I have a 1986 Ford FS Bronco 302 EFI....I ran great when I got it and
then I had to go out of town for a couple weeks...so it sat un-started
for about 3wks or so....Some friends and I replaced the valve cover
gaskets in my truck when I got back due to some smoking...problem fixed.
Now, I can’t keep my truck running and it’s hard to even get it started.
When I do get it started, I have to hold the gas pedal down and keep the
RPM's above 1800 to keep the truck running....when I take my foot off
the gas, it dies when it gets down to idle speed....I have changed the
fuel filter and the gas that drained out in the process didn't even
smell like gas....could this be contaminated gas?
If it ran good BEFORE you worked on it and now it runs bad AFTER you worked
on it. Then you have made your own running problem!
I know that this engine you have to REMOVE the upper plenum off the intake
to replace the valve cover gaskets.
If you didn't replace the upper plenum gasket or it ripped or slipped. Then
this problem MAY be your culprit. This will cause the symptoms that you are describing from your truck.
To see if I am correct: get the truck started and spray throttle body
cleaner around the base of the upper plenum chamber. If the engine has a
vacuum leak the engine speed will smooth out. If it does seems to respond
to the throttle body cleaner. Then look to see what is causing the vacuum leak and repair it.
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