Tachymetric Relay , What Does It Control?

[pugpete1108 62 1 Cars]

i have just finished rewiring my parts of my loom (lights etc.not engine managenment) and now i find that the fuel pump is not priming (bearing in mind there is no engine and no engine wiring) , is it to do with the engine not being in or is it something else?, it is irrelevant anyhow as the pump will be run from the ecu in the future, but was just wondering if it should be working now.

 

also i will be running emerald management in the future so was wondering if i can junk the tachymetric relay (the ecu will controll the fuel pump ,ignition etc..) .what does it actually run/controll?

[Jonmurgie 2]

Why are you trying to prime a fuel pump when there is no engine etc.?

[pugpete1108 62 1 Cars]

Why are you trying to prime a fuel pump when there is no engine etc.?

 

 

i'm wasn't specificily but i was checking the operation of the indicators hazard etc.with the ignition on (all the wiring was a mess) ,and just happened to notice there was no noise from the pump ,and thought i might have buggered it up

[t16ryan 1]

usually the pump only pumps on cranking not just with ignition on ? or am i wrong???? sure its when cranking triggers the fuel pump?

[pugpete1108 62 1 Cars]

usually the pump only pumps on cranking not just with ignition on ? or am i wrong???? sure its when cranking triggers the fuel pump?

 

 

that could be why then, and as there is no starter connected too nevermind just a thought.

 

relay anyone?

[B1ack_Mi16 67]

that could be why then, and as there is no starter connected too nevermind just a thought.

 

relay anyone?

 

On my 405 Mi16 the fuelpump is never priming before I start the engine.

Pump will not start before crank-sensor registers engine rotation.

[pug_ham 242 3 Cars]

On normal 205 Jetronic wiring if the starter isnt working correctly then the fuel pump will run after turning back from start as it has no indication that nothing isn't working but if all is well it will only run once the engine is started afaik. (solenoid disconnected etc)

 

If you are fitting an aftermarket management system then all of the original 205 system can be removed & the new ecu should have relays etc that control it. A tachymetric relay controls the fuel pump & injectors. Looking at the 205 wiring diagram I think the tachymetric relay has an ignition switched feed that is controlled by the coil once its started but it also has a feed from the starter solenoid wire which might takeover. Wire #32 is ignition switched closed & then either 46b or 112a changes to control when its running ( I'd say 112 as it shuts off the fuel pump when stalled but that doesn't explain why the fuel pump will run on when the starter doesn't work).

 

Either way what have you done to the wiring to effect the indicators etc when fitting the Emerald? They don't need touching to fit it afaik.

 

Graham.

[pugpete1108 62 1 Cars]

Either way what have you done to the wiring to effect the indicators etc when fitting the Emerald? They don't need touching to fit it afaik.

 

Graham.

 

 

i haven't done anything to the wiring apart from remove/replace alot of corroded terminals and dodgy wiring ,and generally tidied it all up on the passenger side of the bay . and i was just wondering if i could junk the relay thats all . i know the emerald has its own loom to control all the engine management and also the fuel pump/fan etc.

[pug_ham 242 3 Cars]

i was just wondering if i could junk the relay thats all .

I say yes. I removed it from my car when I swapped to the MP3.1 & afaik everyone that has fitted the Mi16 Motronic injection has also.

 

Graham.

[pugpete1108 62 1 Cars]

I say yes. I removed it from my car when I swapped to the MP3.1 & afaik everyone that has fitted the Mi16 Motronic injection has also.

 

Graham.

 

 

good good, what should i do, track all the wiring back and remove it that way?

i suppose i could remove all the wiring for the coil etc also?

[pug_ham 242 3 Cars]

If you are completely doing away with the Jetronic ecu & everything then simply follow remove the ecu loom & plug, the tachymetric relay will come out with it, all you need to remove (at least I did) are the wire for the fuel pump & I also used the ignition switched feed #32 from the relay plug. All the coil wiring etc is mixed with it but there are feeds for the coil & ignition amp in one of the multiplugs by the heater matrix.

 

I also used the original coil feed joined by the brown plug but find someone that has fitted the Emerald to their car as they'll probably be able to give more insight into exactly what to remove.

 

Graham.