I have a 99 F 150 4.6 V8 with a little over 100,000 miles. The problem is that seems to crank for 3 or 4 seconds before the engine starts. Sometimes it will start right up other times it will take a while. The battery is fine Fuel filter is pretty new. Plugs have been changed but that was about 8 yrs and 40,000 miles ago. The vehicle never dies once started. I changed the Fuel pump relay just to see if that would help and it stayed the same. I thought maybe a fuel pump, but it doesn't cut out like it is overheating. Crank position sensor Maybe. Any Ideas?
Diagnose crank but hard start condition
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Turn the key to on for about 3 seconds.then off then on and then start.see if that improves it
check fuel pressure i could be losing prime
I would also suspect weak fuel pump.
YES, fuel pumps CAN BE intermittent/partial, and are not always 'all or nothing' when they are going/gone, as I have also found out recently.
An injector could be leaking down the fuel pressure overnight. Try a good injector cleaner first.
Originally Posted By: nwjones18
I would also suspect weak fuel pump.
It's not always a matter of a weak or failing pump. Sometimes the check valve fails in them- the pump runs fine and makes spec pressure, but won't hold it when not running. My old Neon did this for about 100,000 miles, before the car was totaled.
I would also suspect weak fuel pump.
It's not always a matter of a weak or failing pump. Sometimes the check valve fails in them- the pump runs fine and makes spec pressure, but won't hold it when not running. My old Neon did this for about 100,000 miles, before the car was totaled.
I tried Injector Cleaner with no change as well as the turning the key on before starting no difference. After running errands and shutting it off and restarting it there is usually the hard start. How much diagnostic work will a shop charge for this and how much to replace a pump completely?
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