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Fuel Inertia Switch


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Had a pretty strange experience today!.... with the Esprit, before anyone asks :P

In summary, engine died while driving, seemed (lack of) fuel related. Managed to coast to a fuel station. Thing is, the fuel guage still showed 1/4 full, and the fuel warning light wasn't on :(

Tried to restart a number of times, no joy. After thinking about the problem for a while, I decided to try resetting the inertia switch (pushed the little rubber thing on the top, don't know if anything happened!). As I'd only just done the firewall bolts, I thought it was quite possible that I'd banged the inertia switch with a wrench while tightening the bolts. Anyway, still couldn't start the car, so I pushed it to the petrol pump, and filled it up.

Next turn of the key, it started perfectly! So, question now is, what was the problem?

Could it be that, even after reseting the inertia switch, it still required a couple of tries before the engine would start?

Or, was it really out of fuel, in which case why did it show 1/4 tank with no warning light?

Hmm, I'm a little puzzled! :):D

If I tripped the inertia switch while doing the firewall bolts (most likely answer, I think), how far is it possible to drive before the engine finally gets starved of fuel?

Any thoughts on this?

Rob S
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1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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I've fallen foul of this twice. The last time it happenend after changing the fuel filter, i had been checking a few things and turning it over each time. After pressing the switch the car did take a second or two before it fired.

However, you shouldnt have been able to start the car after fixing the bulk head bolts if the fuel inertia switch had been tripped by this action, should you ? :D

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I had the same problem a while back, the engine died while driving. After changing the fuelpump relay all went well except a week later the same happened again and could not be started anymore. Phoned home to bring me some tools for instant repair. The inertia switch was the problem, so i took off the electrical connector and bypassed the switch with a paperclip which was bent in shape and put in the connector. Drove the car home and ordered a new inertia swith (around 25 euro). After mounting the new switch the car is running fine again. Opened up the old switch and found nothing really wrong with the switch except for dirty contacts.

The old switch was never set (reset pin coming out, push to reset) so it was not suspicious the first few times.

A few things to check,

* is there a signal coming from the ECU to the fuel pumprelay when you turn the ignition key (remove cover from relay and use a multimeter or look at the opened up relay)

* Is fuel pump running when you manually activate the fuelpump relay ?

* Check Fuse if OK clean contacts.

Hope this helps


Edited by fjmuurling

Esprit Freak

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