I have a 1984 240 with Jetronic FI system. The problem is a no start condition
where the fuel pump will not run. To date I have done the following: 1. cleaned and tested the main fuse. 2. removed cleaned and tested fuses in panel 3. replaced fuel pump relay 4. jumped #5 and #7 terminals in fuse box and fuel pump activates 5. checked timing belt OK 6. checked harness connectors at firewall connection; some insulation deterioration, obvious damage repaired. 7. tried different fuel injection computer. The problem persists. What am I missing? Any suggestions would be appreciated.

Since the pumps run with fuses 5& 7 jumpered, see if it will start that way.

If it does start, your fuse jumper is replacing a failing Fuel Relay — or one that is not getting the needed voltage (Fuse 12 or 13) BL/R wire
or needed ground on BL/GN wire from ECU.

If it doesn't start with Fuel Relay bypassed and pumps running, suspect a no spark problem. This will, by default, prevent the Fuel Pump relay from energizing.

If you have a meter or test light, put it on the Fuel Relay ground terminal by "back-probing" the BL/GN wire at the harness plug. You should see voltage (thru the coil) with Key ON, then it should change to a ground condition (from the ECU) while cranking/running.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

I followed your suggestion, bypassed the relay, and still no start. I checked
for spark and there was none. The problem turned out to be moisture and corrosion inside the distributor. I cleaned the distributor shaft,rotor and cap and presto!!! problem solved. It is amazing sometimes how easy it is to develop 'tunnel vision'. Thanks for the advice it is much appreciated.

My list for 240 no-start:
check for timing belt breakage
fuel pump relay
25 amp fuse (83-88)
impulse sender (89-on) or Hall sender
wire at battery or fuel pump
fuel pump
power stage
89-on, suspect ECU

The only things I see are Hall sender, power stage and working fuel pump. Did you hot wire the fuel pump briefly?