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Old 03-19-2010, 10:53 AM
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Fuel (pressure) or Spark problem?

Cars been running great. Broke it in - have driven it about 150 miles and now it wont stay running.
I can get it to start for about 10-15 seconds but intermittently. Other times it only sounds like it wants to start. Sounds like it runs fine when i have it running then it just dies out like it isnt getting fuel (or it gets too much fuel?), or bad spark.
My by-pass has a gauge installed on it and when i have the pump on its reading 9-10psi. When i crank on the motor it drops down to about 6-7 but only for a moment then jumps back up. Thought perhaps it was a spark issue. Replaced the spark plugs, no help. I installed a new coil, dist cap, rotor, ignition module, when the motor was built. The ignition box is a Mallory Hyfire VII's. I know im getting spark as its burning fuel but it wont stay running. Pulled the return line and blew it out thinking it was plugged. No help. Pulled apart the bypass and cleaned it, reinstalled. No help. Have new spark plug wires coming today that i will try. Checked my float levels and adjusted them - no help. Messed with the fuel/air screws no help. idle adjust screw only slightly helps and will allow me to start the car and it will idle for a few moments then die, if i try and give it any gas it just dies.
I thought for sure it would just be a fuel pressure issue but now that i think about it even with the fuel pump off the car wont start and stay running with just the fuel left in the bowls. Pulled my carb apart thinking i had a leaky needle or fuel was just constantly flowing into the intake. That didnt help. I havent adjusted valve lash since the car was first broke in guess i can try that. Could this be the ignition module gone bad?
454 .020 over 10:1 CR
230/230 @ .050 hyd flat tappet cam
1.7 rockers
stealth intake
Mallory ignition system/dizzy
750 BG Silver claw dp - no choke
BG HR250 fuel pump, -8AN feed line, inline BG fuel filer, BG diaphram by-pass /w -6AN return to hard line at tank. Tank is sumped.

Thanks for the help!

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Old 03-19-2010, 01:17 PM
richard stewart 3rd's Avatar
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I don't think it's a fuel problem, it would smell of a lean condition & probably knock (ping) when it quit running,
you've checked or replaced everything except the mallory system, try disconnecting everything except the dist.
& coil & see what happens.
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