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Fuel Pump Doesn't Run While Cranking

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Old 06-04-2007, 02:45 AM
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dustmark
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Default Fuel Pump Doesn't Run While Cranking

I am having a problem with the fuel pump not running while cranking the engine over. The relay seems to be okay because I can hear the pump kick on for a couple of seconds when the iginition is turned on and it will also run continously when grounding the fuel pump pin on the diagnostic port, but there is no fuel pressure when cranking. I am using Aeromotive rails, pump, and regulator. There are no fuel leaks in the system when the pump is running but it doesn't hold pressure when the pump shuts off either. The car started for the first time a week ago and then I discovered a break in the hard line and replaced the feed line with braidedto match the return and now it won't start anymore, I'm stumped any ideas would be greatly appreciated.
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Old 06-04-2007, 02:49 AM
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mattdel
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Default RE: Fuel Pump Doesn't Run While Cranking

TFI is bad
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Old 06-04-2007, 02:51 AM
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Default RE: Fuel Pump Doesn't Run While Cranking

I'm running all MSD for ignition and I have spark from the coil wire to ground. The TFI is brand spanking new, is there a way to test just the TFI?
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Old 06-04-2007, 03:03 AM
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iceman89gt
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Default RE: Fuel Pump Doesn't Run While Cranking

make sure the vent for the tank isnt smashed,kinked or damaged also.
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Old 06-04-2007, 03:07 AM
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dustmark
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Default RE: Fuel Pump Doesn't Run While Cranking

It's a drag race fuel cell with foam. The return line feeds in from the top and it's fine, the feed line from the sump is fine too. The other -8 outlet is plugged off and no leaks there. The fuel will flow just fine when the pump is running using the diagnostic port ground. The injectors don't have any fuel leaking from them under pressure and none of the fittings are leaking. I have teflon tape on the threads of the fuel pressure gauge and the vacuum line port.
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Old 06-04-2007, 03:14 AM
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mattdel
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Default RE: Fuel Pump Doesn't Run While Cranking

worry about the electrical part right now.
the TFI is your crank sensor..
check the green and the pink wire for output signal.
if your wiring isn't the same color, its the top post and the 3rd post down.
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Old 06-04-2007, 03:17 AM
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kdizzle711
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Default RE: Fuel Pump Doesn't Run While Cranking

I had this same problem after hiding the wires in my bay, and it was because I did not put the engine ground from the negative side of my battery back on.
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Old 06-04-2007, 03:21 AM
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dustmark
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Default RE: Fuel Pump Doesn't Run While Cranking

so what voltage am I looking for? The only info I've found on the TFI is to disconnect the SPOUT connector and test with the engine running which should be 4.2-8.4V and to check the ignition module connecter itself at terminal 6 and the SPOUT connector for a resistance of 5 ohms.
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Old 06-04-2007, 03:23 AM
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Default RE: Fuel Pump Doesn't Run While Cranking

I have the engine grounded to the shock tower right now and my next step is to run a ground from the engine all the way back to the battery in the trunk. Funny thing is it started just fine with no ground to the block a week ago.
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Old 06-04-2007, 03:25 AM
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mattdel
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Default RE: Fuel Pump Doesn't Run While Cranking

just stick a voltmeter into the wire and look for anything. if you dont have a crank signal it will stay 0v.

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