Where is the inertia switch for a 1986 Ford F-150 300 ci 4.9 liter

Asked by Steven Dec 28, 2018 at 01:35 PM about the 1986 Ford F-150 STD Standard Cab LB

Question type: Maintenance & Repair

I have a 1986 Ford F -150 300 inch straight six 4.9
liter Regular cab. I’m the second owner bought
from a 92 year old lady whom bought it new.
Always garage kept. No rust! My problem is that
truck will start up run great for 5-8 miles then dies.
I’ve already replaced everything I could think of.
Then it may start after a few minutes or, up to 1
hour or longer 24 hrs. I’m thinking that it may be
the inertia switch. But I cannot find it. Also it
seems to die after going over a bump. If anyone
has the answer please advise ! Thanks  

3 Answers
26,790

oilyspill answered 5 years ago

I looked up your fuel pump in online parts book, it showed mechanical fuel pump, there is no inertia switch. The inertia switch is for electric fuel pump not mechanical. Just my opinion. When problem is ongoing, cranks good but won't start, have a helper crank it while you check for spark at the plugs and proper fuel pressure. Could be other issues? If you have a distributor, in the past some fords have had problems with tfi module. Some people even carry a spare in their glove box. I don't know if that module is your problem?

2 people found this helpful.
Best Answer Mark helpful

Steven answered 5 years ago

Thanks for the quick response oilyspill! I’ve changed it could be a faulty one. I’m a disabled veteran who hasn’t gotten anyone to help. I have a new distributor that came with a new one. I’ve put new plugs and wires. Also a new fuel pump. I had heard about the module and I now have a new one. I’m just trying to get it fixed by myself. Thanks for the information that you looked up. That will save me a lot of time. Thanks again .Sincerely,Steven

Mark helpful

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