kenwood1609

iTrader: (1)

I just installed a Holley sniper TBI on my 89 formula. It was originally a 305 TBI car I have upgraded the fuel pump to a walbero 255. When I installed the unit I didn't use the supplied fuel pump wire because it already had the TBI originally but I'm thinking the fuel pump doesn't run enough to prime up to the 60 psi needed for the sniper because I usually have to cycle the key twice. Does anyone have any experience with this? Thanks all!!
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Schurkey

Seems reasonable. All the GM cars I know of that run higher fuel pressure also retain pressure at least for awhile. The TBI system is not designed to hold pressure, so it's building pressure from "0" each time it's started.

The ECM is responsible for the two-second prime cycle. Maybe there's a way to "tune" the ECM to provide a 4- or 5-second prime cycle.

'Course, the fuel pump should be running if the engine is being cranked by the starter motor. Long crank time before engine run is also associated with a failed fuel pump relay or relay harness. Does the fuel pump relay work without excess voltage drop?

kenwood1609

iTrader: (1)

The Holley comes with a fuel pump control wire so I guess what I was wondering is is I can just tap into the fuel pump relay under the hood and have the Holley sniper control the pump.

Abubaca

iTrader: (3)

Yes, you can trigger the relay with the Holley wire. I did that on my Holley HP. You can NOT POWER the relay with this wire.

kenwood1609

iTrader: (1)

​​​​​​Thank you

Gunreaper

So I am installing a holley sniper efi kit also on my 89 camaro. Where did you connect the blue fuel pump wire from the efi harness? Didnt want to run it all the way back to tank.

any other wiring info would be great!

thanks

Abubaca

iTrader: (3)

Unless the sniper kit is different, you can NOT power the pump with that wire. It's intended to switch on the relay and that's it. .....so find your fuel pump relay. It'll have 5 wires coming off it. A test lead, ground, 12v power IN to the relay, 12v power going OUT to the pump, and a switch wire which turns the relay on and off. That switched wire is what you want. Just cut that factory wire, and wire in the blue lead from the Holley. The Holley ECM will now command the relay on and off. Again, very important, that wire can only power the relay to turn on and off, it can NOT actually power the pump itself.

Gunreaper

Ok thanks!

what about a switched 12v source? Anywhere under hood to pick up a 12v switched source?

Abubaca

iTrader: (3)

There should be plenty under the dash in various places. You'll need a wiring diagram, but checking is easy with a multimeter. .....but are you looking for a switched, but HOT WHILE CRANKING source? It's different than a regular switched source as most go cold during cranking. The ECU specifically needs a switched source that stays HOT while cranking as obviously the ECU needs to keep power!

87cam305

The sniper harness has a fuel pump relay built in. so the blue wire runs directly to the pump.