I need help with my '89 (early) xjs…will not start–have decent spark ,good fuel to rail and believe the ECU may be at fault. First, where does the vacuum line (one for the ecu) attach to the engine? It possibly could be severed or not even attached. I’m not sure what it’s roll is and perhaps my non-start problem. I just cleaned the plugs (they were black) and I think not firing through this whole Ideal…
It’s a start… Thanks, Ivan (Sloth)
Hi Sloth,
The vacuum line is attached to the bottom of the ECU. The car will still run without it connected, however it will not burn the right mixture of fuel.
The vacuum line attaches to a metal line under the boot and then traverses to the front of the firewall near the transmission tunnel.
Regarding your no start condition, it could be many things, just go back to the basics. 