gta_knight

Hey guys.

Got an 87 Trans Am, 5.7 goodwrench crate motor. Everything is edelbrock up top. Edelbrock performer carb is only about a year old (fitted before I bought the car)

So I'm not really a carb guy. My last Trans Am was TPI so i havnt had to mess on with a carb much. Anyway to start the Car, even if its been running like 30 minutes prior you have to pump the pedal. If it's sat even just over night you have to pump the pedal forever. And it fires, sometimes it cuts back out and you have to pump the pedal another 10 times and it starts, once it's warmed up for a couple of minutes it runs great.

If I manually fill the top of the carb with some fuel it will fire off straight away and run fine as its got enough in there until the fuel pump takes over I guess.

It has no choke on it either. So im wondering what is out of whack. I've seen videos of guys starting their carb car with no choke that's been sat for a month and they press the pedal once and it fires right up.

ironwill

First rule of troubleshooting is to fix all the obvious stuff first. Either find or buy all the missing choke hardware and associated linkage and reinstall and correctly adjust it, or else buy a new carburetor.

Then see where you're at.

Aaron R.

Replies above are good advice. If the carb is almost new it is very unlikely to need new accelerator pump though.

You probably have more than one problem, so as stated above fix the obvious known stuff first (choke). Next step is start google searching and read the Edelbrock carb manual cover to cover until you understand how the carb works, then tune it properly. You may still be left with minor issues but do the above and you will figure it all out. OR pay a mechanic lots of money to do it all for you.

My Edelbrock fires instantly on a cold start. I tap pedal once and crank it over. Starts and stays running instantly, but I have my choke and tune dialed in. The hot restart is a separate issue that I have given up on due to the inherent design of the car and carburetor. I have to hold pedal to floor and crank until it fires. I would go to modern fuel injection but those dont have the dependability or simplicity of this carb so I live with the minor imperfections I already have.

SIXT8

Hi, I’m a 62 year old guy who grew up on carbs. I usually have at least one carbureted car I drive regularly. The main problem driving with carbs on today’s alcohol mixed gas is that our fuel, with 10% alcohol, both evaporates and boils more quickly than back when carbs were coming from the factory. So after your car sits all night, the fuel bowl may be low or empty. When you park it after it’s warmed up, especially on a hot day, the fuel boils out. If you have an in-tank electric fuel pump regulated to the proper PSI, that’s about 90% of the fix needed for both cold and hot start. Pumping a carb 10+ times does nothing if there’s no fuel in the fuel bowl(s) and compounds the flooding of a hot engine.

Cold Start: With an electric fuel pump, turn the key to the ON position and wait 3-5 seconds (if you still have the factory ECU/oil pressure relay system then 3 seconds is all you get per key turn). This will put sufficient fuel in the bowl. Then depress the pedal ½ way and release. If it’s cold outside you may need to depress 1 full pedal and release. This pumps sufficient fuel into the manifold and sets the choke. If you have a mechanical pump, try cranking the engine for at least 10 seconds before touching the pedal. If you have a big gnarly cam and it’s really cold outside you may need 2 full depressions of the pedal. If you have a single plane intake you may need 2-3, but pumping the pedal like mad doesn’t accomplish anything.

Hot Start: First just turn the key to start without touching the pedal. If it does not start immediately, turn the key to start while slowly pushing the pedal to the floor. Hold it on the floor while cranking and release as soon as it starts. Hot staring has more variables. It is usually caused by the fuel from the carb bowl boiling/percolating which pushes fuel out of any/all of the fuel passage, into the intake, while you’re in the store. Depending on the length of time, temp outside, temp of engine, design of carb, it may start right up or require more AIR (not fuel) to start. So don’t pump the pedal in this situation, just one gentle opening of the throttle.

Other things that can help. Read any book on the theory of carburetion. The Edelbrock manual is a short read that covers the essentials. Tune your carb to your combination. Adjust the choke properly (Don’t remove it on a street car). Adjust your timing curve; initial, mechanical advance and vacuum advance. All three need to work right for your combination. Switch to an in-tank pump if you don’t already have one. Use a heat shield gasket under the carb. Duct cold air to the carb. Control under hood heat by using ceramic coated headers, removing splash shields from the A-Arm area of the fender well, hood louvers etc. Choose a carb like a Holley that has fuel bowls stuck on the ends. They are less effected by intake manifold temps.

I don’t post much but I hope this helps.

gta_knight

Great reply thanks. Well one thing i have done which has vastly helped is the idle mixture screws. Got that set with the highest vacuum possible and it starts a hell of a lot easier now. I let the car sit for about 4 hours after doing that then went back out to see if it started OK, which it did. Right off the key...never touched the pedal.

Next step is to install a choke as it doesnt have one. It's on a mechanical pump. The engine is a 350 goodwrench crate motor that was installed about 15 years ago. It's only done around 27k miles.

I checked the timing too while I was doing that and it's bang on 8 degrees which is fine as the car still has its ecu from what I was told.

tater

iTrader: (10)

I have had great luck with my Edelbrock carbs. Check to see if you are getting the squirt of fuel from the nozzle when you manually increase the accelerator. If not, it could be that there is no fuel in the bowls or bad accelerator pump....OR a stuck check ball under the accelerator pump nozzle. Under the accelerator nozzle there is a small brass weight and a check ball. It is there to help keep the reservoir filled with fuel. That way there is no hesitation with the squirter. The check ball can get stuck in the closed position and not let fuel enter going to the nozzle. If this is the case and if it continues to happen, the fix is to use a slightly larger check ball.

NoEmissions84TA

iTrader: (1)

The ECU is still functioning and you are using a manual carb?