps. A single 3/8 fuel line should feed the carbs ok with the advised set up above. also see the previous post.

rotor-motor

iTrader: (7)

Kentetsu, that was my first autox and it was a blast!! we'll have to ride out to martin on the 12th together.

Sgt Fox. love the setup! makes mine look like a rat rod lol
i'll have to get a pic of the regulator I have that came with the setup. it has a small nipple on it that had a vacuum line that ran int to the fuel line after the regulator, seemed like its how the psi gauge got its readings, maybe its a return? its just some cheap no name regulator.

so far from from all of your guys awesome input I plan on
-new fuel filter
-better regulator and run it at 4.5 psi
-figure out witch is the return line lol

also what is the nipple just below the oil filler neck, theres one on the neck its self and I have a vacuum line running from that to the rear carb as mentioned in the rotary engineering manual.

Kentetsu

If your fuel pressure regulator has a vacuum line running to it, then it must be a "rising rate" fpr meant for turbo applications (I think?)... I can imagine that would cause you some problems.

rotor-motor

iTrader: (7)

so i got my holly bypass style regulator in the mail yesterday and installed it today.

cant get the fuel pressure below 8psi and im leaking gas at the tank. i did remove the check valve when i installed my pump so im thinkiing the tank is getting pressurized and cant vent

rotor-motor

iTrader: (7)

Was able to get the pressure down to 4.5psi but there's still gas leaking from the top of the tank. Don't have a large enough gas can to drain the gas so I can't drop the tank at the moment, fml lol

rotor-motor

iTrader: (7)

said ef it and dropped the tank. found out the steel return line from the tank had a small hole from rust. packed on some j-b weld and crossing my fingers that seals it up

Kentetsu

Same thing I had to do with my tank, but mine was a huge hole. lol.

Keep in mind that with the Holley fpr, tightening the adjustment down is increasing the pressure. Backing the adjuster out reduces it. A lot of people get that wrong, just like I did at first.

Oh yeah, Kyle blew his motor and lost your number....