RPM Relay - Fuel Priming

[ChrisS]

TheOriginalMrP Wrote:

NickT Wrote:I think Blimey Ben has ChrisS's solid state one. It would be good to get his feedback on it.

NickT

Hi Nick...... and everyone else.

Not sure about the RPM relay, but it's defo got the modified central locking box. I'm sure ChrisS will add if the relay has been modified.

The RPM relay was a standard green Volvo one,,,but there again I might have put one of the OEM black ones in from Dave H lol.

[Rich H]

NickT Wrote:Rich, with your electronic know how I am sure you can easily mod one that does initially run the fuel pump for a sec or two regardless which car it is in It would definately solve starting issues like in Dan Shanes fix.

I was interested to see if the prime thing works to a certain VIN number if the car ever had a wiring loom/ earth point change or not etc.

NickT

Another project for the list then By taking out a couple of components designed to stop the RPM relay from priming would certainly alter the behaviour though I couldn't say for sure whether it would be enough to get it to prime. The 555 timer chips are extremely sensitive to glitches on the trigger input of the chip. Any spurious spikes from pretty much anywhere when the ignition is switched on would cause the chip to false trigger.

Anyone who has a relay that primes, try unplugging the ignition amplifier module and see if that has an effect, I suspect it probably will - I'd try it myself, but.....

[NickT]

RichH Wrote:

NickT Wrote:Rich, with your electronic know how I am sure you can easily mod one that does initially run the fuel pump for a sec or two regardless which car it is in It would definately solve starting issues like in Dan Shanes fix.

I was interested to see if the prime thing works to a certain VIN number if the car ever had a wiring loom/ earth point change or not etc.

NickT

Another project for the list then By taking out a couple of components designed to stop the RPM relay from priming would certainly alter the behaviour though I couldn't say for sure whether it would be enough to get it to prime. The 555 timer chips are extremely sensitive to glitches on the trigger input of the chip. Any spurious spikes from pretty much anywhere when the ignition is switched on would cause the chip to false trigger.

Anyone who has a relay that primes, try unplugging the ignition amplifier module and see if that has an effect, I suspect it probably will - I'd try it myself, but.....

I will try this on my car Rich and let you know the results.

I thought something simple like a capacitor/resistor network on the positive supply side of the relay might be suitable:
http://www.the12volt.com/relays/page5.asp

NickT

[Dan6457]

Something very strange here. My car primed today for the first time ever....

[bozzzydmc]

Well looks like whatever you did 'fixed' it lol

[A Van]

Well..

Two days ago my car stopped priming for the first time.......

[bozzzydmc]

LOL... there hasnt been any parts swapping going on has there

[Dan6457]

The only thing I've done to my car since last time I used it is rebuild the whole thing :wink:

I've tried it since and its stopped priming now so I think it was just something weird while the car was coming back to life.