I need help plz

Asked by Dec 23, 2015 at 06:23 AM about the 1999 Ford F-150 Lariat 4WD Extended Cab LB

Question type: Maintenance & Repair

I have a Ford F-150 with the 4.6v8! My problem is I
bought the truck from a guy that had it sitting up for a few
years! Amazingly with a hot battery it crunk and ran (
missing terribly )! It had a check engine so I put a code
reader on it to find out #5 was missing! So common since
I started cheap plugs were first, afterwards my miss went
to #6 immediately changed wires and finally no check
engine( mind you it was running allot better than day 1)
but it still has so power it idles rough just like its missing
still, I have tried injector cleaner also a air filter but still no
change! My fuel mileage is terrible and over drive is
literally pointless because of how bad it lugs!!! I think I
have ruled out a firing problem but I am lost on this
vacuum system! Any input at all will be much appreciated!
I have also considered fuel problem but how could I check
fuel pressure or better yet how would I check a vacuum
system! If I could jus get a few tips and a starting point I
think I can handle it but as of now I'm lost!!!!!

Advice would be appreciated~|. Sincearly

A frustrated ford owner

3 Answers


If the truck was sitting for a few years, the gas will be not usable, I hope you drained it. If not, that might be one of your issues. You can check fuel pressure with a gauge, you can rent one at any local auto parts stores, check online, or Utube for demonstrations.


Siphon out all the gas in the tank. Change the fuel filter. Hopefully it is not part of the fuel pump inside the tank, as in newer F-150's. Now check the fuel pressure at the engine. Gauges can be purchases for 25 bucks. The readings can be obtained from the net as well as the testing procedure. Check resistance on your wires via multi-meter. New Fords suppose to be about 5K ohms per foot, but check for your model. Use the multi-meter to check the primary and secondary coil. The NET will show you how. Check the easy and little cost items first. Don't throw parts at it until you determine the problem.

You could have some stopped up injectors cause even if you put injector cleaner in it they can still have a ball of gummed up gas in them from sitting up, or a bad coilpack because if you have the 8 coilpack system like mine I had to replace one just about every week until I replaced them all when I first got my truck, or a stopped EGR valve which happens to my 98 all the time, and as far as the vacuum system one of the lines could have a hole in it from being dry rotted and the only way to find the hole is to crank the truck and get a can of starter fluid and spray down the lines and if you hit a hole in the line it will start clear up the rough idling but the vacuum lines and injectors are probably your best bet cause they won't throw the check engine light

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