Question about 1985 Toyota Cressida

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No power to fuel pump with key on

Why no power to fuel pump when is on but power when turn it over

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Because the fuel pump only runs when the engine is cranking to start or when it is running. This is a safety feature.

Posted on May 08, 2014

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1 Answer

Why does the fuel pump relay don't click when i turn the key to run? and why there is no power at the fuel pump relay?


the operation of most fuel pumps is controlled by the fuel pressure regulator
when the fuel pump gets to set pressure , the pump is switched of by the ECM at the relay level
maybe nothing wrong with your system just the system working as designed
if you have pressure in the fuel manifold when you turn the ignition on then the pump will not run but will if there is a fuel leak somewhere and the pressure drops off

Oct 25, 2016 | Cars & Trucks

1 Answer

Periodic stalling after running for awhile . when the key is turned on no power to the fuel pump. After setting a few minutes key is turned back on there is power to the fuel pump and starts


The fuel pump only turns on for 2sec when key is turned on for a fuel pump prime. The fuel pump will turn back on during engine cranking. The most likely cause of stalling on this particular vehicle is a weak/bad crank sensor.

Apr 06, 2015 | 1996 Jeep Grand Cherokee

1 Answer

My car will not start it cranks but will not turn on. So far I have changed the crank sensor I also have no spark to coil packs or spark plugs Fuel pump does not turn on when I turn the key. What is the...


Begin by checking fuses. Ignition, efi, fuel pump fuses. When key turned to on, do the warning lights and gauges work? That verifies switch has power and is sending power out. With key on, the coil primary wire to coil packs should have voltage.

No spark and no gas? Fuel pump fuse good? I think I would use a test light or multimeter to check that fuel pump fuse terminal has power to it with key on. If that's good, pull connector off at fuel tank and check for a voltage signal on fuel pump wire when the engine is cranking-if good signal, fuel pump needs taken out for replacement or inspection. If no signal check that fuel pump relay has power to it. With key off, pull the relay and check that one terminal has power to it-the feed wire for the pump. If no power signal at all, check maxi fuses or fusible links for a failure.

Sep 04, 2013 | Cars & Trucks

2 Answers

What shuts off power to fuel pump when key is turned off on a 94 GMCwith 350 engine


Power is fed to the pump by a fuel pump relay. The relay is powered by a fuse but is triggered by the computer. So when you turn the key on, the computer triggers the relay, the relay closes and turns on the fuel pump. Power is cut off only when the key is shut off and the computer kills the trigger signal to the relay

Mar 08, 2013 | GMC Sierra 1500 Cars & Trucks

1 Answer

Car cranks but won't turn over after driving fine. fuel pump is getting no power to pump fuel


no power to the fuel pump?? i suspect that their is something wrong with the immobilisor ,try the spare key first before you go any further ,maybe the chip in the key ahs dropped out ?

Dec 06, 2012 | 1994 Chevrolet Cavalier

1 Answer

New fuel pump won't run


I have had bad pumps rite out of the box but dont assume its a bad pump check for power at the pump with a test lite remember the pump only has power for 10 or so seconds after key is on if vehicle dont start pump will lose power until key is turned off then you have to turn key back on best if done with 2 people

Jun 07, 2012 | 1994 Ford Econoline

1 Answer

Fuel pump relay fault Can't find relay. No power to fuel pump. Checked fuses. All good


Model? Year?

Check per owner manual to be sure inertia switch is not tripped. Remember, fuel pump only runs for 5 seconds when key is turned ON, then it shuts off if engine is not running. Pump always runs when key is in START position.
Listen for pump to run inside fuel tank for 5 seconds after key is ON.

The PCM power relay turns on the PCM and the PCM turns on the fuel pump relay, which turns on the fuel pump.

See owner manual forfuse & relay charts.

Apr 06, 2011 | Ford Expedition EL Cars & Trucks

3 Answers

Fuel pump not getting power.Replaced fuel relay and pump. computer code was reading cam position sensor. I dont believe that would cause a no power to fuel pump. It is trying to turn and it will turn with...


If it is similar to Quest, the fuel pump runs for 5 seconds when you turn the key to ON. Then, unless the engine is running, the pump shuts off. It runs when the key is in START position though. Can you hear the pump run for 5 seconds when you turn key to ON? Listen carefully for the hum of the pump in the tank.
Normally, the power relay powers up the PCM and it applies power to the fuel pump relay. Then you get power to the pump.
Also, look at owner manual for all fuses that apply to fuel pump system.

Jan 05, 2011 | 1998 Nissan Pathfinder

1 Answer

93 merc topaz feul pump wiring harness question


The engine computer turns on the fuel pump for 3 seconds when you turn the key to "ON".
If the engine does not start, the pump will not run.
When you turn the key to "Start", the fuel pump runs all the time the key is held in start.
When you turn the key on, it actiavtes the power relay, which provides power to the PCM or engine computer.
The PCM then activates the fuel pump relay, sending power to the fuel pump.
You should have one wire with 12V for 3 seconds in "run" position. This comes from the fuel pump relay to the inertia switch in the trunk and then to the fuel pump.
You should have one ground wire. black
One wire going to the fuel guage.
You may have another ground iwre ging to a diode before going to ground.

Mar 30, 2009 | 1993 Mercury Topaz

1 Answer

No fuel at fuel rail


Assuming it is fuel injected, is the fuel pump operating? Check to see if you can hear the pump when you turn the key on, usually located in or on the fuel tank, pump should run for 5 seconds or so when you turn the key on and then switch off. If you can't hear it, find the plug for the fuel pump wiring at the pump, unplug it and use a test light across the terminals to see if it is getting any power (remember that the power will only be there for 5 seconds or so after you turn the key on). If it is getting power, then the pump is dead, and if it's not then there is an electrical problem.
Also, some euro cars have a fuel pump shut off switch which activates in the event of an accident, isolating the power to the fuel pump. Check to see if your vehicle has one and reset it if necessary.
If pump is running, check fuel lines to see if damaged or crushed.

Oct 25, 2008 | 1988 Volvo 240

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