Fuel pump running constantly-with just Ign. on ?
11-06-2004, 05:23 PM
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Fuel pump running constantly-with just Ign. on ?
I had a look at a '92 GTS a friend is thinking of buying, the fuel pump runs all the time the ignition is on, with out the engine running ??? why ? how ?
I swapped the fuel pump relay over with another #53, still the same.
The wiring looks unmolested & it does not look like there is any alarm/immobiliser fitted.
Anybody any idears ?
I swapped the fuel pump relay over with another #53, still the same.
The wiring looks unmolested & it does not look like there is any alarm/immobiliser fitted.
Anybody any idears ?
11-06-2004, 08:18 PM
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1. Air leak in fuel line
2. Short cicuit in actual fuel pump motor
3. Second relay was bad (assuming first was bad also)
4. Pump motor receiving voltage from other than wired source (hot wire, ground loop, wierd hookup, gremlin).
Here what I would do:
1. Test fuel pump with all vehicle connections disconnected; apply 13.8 volts to appropriate fuel pump terminals. Works only when isolated source of voltage is applied = Good pump motor;
2. Test wiring leading to the pump whith those wires disconnected. Wires energized with 13.8 volts =/- a few volts = Good connection to battery.
3. Test #2 above with ignition off; wires still energized = bad connection at ignition, at relay, at auxiliiary connection point or bypassed fues block. Someone maybe has wired pump directly to battery source?
4. If #3 shows live wire, trace up the wire to find point where voltage goes away; you may end up going all the way back to battery, in which case you have a direct connection error.
5. If #3 shows live wire and you reach a relay, selonoid, fuse pad, or other connetion point, suspect that the device in line is either bad or stuck; if fuse pad, iinspect for shorted connection underneath the pad which bypass designed connections.
6. Does ignition switch check out OK with VOM? You may have a bridged connection inside of switch which coincidentally makes the fuel pump connection;
7. When all else fails, you can do as I did with my Jag XK120 -- wire a direct toggle switch to the fuel pump and dril a hole under the dash. Flip the switch on when yu want to start, flip the switch off when you turn off. Certainly solved the Smiths and Lucas problems.
HTH,
Dave
2. Short cicuit in actual fuel pump motor
3. Second relay was bad (assuming first was bad also)
4. Pump motor receiving voltage from other than wired source (hot wire, ground loop, wierd hookup, gremlin).
Here what I would do:
1. Test fuel pump with all vehicle connections disconnected; apply 13.8 volts to appropriate fuel pump terminals. Works only when isolated source of voltage is applied = Good pump motor;
2. Test wiring leading to the pump whith those wires disconnected. Wires energized with 13.8 volts =/- a few volts = Good connection to battery.
3. Test #2 above with ignition off; wires still energized = bad connection at ignition, at relay, at auxiliiary connection point or bypassed fues block. Someone maybe has wired pump directly to battery source?
4. If #3 shows live wire, trace up the wire to find point where voltage goes away; you may end up going all the way back to battery, in which case you have a direct connection error.
5. If #3 shows live wire and you reach a relay, selonoid, fuse pad, or other connetion point, suspect that the device in line is either bad or stuck; if fuse pad, iinspect for shorted connection underneath the pad which bypass designed connections.
6. Does ignition switch check out OK with VOM? You may have a bridged connection inside of switch which coincidentally makes the fuel pump connection;
7. When all else fails, you can do as I did with my Jag XK120 -- wire a direct toggle switch to the fuel pump and dril a hole under the dash. Flip the switch on when yu want to start, flip the switch off when you turn off. Certainly solved the Smiths and Lucas problems.
HTH,
Dave
