NCross

iTrader: (18)

I just can't get this thing to run for crap. It will start up after lots of cranking and sputtering. It will sort of hold idle for a minute and then dies out, floods, fouls the plugs and then won't restart.

Old photo from the previous owner.


Webber carb, Racing Beat intake manifolds, Holley electric fuel pump, Holley fuel pressure regulator.

I try to adjust the carb screws and FP regulator, but sometimes the slightest touch makes it stall out. I have installed a cut off switch for the pump behind the driver seat. I have to use it to start the car up sometimes.

BTW... the car is not turbo. It has a Pacesetter manifold and 2 1/2 inch straight pipe to a Megan tip.

Jeezus

iTrader: (4)

What kind of Weber carburetor?

trochoid

iTrader: (6)

After you figure out what carb you have, including jets, etc., what is your fuel pressure and are you using as a fuel pressure gauge?

NCross

iTrader: (18)

45dcoe carb. No gauge as of yet. I know I need to get one, but I figured I could tune it to at least hold idle without one. I guess not...

When you look at the carb inlet after it's been running you can see fuel still dribbling out meaning fuel pressure is too high correct? I just don't know how to tune it honestly. I've never had a carbed car before.

I know how to tune the main idle cam screw. I'm guessing that turning the fuel pressure screw clockwise raises pressure? counter clockwise lowers? What do the 2 screws on the back of the carb where the intake manifold bolts to do?

Sorry if I sound stupid, but I'm foreign to the 12a.

trochoid

iTrader: (6)

Dribbling fuel is a good sign of too much pressure. When I had 12 psi going to the Mikuni, fuel was running out of the velocity stacks. You're correct on how the fpr works, but which one do you have? The screws at the base of each carb are the A/F mix screws, they are used to set and balance the carbs, that takes a bit of practice. You need to do 2 things, get a fuel pressure gauge and a book on tuning your Weber. You might find something on tuning online, I haven't really looked.

NCross

iTrader: (18)

It's a basic Holley FPR 0-9 PSI I believe?

Is it more accurate to tune the FPR while the car is running or off? Would you recommend waiting for the car to fully warm up?

Jeezus

iTrader: (4)

Get a FPR and a decent gauge on that! You will notice a huge improvement. Also, let us know the specs on the porting, jetting, and what turbo you are running. With this info we are better off with suggestions to your tuning, as to shooting a blank.

trochoid

iTrader: (6)

Holley makes 2 generic fprs, a 1-4 psi, part#12-804, and a 4-1/2 to 9 psi, part # 12-803. They don't have one that's 0-9 psi. Iirc, you need about 4.5 psi for the Weber, that's what I run on my dual DCDs. Another option is the Mallory 4309. It's range is 3 to 12 psi and has a boost reference port. It is also a return style regulator so you'll need to connect the return line. It's also pricier than the 25 buck Holley, running around 70-80 bucks.

NCross

iTrader: (18)

Sorry, it's the 4 1/2 - 9 PSI. So would that basically mean the screw needs to be turned all the way out? I believe it says it is preset to 7 PSI from the factory.

tigermack

iTrader: (5)

To adjust the fuel regulator, you don't need the car to be fully warmed up.

Jeezus

iTrader: (4)

I ran my OER (racing weber) at 2.5psi, it was happy around that. You will need a new regulator regardless since you are going turbo. It will need to be rising rate regulator with 1:1 fuel:lb of boost

1979rx-7

iTrader: (1)

Some people don't read other post's to well . To adjust that particular regulator you turn the screw in to reduce fuel pressure and you turn the screw out to increase . It's in that book It's just very brief and hard to find . From what I've read and from help of well known tuners on this site the fuel pressure should be 4.5 - 5 psi for that model Weber

NCross

iTrader: (18)

Matt, did you have the screw turned mostly inward or outward when you had it tuned? I messed with it and can't remember...

1979rx-7

iTrader: (1)

I had it turned in pretty far I had put my cousins MAC tools fuel pressure gauge on it and adj. it that way

NCross

iTrader: (18)

With the following being said, I am still getting a fuel gauge to properly tune it...

I tuned it by ear today and it will start and run pretty well. Cleaned the plugs, put the battery on a charger overnight. It still cuts out/sputters a tad above 3000RPM and it fidgets a little when you have very light throttle input. I'm guessing fuel pressure is still within 1/2 PSI what it should be.

Also... When you shut the car off the rotors will spin a bit and then stop, followed by a backfire. Just needs more tuning?