wont start
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Senior User
Joined: Sep 2008
Posts: 217
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From: marinette wi
wont start
hello all. I have a 98 150 w/4.6 I bought a year ago ran fine then. it as been sitting since, now i want to sell it. it wont start i dont hear the fuel pump run it will start on eather. i tryed to to see if i have power at the pump with a test light i dont have any. not sure if i can test it i also checked the fuses , reset , and move relay around. could use some help I would like to confirm its the pump.
thank you tom
thank you tom
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
My feeling is the gas got stale and froze the pump.
Gas is formulated with a number of chemicals.
The ligher ones evaporate and leave the heavier elements that form a gum.
Any water sinks to the bottom and causes corrosion.
What's left does not burn to well.
Get the old gas out and fill with a gallon or two with fresh gas and some 'small' amount alky water absorbent.
Cycle the ignition on and off trying to force the pump to run.
Keep checking the fuse in case it blows and be sure the relay operates.
If your lucky the fresh gas/alky will clean the pump up enough to run.
All there is from here is good luck on the attempt or replace the pump..
Gas is formulated with a number of chemicals.
The ligher ones evaporate and leave the heavier elements that form a gum.
Any water sinks to the bottom and causes corrosion.
What's left does not burn to well.
Get the old gas out and fill with a gallon or two with fresh gas and some 'small' amount alky water absorbent.
Cycle the ignition on and off trying to force the pump to run.
Keep checking the fuse in case it blows and be sure the relay operates.
If your lucky the fresh gas/alky will clean the pump up enough to run.
All there is from here is good luck on the attempt or replace the pump..
Thread Starter
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Senior User
Joined: Sep 2008
Posts: 217
Likes: 0
From: marinette wi
ok i am not getting power to the pump. i unplugged it above the tank no power i ran a power temporary wire back there and then the pump runs i dont have a book to tell me which fuse or relay location checked them yesterday with test light all were good. does someone know fuse and relay location for the fuel pump on a 98 f150? what else should i be looking for?
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Be sure you understand there will be no power there under just key on.
When the key goes to run the PCM puts out a ground to the relay to run the pump only for a second or so.
It will not restart the pump until the engine cranks over.
Be sure your not trying to find power when it's not supposed to be there.
Give the crash sensor button a push to be sure it's not tripped.
And check power when you first operate the key to run.
Go to the MOTORCRAFT WEBSITE for owner's manuel.
Download first printing for your year.
Should be fuse 19 and positon 4 for the relay.
Good luck.
When the key goes to run the PCM puts out a ground to the relay to run the pump only for a second or so.
It will not restart the pump until the engine cranks over.
Be sure your not trying to find power when it's not supposed to be there.
Give the crash sensor button a push to be sure it's not tripped.
And check power when you first operate the key to run.
Go to the MOTORCRAFT WEBSITE for owner's manuel.
Download first printing for your year.
Should be fuse 19 and positon 4 for the relay.
Good luck.
Thread Starter
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Senior User
Joined: Sep 2008
Posts: 217
Likes: 0
From: marinette wi
had the key on tryed turning on and off many times to. so i go to town and buy a manual looked it over and was going check power at the relay, i turned key on to check it out as manual says and i hear the pump run turn key to start and runs like new. i am thinking i have bad connection somewhere. i dont care as long as it works so i can sell it
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