78 camaro z28 starts and dies

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Old 08-18-2015, 06:01 PM
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Default 78 camaro z28 starts and dies

Couple months ago we put a new carb on it and would run, then it wouldn't start. Sprayed starter fluid in it and it would start up and die. Yesterday I replaced fuel pump, and still no luck. I pulled the hose going into the carp to see if I was getting any pressure and I was. I'm out of ideas. Check the fuses, relays, grounds? anything else I can look at?
 
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Old 08-18-2015, 07:07 PM
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Verify that the choke is working properly. Look down the carb intake and see if the squirters are spraying fuel when you quickly pull the throttle linkage fully open. If it runs on starter fuel and then dies, most likely it starving for fuel. You may also have a very weak spark that is not capable of lighting up gasoline. Starter fluid is much easier to light up than gasoline, with enough compression an engine on starter fluid will run with no spark and possibly damage itself.
 
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Old 08-19-2015, 09:49 AM
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Wonder about the power to the coil/distributor? Often happens if some wiring has been done, and it gets fed from the start circuit. It will fire, but when the key is released it dies. Turn the key to the "on" position, and make sure the positive wire to the HEI or coil has 12v. power.
 
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Old 08-20-2015, 03:42 AM
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x2 for the HEI wiring. For some stupid reason my car was dropping voltage to the distributor under higher idles, i ended up running direct power to the distributor through a fuse and a relay triggered by the stock ignition power wire. The lower voltage that i was getting from the ignition wire is more than enough to switch the relay. An easy way to check if this is your issue, take some alligator clips and run direct from the battery to your HEI, remember that if you do this, your key will no longer turn off the car and you will have to pull the clip in order to shut it off.

What do you have for fuel pressure? If you strictly pulled a hose off and looked to see flow that doesn't tell you anything. Flow isn't pressure, although I can't speak about fuel pumps, i have seen numerous hydraulic and chemical pumps that are more than capable of meeting specified flow but under pressure they die.

You need to get a gauge on your fuel system right before the carb and verify that you are in the 6.5-7 psi range.
 
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Old 08-20-2015, 11:06 AM
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Originally Posted by Sudstoy
x2 for the HEI wiring. For some stupid reason my car was dropping voltage to the distributor under higher idles, i ended up running direct power to the distributor through a fuse and a relay triggered by the stock ignition power wire. The lower voltage that i was getting from the ignition wire is more than enough to switch the relay. An easy way to check if this is your issue, take some alligator clips and run direct from the battery to your HEI, remember that if you do this, your key will no longer turn off the car and you will have to pull the clip in order to shut it off.

What do you have for fuel pressure? If you strictly pulled a hose off and looked to see flow that doesn't tell you anything. Flow isn't pressure, although I can't speak about fuel pumps, i have seen numerous hydraulic and chemical pumps that are more than capable of meeting specified flow but under pressure they die.

You need to get a gauge on your fuel system right before the carb and verify that you are in the 6.5-7 psi range.
6.5-7.0 psi can be an issue for many carbs. I've had carb flooding issues in that range, and I now run everything set to 5.5 psi max. Talked with Holley techs long ago, and they recommended not going over 6.0 psi on their carbs. It's more about flow (as you mentioned) than pressure; but you do need certain pressure behind that flow.
 
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Old 08-20-2015, 03:18 PM
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Since the engine was running for a couple months with a new carb, and now it's not, I don't see how it would be an ignition wiring issue unless a wire fell off or broke. But it does fire up with starting fluid, so he does have ignition. Sounds more like a carb problem to me... a sunk float, stuck needle/seat, clogged filter, or high float/flooding issue perhaps. What kind of carb is this?
 
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Old 08-30-2015, 07:58 PM
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a water bottle with a pin hole in the cap is just about the perfect way to test a carb hold the choke open and spray t it the engine will run if its a fuel issue it wont if its a spark issue i bet there was a fuel problem, the ethanol fuels like to algae (a green hue in aluminum and brass ) that will flake and cause clogging issues in the jets. will it start if you hold it at WOT?
 
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Old 09-02-2015, 08:49 AM
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As said, carb's only require volume to fill bowl as atmospheric pressure takes care of the rest.
Quick volume check of fuel pump - at idle, pump should fill a pint in 15 seconds.
Is carb set up correctly for choke use and does it function correctl;y through warm-up?
Is carb being operated correctly?
 
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Old 09-02-2015, 09:19 AM
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One post, and the guy hasn't logged back onto this site in 2 weeks. Guess he must have fixed it!
 
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Old 09-03-2015, 05:53 AM
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You're right, kind of hard in reading machine gray print on a black background.
Same with menu bar - white characters on a yellow stripe - hard to read.

Hopefully, he did get it fixed.
 
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