Fuel cut off in case of accident

Yves · Post by **Yves** » Fri Jan 18, 2008 9:38 am

Anyone know how you could accomplish a fuel cutt off of the fuel pump when the car had an accident ?

Thanks

TheMonkey · Post by **TheMonkey** » Fri Jan 18, 2008 9:51 am

ford has a product that is covered in the megamanual. i ordered one from boostengineering for $15. has not arrived yet, i reckon he was trying to pick up some more this week from pick-n-pull.

http://home.earthlink.net/~beanbooger/b ... gineering/

read through fuel supply section: http://www.megamanual.com/

rufusbooth · Post by **rufusbooth** » Fri Jan 18, 2008 10:28 am

I second TheMonkey's suggestion. These are available off most ford FI cars from late 80s to mid 90s. Cheap at any pick-n-pull or if one is not close boost engineering is an option.

Cheers,

Rufus

Vicoor · Post by **Vicoor** » Fri Jan 18, 2008 3:03 pm

I'm pretty sure I read somewhere in the megamanual or on this forum that a spare user configurable output can be used to control the fuel pump and shut it off below a predetermined RPM

But dang if I can find it now

I'm sure someone else can elaborate.

FixItAgainTony · Post by **FixItAgainTony** » Fri Jan 18, 2008 5:10 pm

I seem to remember it would shut down automatically - I could not find a reference to it, but I think I found it in the code below. If I am reading this right, the fuel pump will shut down after it loses synch / ignition events and times out.

The spare ports should do this also. I'd check to see if the port operation requires an ignition pulse before they happen. Some items, like EGO are not sampled unless there is an ignition pulse. If you have a V2.2 stim, you can test the port / fuel pump operation pretty easily. Kill the tach and see if a port based on CLT / MAP / IAT etc. still works.

The Fuel Pump shut off switch sounds like a better set up for safety as an accident could still leave an engine running. I have also heard of rollover switches for off road vehicles.

v2.33.c ~line 2520
// check rpm for stall condition (<50> (18750/inpram.no_cyl))
{
// Engine is stalled, clear all in engine
PORTE &= ~0x10; // Turn off fuel Pump
*pPTMpin[2] &= ~0x04; // Turn off fast idle ** Bug Fix By Guy Hill **
ign_reset();
}
}
// if no tach pulse within 2 sec
else if((lmms - ltch_lmms) > 15625)
{
PORTE &= ~0x10; // Turn off fuel Pump
*pPTMpin[2] &= ~0x04; // Turn off fast idle ** Bug Fix By Guy Hill **
}

Deaninkc · Post by **Deaninkc** » Sat Jan 19, 2008 8:41 am

I tried using the Ford inertial shutoff switch, since it was already in my Capri but under race conditions it sometimes cutoff the fuel pump at inappropriate times. It was mainly under high G loads in two different directions or when the car left the ground (only at Mid-Ohio) and landed hard. It does have to be manually reset. The fuel pump does shut off if there is no ignition event so I feel pretty safe.

78Spit1500Fed · Post by **78Spit1500Fed** » Tue Jan 22, 2008 2:31 pm

The code in the MegaSquirt would cover pretty much any situation where the engine died as a result of the accident.

Having been in 5+ accidents in my lifetime (none my fault) I can say from experience that this is unfortunately a rare occurrence.

In all but one, the engine continued to run (automatic transmissions) and in the one that did kill the engine, it was a manual transmission that thankfully stayed in gear. (Thankfully because the car was pointed down a hill with a rather steep drop-off at the end.)

I STRONGLY encourage the use of one of the cutoff switches mentioned in the manual. FYI, they're on all the Ford Focus variants in the passenger-side kick panel. Easy to get to... two screws and it's yours.

EDIT

I forgot to mention that these seem to be of at least two different varieties... perhaps differentiated by age? The one I installed in the Spit (for the LP electric fuel pump) has been known to trip with very minor bumps: speed bumps in the JC Penny parking lot is the best example I can think of. The one used in my old Mustang, however, never once tripped that I could identify. Even when I was T-boned by another Mustang at 10ish miles an hour. (don't ask)

-Brian

rufusbooth · Post by **rufusbooth** » Fri Jan 25, 2008 6:08 pm

I 100% agree with Brian, In my humble opinion a cutoff switch is mandatory in any situation where an electric fuel pump is involved (low or high pressure). In the 2 accidents I have been involved in the motor continued to run after impact (carbed vehicles).

Be safe, these things are a dime a dozen.

Cheers,

Rufus