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Old 02-28-2009, 06:34 PM
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Need Help with EFI to Carb Conversion

I hope I am posting in the right section. I need some help with a project.

I have a 98 Z28 with LS7 block based 427. I am taking off the FAST intake setup and going to a Demon carb and Edelbrock intake. It came with a MSD ignition/timing controler. I am bypassing the ignition and fuel injection harness, but want to leave the factory computer for other functions. I installed a "Race Pumps" fuel pressure regulator designed for use with an efi pump and carb. The (racetronics)pump is fairly new

After setting everything up the fuel pump seems to quit pumping after intial startup. When I turn the key on. The fuel pump initializes and the pressure gage reads correctly, then goes down quickly. Then the carb will run out of gas in few minutes and the engine shuts down. I can turn the switch off and back on the it does the same thing.

Also the cooling fans do not come on.

I am not sure what to do about the pump, but I guess I can put a manual switch on the fans.

Any help would be greatly apprecated.

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Old 02-28-2009, 09:34 PM
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Is the crank sensor still hooked up to the factory wiring or does it just plug into the edelbrock box? The fuel pump will turn off if it doesn't pickup an rpm signal. I dont know how the conversion wires it but that may be your problem.
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Old 02-28-2009, 09:53 PM
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The crank sensor and the cam sensor are connected to the msd box.

I did not know that the pump requires a rpm signal. Thanks! There is a tach wire coming from the msd harness, but that is for the tachometer. Do you have any ideas for a work around?
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Old 02-28-2009, 10:33 PM
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Maybe you can split the crank signal by getting a female connector at the parts store or even a dealer. something like this should work but my paint skills aren't very good.
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Old 03-01-2009, 09:27 AM
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Quote:
Originally Posted by 1969NovaSS
Maybe you can split the crank signal by getting a female connector at the parts store or even a dealer. something like this should work but my paint skills aren't very good.
Sounds like a good idea. I will give it a try!
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Old 03-01-2009, 03:51 PM
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To give you an update, I made a connector and tied the crank sensor output into the stock PCM crank sensor connector, and everything works. Fuel, tach, etc.

Now it seems my Race Pumps fuel pressure regulator cannot handle the pressure from the pump. It is designed to do just that, but I may have to put two regulators in line. I don't want to change my pump out unless I have to. I think I will give Race Pumps a call tomorrow concerning the regulator.

Thanks for pointing me in the right direction.

Ira
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