Building my car to NASA rules. I thought I had all my ducks in a row in regards to wiring but found the following rule:

3.6.10.5 Fuel Pump
"All the fuel pumps must only operate when the engine is running,
except during the starting process."

My car is going to run on carbs, so priming the system isn't a real concern and it will only be operating at ~3 psi.

How is everyone wiring theirs up to meet this rule? This thread http://www.specialstage.com/forums/showthread.php?t=36627 has a couple guys saying they're just wiring it up to a switch (which was my origional plan). Oil pressure switch to trigger a relay? I am trying to make this as simple and reliable as possible (was hoping to ditch a relay all together)

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-Jason

Wire it to a switch for now. The fuel pump rules are being revised.

When the fuck else are fuel pumps running EXCEPT when the car is running or starting?

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Gone fishing

david amor Wrote:
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> When the fuck else are fuel pumps running EXCEPT
> when the car is running or starting?
>
> "this is certainly not a game for flyweights or
> ping-pong players-all arguments to the contrary"
> -C.B.


When they are wired to a dash switch that can be left on . If a car crashes and the engine dies the fuel pump can still run, if a line was torn loose it can be an issue. This is typically an issue in older carbed cars that had a mechanical pump stock.

heymagic Wrote:
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> Wire it to a switch for now. The fuel pump rules
> are being revised.

Switch it is. Thanks Gene

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-Jason

Jason,

Although not technicly leagal I like the three way switch idea. Switch up, the pumps are on with the ignition, Middle position, the pumps are off. Down, the pumps are on continuosly. This set up in conjunction with a second switch to select between pumps is really nice.

Robert.

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Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

Can you not just wire the fuel pumps into the ignition? (no i'm not going to read the NASA rules!)

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Gone fishing

david amor Wrote:
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> Can you not just wire the fuel pumps into the
> ignition? (no i'm not going to read the NASA
> rules!)
>
> "this is certainly not a game for flyweights or
> ping-pong players-all arguments to the contrary"
> -C.B.


I copied word for word the NASA rules above - but no this isn't any better than wiring it straight to a switch.

Think about it for a minute - you turn the ignition on and the fuel pump turns on. If you kill the engine - is the ignition still on? yes which means the fuel pump is still on. You would need to turn the key "off" for the fuel pump to stop. Same for straight to a switch, it will always be on unless you turn the "switch" off.

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-Jason

Most EFI cars are wired so that the pump runs for 5 sec. or so when you hit the ON position on the key to pressurize the system. Then they run in Start position and as long as the engine is running. IF the engine stops running they typically shut off within 5 sec. of the engine dying.

That's the way most Bosch stuff is and that's the way my Motecs are programmed. I also run both pumps thru console switches so I can select pumps, but I usually leave those 2 switches on and let the Motec handle the pumps. Easier.

If for some reason I want to override the Motec, I can switch the pumps off.

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Lurch
Eric Burmeister
The west coast...of Michigan

Bumping this back up since the new 2010 NRS rules came out with the same wording... and I'm just now getting to the fuel pump wiring.


Gene - still ok to wire it to a dash switch?

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-Jason

I used the stock VW system that has relay that looks for HAL signal off the distributor to power my carb fuel pump. I had an option of turning the pump off by hand at a switch but the pump only ran if the motor was spinning and sending HAL signal to this relay.

The Relay is located on the fuse panel under and to the left of the steering column. The Bentley book shows a good diagram of how it is wired. Simple and safe.

I also wired an override circuit after this relay failed on me at the start of Doo Wops a few years back, so I could make the pump run but I rather not have the pump running when the car is upside down in a ditch with me in it... so that was left off most of the time.

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In the long run reality always wins.

Thanks Derek - Only problem is I'm not going to run a distributor for ignition - going with a magnetic crank wheel/sensor. All the oem wires are gone except lights, starting, wipers and a heater. Plus if I remember correctly the MK3 brings the hall wiring into the ecu first (which is long gone).

If direct to a switch is no good, I'll just pick up a oil pressure switch to cut the fuel pump when there's no oil pressure like this: http://www.summitracing.com/parts/HLY-12-810/

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-Jason

Jason,
Not quite sure what happened to the rules thing with NRS this year. We just never got around to getting everyone together for a meeting.

Anyway...just use an oil lite pressure switch for a ground point and add a relay. Use a switch to power the relay and I would add a 2nd switch to ground the relay if the pressure switch failed.

What are you running for an ECU? If your ignition system is smart enough to control multiple coils based on crank wheel sensors... then it's gotta be smart enough to turn the fuel pump on/off.

Thanks Gene - yeah I'll just switch the ground - a bit easier than that fancy holley piece that could be easier to fail.



dtompsett Wrote:
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> What are you running for an ECU? If your ignition
> system is smart enough to control multiple coils
> based on crank wheel sensors... then it's gotta be
> smart enough to turn the fuel pump on/off.

Electromotive XDI. A quick look through didn't show anything to do it, but I might have missed something.

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-Jason