"89 F-150 only runs when cold.
09-10-2007, 01:16 AM
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"89 F-150 only runs when cold.
"89 F-150. 4.9L. Dies, I figure it out and replace the fuel pump in the front tank, and replace fuel pump relay, runs great for a week. Starts sputtering as if running out of gas, dies. I replace the fuel filter, runs good for a couple of days, starts sputtering again, I think there is air in the lines, not sure how to bleed them but I let fuel out the shrader valve on the rail, heard air, but maybe need the special tool. And HERES THE KICKER! It runs great when cold, then gets up to operating temp. and starts dying like no fuel, and dies, wont start. Let it cool I can go a few more miles. If you guys cant get this I dont know who can. Not enough $ for a mechanic at this time. New job, trying to get there, been a great truck. Please help. Thank You... BigDbear
09-10-2007, 07:56 AM
#2
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Most of the time when an older ford won't start when hot, then will after it cools, it will be the TFI module.
Last edited by ma94xlt; 09-10-2007 at 11:13 AM.
09-10-2007, 04:56 PM
#4
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In response to how to purge - the air can be purged by cycling the ignition switch from OFF to ON several times, allowing the two-second timer on the fuel pump to push fuel on through to the relief/bypass valve on the fuel rail. You will hear some unusual 'whooshing' noises as the air is being pushed through.
It appears that you have the dual tank setup - does it do this on either tank, or one specific tank? If specific to one tank - perhaps a bad pump or tank selector switch? Seems coincidental that this problem starts after the work done.
In regards to the problem - one other thought/WAG came to mind. Any chance of vapor lock occuring?
When you heard air from the fuel rail - could you tell if it was being pulled in, or pushed out?
'Pulled in' would probably be normal, as I would think the system would be draining.
'Pushed out' may be a problem if the truck had already been started and was running normal. Not sure how air could enter a pressurized system while running, especially on an intermittent basis. If the gasoline has vaporized, and that's what's venting, we may be onto something. Have any changes been made to the fuel rail, or do you see any reason that the fuel rail or line could get overheated? Is it possible that the fuel rail bypass/relief valve back to tank is not working / stuck closed?
My money would still be on the TFI module at this point, though.
It appears that you have the dual tank setup - does it do this on either tank, or one specific tank? If specific to one tank - perhaps a bad pump or tank selector switch? Seems coincidental that this problem starts after the work done.
In regards to the problem - one other thought/WAG came to mind. Any chance of vapor lock occuring?
When you heard air from the fuel rail - could you tell if it was being pulled in, or pushed out?
'Pulled in' would probably be normal, as I would think the system would be draining.
'Pushed out' may be a problem if the truck had already been started and was running normal. Not sure how air could enter a pressurized system while running, especially on an intermittent basis. If the gasoline has vaporized, and that's what's venting, we may be onto something. Have any changes been made to the fuel rail, or do you see any reason that the fuel rail or line could get overheated? Is it possible that the fuel rail bypass/relief valve back to tank is not working / stuck closed?
My money would still be on the TFI module at this point, though.
Last edited by wde3477; 09-10-2007 at 05:03 PM. Reason: added question
09-10-2007, 10:03 PM
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What is the WAG, vapor lock was my first thought. I dont use the rear tank and havent for years. I researched the TFI module and not only does it make sense, but ford lost a class action law suit on this one. Bad design sounds like. Im going after this one. I will let you know. Thanks a million! bigDbear
