fuel pump shuts off at the worst times
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Joined: Jun 2017
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From: clinton,la.
fuel pump shuts off at the worst times
94 ranger 98k runs good, when it runs. problem is start motor run 1/4 mile in traffic fuel pump shuts off wait 5 to 15 min. will start up again. can drive it 2 days maybe 200 miles before it does it again, sometimes 100 yards away from driveway it shuts off. sometimes starts in the yard run 30 sec. shuts off. will always restart in 3 to 15 minutes later. does not matter if truck has just made a 45mile trip home or just started to leave work and shuts off. when it shuts off I turn the key back on can not here the fuel pump running, till I wait 5 to 15 min. replaced the relays a couple of times, did not help, change fuel filter cleaned tank out. any suggestions on maybe a cause or remedy would be helpful. and thanks.
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Joined: Apr 2009
Posts: 374
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From: Roanoke, VA
To me it sounds like just a loose connection since it can happen as soon as 30 seconds from a cold start. I'd want to very carefully check the entire power and ground circuit to the pump. Maybe even temporarily bypass the inertia switch for a couple of days as a test (keeping in mind the potential consequences in an accident!).
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Joined: Apr 2016
Posts: 650
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From: Lake Worth
Its nice you think that the fuel pump cuts off and is your problem, however you only know part of the story.
What else shuts off or is disabled when the truck will not run? does it loose spark, injector reference pulse, is the fuel pump loosing power and ground when it does not run or does it have power and a ground and still does not work?
You have more basic diagnostic work before you can decide what to perform test on.
What else shuts off or is disabled when the truck will not run? does it loose spark, injector reference pulse, is the fuel pump loosing power and ground when it does not run or does it have power and a ground and still does not work?
You have more basic diagnostic work before you can decide what to perform test on.
Welcome to the forum
Engine size is always helpful?
EaOutlaw has a good point
Your ignition switch could be cutting off power, do the dash lights lose power?
CEL(check engine light) will come on if computer detects loss of fuel pump power at Inertia switch in passenger side of cab under glove box
But if the wire, power or ground, from inertia switch to gas tank has a problem no CEL
Or if fuel pump itself has the problem then no CEL
In-tank Fuel pumps often have a thermal shut off inside, basically a bi-metal spring that Opens when heated up, then closes after it cools down.
With a full tank of gas cooling for the pump is high, as fuel level drops pump is exposed and can start to heat up more.
So it can shut off without warning, and as it cools off pump will start to work again
When these shut offs occur is there a common fuel level, i.e. it only happens below 1/2 tank
Engine size is always helpful?
EaOutlaw has a good point
Your ignition switch could be cutting off power, do the dash lights lose power?
CEL(check engine light) will come on if computer detects loss of fuel pump power at Inertia switch in passenger side of cab under glove box
But if the wire, power or ground, from inertia switch to gas tank has a problem no CEL
Or if fuel pump itself has the problem then no CEL
In-tank Fuel pumps often have a thermal shut off inside, basically a bi-metal spring that Opens when heated up, then closes after it cools down.
With a full tank of gas cooling for the pump is high, as fuel level drops pump is exposed and can start to heat up more.
So it can shut off without warning, and as it cools off pump will start to work again
When these shut offs occur is there a common fuel level, i.e. it only happens below 1/2 tank
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