Inertia switch issues

[Josh]

I suspect my inertia switch of failing, but has done so in a strange matter. With the plunger up or down the fuel pump operates. I know it was functioning correctly before cause i bumped it and had to troubleshoot a no-start. However I used it recently as a theft deterrent and forgot to push the plunger back down - but the car still started and ran fine. So I suspect the switch.

Just wondering if this is a common problem. i have hear of them failing open, but not closed.

[sdg3205]

I had this recently. It caused door lock issues. How are your door locks?

[nkemp]

My car would periodically die. After flatbedding it back home and resting the night it would start fine the next day. This occurred multiple times. I replaced the inertia switch and it works fine. BTW ... I used a Ford Mustang switch. It is wired to the old inertia switch which now acts like half the plug which eliminated cutting & splicing wires. As such I can use the original part number without any wiring change. But there are only so many times I'll use the original design before moving on to something more modern.

FWIW... the very early cars had a recall for the switch. If my memory serves me correctly, they replaced the original switch and installed/moved the new one onto the footwell wall.

Nick

[David T]

My car would periodically die. After flatbedding it back home and resting the night it would start fine the next day. This occurred multiple times. I replaced the inertia switch and it works fine. BTW ... I used a Ford Mustang switch. It is wired to the old inertia switch which now acts like half the plug which eliminated cutting & splicing wires. As such I can use the original part number without any wiring change. But there are only so many times I'll use the original design before moving on to something more modern.

FWIW... the very early cars had a recall for the switch. If my memory serves me correctly, they replaced the original switch and installed/moved the new one onto the footwell wall.

Nick

There was a recall on the inertia switch. If your inertia switch doesn't have a splotch of white paint on it you should replace it and if it is still on a bracket off the Lambda counter it should be moved to the side of the footwell.

[Josh]

I removed anything door lock related, just the wires are left. I will be wiring in a more modern setup later, so basically no feedback there lol.

I like that idea Nick! What year mustang is it from? might be able to snag one from the JY.

My switch is mounted on the lambda counter bracket. I could care less where its mounted, it seems fairly secure and out of the way there.

[nkemp]

I like that idea Nick! What year mustang is it from? might be able to snag one from the JY.

It was a JY find so I don't recall the year.


My switch is mounted on the lambda counter bracket. I could care less where its mounted, it seems fairly secure and out of the way there.

As I recall, the switch was more sensitive when it was mounted on the lambda bracket and would trip by bumping it and even brake or clutch movement. As such you should move it to the sidewall.

[Josh]

It was a JY find so I don't recall the year.

Fair enough. Could I trouble you to take a picture of it so I know what to look for? If not thats ok.




As I recall, the switch was more sensitive when it was mounted on the lambda bracket and would trip by bumping it and even brake or clutch movement. As such you should move it to the sidewall.

*inserts foot in mouth*
haha will do.

[nkemp]

Fair enough. Could I trouble you to take a picture of it so I know what to look for?

Google (use images) "Ford Mustang inertia switch" and you get more, more varied and better pictures than I can provide. If you want a picture of mine I'm happy to oblige, but I suspect Google will do a better job. Note that some circuits show the inertia switch controlling a relay, others it controls the pump directly. The latter provides a bit more safety from a jammed/locked/frozen/welded relay.

[Josh]

Im seeing a few different kinds. Im thinking its the second one, which is from a 86-93 (fox body)

[nkemp]

Im seeing a few different kinds. Im thinking its the second one, which is from a 86-93 (fox body)

Mine is the first one. I suspect, but cannot say for sure, that any one that will carry the current will work. When looking, a pretty good indicator that it will carry the current is to look for one with heavy wires, not thin ones.