Hard starting 85 F150 5.0 EFI

Asked by Jan 17, 2017 at 10:46 AM about the 1985 Ford F-150 STD Standard Cab SB

Question type: Maintenance & Repair

Seems I am having same
problem as a lot of F150 folks.
Key on pumps up 2.seconds.
turns over but no start. Been
running perfect and has been
firing right off within a couple
of seconds. But colder weather
now sometimes 6 or more
tries before it tries to kick over
and then once it fires it runs
perfectly. Hard starts only after
sitting more than a couple of
hours. Mornings the worst. I
am thinking it is the high
pressure pump. When I got the
truck it had been sitting for 9
years so I replaced front tank
and inner pump etc. Fires right
up. So from what I am reading
from other folks I need to
check the pcm and the crank
sensor? What else? I did
remove the back tank and all
the garbage involved with the
dual tank system. I am running
fuel filters to make
connections where hosed
wouldn't reach like in place of
the fuel selector valve etc.
They are a few months old
now and the tank is a year old.
It runs perfect after it starts so
I figure they are all OK. I think it
is loosing it's pressure some
how.??

4 Answers

76,235

Well on the fuel pressure it should be around 30 lbs. The fuel regulator could cause low fuel pressure also. This sounds like its electrical, not totally sure. So also check the distributor cap, rotor, spark plug wires, and spark plugs. Probably should check the spark, it should be white in color, not orange. That would indicate a weak coil.

2 of 2 people found this helpful.
85,595

How cold is your weather? If you have a bunch of fuel filters in the system maybe they are causing a fuel pressure drop.

1 of 1 people found this helpful.

We replaced the rotor and cap, plugs and new wires and still hard starting. I am thinking its the high pressure fuel pump. I did see where someone said it could be the fuel pressure regulator?? where is that located?? Its dropping only to about the high 20's but mostly staying around 30's - 50's. I am going to have to buy a gauge to see how much fuel pressure we have. Thanks, Lou

76,235

Yes check the fuel pressure, the fuel regulator is up somewhere on the motor, not sure the exact location, but just follow the fuel line from the throttle body back, you'll find a device that is round. 20° to 50° isn't bad for winter time. Where I live, I look forward to the twenties deg.

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