Weber Conversion Question

[rob 0]

just on fitting twin 40s on my 1.6 xu 309 and run into a problem. all plumbed and though i was ready to start but fuel pump dosnt work.

using standard pump with a regulator, i have removed the ecu and the injection loom. is their some wiring that needs to be altered? or do i need to refit the ecu and some wiring?

thanks Rob

[Rob Thomson 6]

My vague memory of how the standard (Jetronic) system works is this...

• The ignition and injection systems are virtually independent.
• Turning the key to P2 only directly activates the ignition system.
• The injection ECU (including EFi ancillaries) and fuel pump are activated (separately) by the tachyometric relay when it detects pulses from the ignition system, i.e. only once the engine is turned over. The tachyometric relay will switch-off the ECU and fuel pump if the engine stalls.

Therefore, you should be able to remove the ECU and other parts of the injection system without affecting the operation of the fuel pump as long as the ignition system and tachyometric relay are retained in their standard form. Have you got a bit too carried away with the wire-cutters?

 

I suppose you could connect the fuel pump to another feed (i.e. another circuit activated by the ignition switch at P2) but you really need to be a bit clever so that the fuel pump doesn't run continuously when the ignition's switched on, and is switched-off if the engine stalls (eg. when you stack it into a tree).

 

I hope that helps, but it's probably been 10 years since I was properly au fait with how these things work and I can't actually remember very much about yesterday.

 

Cheers, Rob.

[rob 0]

the relay and ignition have been left intack, i have not cut any wiring luckily, just removed the injection loom

[Miles 331 1 Cars]

That will be why, The fuel pump needs a relay, I'd use a red top pump thou as it's more of a reliable set up

[rob 0]

got it running, it turns out the ecu and wiring need to be fitted with the earths connected up. so ive trimmed down the loom so it all under the dash nice and neat, set the fuel pressure just need to get it on the rollers now

[Miles 331 1 Cars]

You only need 1 simple relay for the pump then you can ditch all of the ECU wiring, its not needed

[rob 0]

i know i did think about it but having enough trouble with the wiring as it is at the moment so didnt want to start messing about to much