Sniper trouble?

[Falcondriver]

I have a small block 427 from Blue Print engines with a Holly Sniper EFI. When I ordered my MK4 kit from FF i told them I was going with an EFI system on my motor. They sold me all the parts for the system. Fuel pump, filter, and regulator. Assembly went well car completed a year ago. Have driven 1600 trouble free miles since. When I turn the ignition key on I can hear the fuel pump run and the engine starts right up. Now when I shut the engine down after bringing it up to temp and turn the engine off if I wait more that 1 minute, I have timed this numerous times, the fuel pump will not come on and, of course, the engine won't start. Sometimes after 20 or 30 minutes the fuel pump will come on, but sometimes I have to wait 24 hours.
Installed new fuel pump relay, no change in this behavior. Once the engine is running I can drive for hours with no failure until I shut down.

I'm stumped.

[John Ibele]

I guess I'd run it until hot, then get it up on jack stands. Turn the key and (assuming fuel pump is not running), check V at the pump, and if nothing there, then at the relay. That should tell you whether the pump is getting the juice it needs, and whether you need to replace the pump or get on the horn with Holley. There isn't much in the Sniper installation manual about what conditions will cause the Sniper to not fire the fuel pump. There is something about matching the Sniper setting for fuel pressure so it matches your pump, but I'm assuming you've done that.

[Railroad]

Do not know much about Sniper, other than trouble.
If it reads fuel pressure, it might not let pump start, until fuel pressure goes down below hobbs switch setting.
You can bleed the fuel pressure off, if you have a schrader valve somewhere on the fuel rails.
Good luck,
I had a Projection Holley kit that injectors started leaking after shut down. It was hard to start if it sat for more than 15 minutes or so. After a long setting the gas evaporated and started right up.
I ran a heavy dose of injector cleaner and cured it.

[Norm B]

If the above suggestion doesn’t find the problem, set it up ahead of time so that you can ground the trigger side of the relay manually. This is the circuit that the Sniper uses to control the fuel pump. If the fuel pump will run manually grounded but not when connected to the Sniper you have isolated it to the Sniper or wiring between it and the relay.
I have had a bad fuel pump and a bad connection at the fuel pump cause exactly the same symptoms as you describe.

Norm

[wrenchigor]

You say that the fuel pump relay was replaced but didn't state if the sniper controller was operating the relay. If you flip the relay over and check the relay terminals with a test light, you should be able to narrow down the issue. If you don't have your install sheet, source Holley for the wiring diagram.

[Papa]

Are you using the Sniper to control the pump? The Sniper harness has its own relay that turns power on to the pump wire. Is that the relay you have checked? Like others have said, be sure you are getting power at the pump. If you have power at the pump and it isn't coming on, replace the pump. If you don't have power at the pump, start tracing back to the Sniper. If the Sniper isn't providing the power to the pump, be sure your main Sniper power and grounds are coming directly off the battery.

[rich grsc]

I know this can be a bit confusing but the ECU doesn't provide power to the pump. The ECU controls the pump relay, opening and closing the relay. All power for the pump comes through the relay, acting as a switch.