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Unread 12-03-2003, 10:38 PM   #1
JBFried67
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Emergency Fuel Shutoff???

Does anyone know if a 98 Wrangler had an emergency fuel shutoff? I had an accident with the Jeep tonight and I hit a light pole on the passenger side, right where the tub meets the quarter panel. I get electrical power and I can crank the engine, but it will not start, thus I was wondering if there is an emergency fuel shutoff safety or something.

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Unread 12-04-2003, 07:31 AM   #2
wrangler2002
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Quote:
Originally Posted by JBFried67
Does anyone know if a 98 Wrangler had an emergency fuel shutoff? I had an accident with the Jeep tonight and I hit a light pole on the passenger side, right where the tub meets the quarter panel. I get electrical power and I can crank the engine, but it will not start, thus I was wondering if there is an emergency fuel shutoff safety or something.
I can't say for a fact but I would doubt it.
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Unread 12-04-2003, 09:05 AM   #3
happyjeep
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Yes. I posted over "there" also.

ASD relay in the power distribution center.
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Unread 12-04-2003, 04:23 PM   #4
rkutzner
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I think it is a federal requirement to vehicle manufacturers to have an inertia cutoff switch and has been around for at least 10 years. If you are in an accident that bursts a feul line, the last thing you want is your feul pump to keep on cranking out the gas!

What I don't know is how can the relay be reset? Might be good for everyone to know.......
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Unread 12-04-2003, 04:31 PM   #5
chris06
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Quote:
Originally Posted by JBFried67
Does anyone know if a 98 Wrangler had an emergency fuel shutoff? I had an accident with the Jeep tonight and I hit a light pole on the passenger side, right where the tub meets the quarter panel. I get electrical power and I can crank the engine, but it will not start, thus I was wondering if there is an emergency fuel shutoff safety or something.
Yes, there is an auto fuel shutoff. the same thing happened to me in an accident.
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Unread 12-04-2003, 07:54 PM   #6
DouginTN
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Quote:
Originally Posted by rkutzner
I think it is a federal requirement to vehicle manufacturers to have an inertia cutoff switch and has been around for at least 10 years. If you are in an accident that bursts a feul line, the last thing you want is your feul pump to keep on cranking out the gas!

What I don't know is how can the relay be reset? Might be good for everyone to know.......
No Federal law on an inertia fuel shut off, but it can be used. Ford and other manufacturers used an inertia shut off located in the trunk. Pain in the ***, hit a big bump and bingo, the engine dies.
As computers systems on vehicles gained in intelligences, the auto manufacturers started using the PCM to control fuel flow, without inertia switches. The PCM monitors the engine speed and if it drops below a specific RPM value, the PCM will shut off the fuel supply.
Therefore, if you have a fuel line rupture, the pump will continue to pump until the engine starves for fuel and engine RPMs drop, at that point the PCM shuts down the fuel pump relay, thus, shutting off the fuel pump. Usually when starting a vehicle, the PCM will energize the relay, pressurizing the fuel system, then shut if off after a one or two seconds, until it sees engine RPM above a specified point, then it energizes the relay to allow the engine to run.
With an in-tank fuel pump, if you should roll over, the fuel would not be at the bottom of the tank where the fuel pickup tube is located; therefore, no fuel would be pumped, even if the PCM did not shut off the fuel system.

Now, if Jeep still utilizes an archaic device such as an inertia switch, it is not due to Federal law, it is due to the manufacturer not wanted to spend money in updating their PCM calibrations and functions.
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Unread 12-05-2003, 03:59 AM   #7
rkutzner
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Hey, thanks for the update. Now I'm just that much smarter. I bet that the Feds/Insurance companies pressured the automakers into having 'SOMETHING' to cut off the feul in an accident. There are safety regs they have to meet (like that dang drivers side airbag) for certain type vehicles and I'd highly doubt there isn't something out there that says "feul has to be shut off in an accident".

But, hey, I've been wrong before.............actually quite often
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Unread 12-05-2003, 07:40 AM   #8
DouginTN
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Quote:
Originally Posted by rkutzner
Hey, thanks for the update. Now I'm just that much smarter. I bet that the Feds/Insurance companies pressured the automakers into having 'SOMETHING' to cut off the feul in an accident. There are safety regs they have to meet (like that dang drivers side airbag) for certain type vehicles and I'd highly doubt there isn't something out there that says "feul has to be shut off in an accident".

But, hey, I've been wrong before.............actually quite often
You are correct, there is a Federal regulation to shut off fuel in an accident, just no regulation stating it has to be an inertia switch.

Federal/Canadian Motor Vehicle Safety Standard (F/CMVSS) No. 301This regulation covers everything from a car to a school bus, with different specifications. For a vehicle under GVWR of 4 536 kg (10,000 pounds), in a frontal collision, it cannot exceed 28 g from impact until motion of the vehicle has ceased and shall not exceed a total of 142 g in the 5-minute period following cessation of motion. For the subsequent 25-minute period, fuel spillage during any 1-minute interval shall not exceed 28 g.

For a rollover, fuel spillage in any rollover test, from the onset of rotational motion, shall not exceed a total of 142 g for the first 5 minutes of testing at each successive 90 increment. For the remaining test period, at each increment of 90, fuel spillage during any 1-minute interval shall not exceed 28 g.

The PCM controls meet these Federal requirements.
Another point is, the PCM must energize the relay to allow fuel flow; therefore, if the PCM is destroyed in an accident, the relay will open since the PCM acts as a ground switch to energize the relay.

The problem with inertia switches is in order to meet F/CMVSS, they were too sensitive. I had a few Thunderbird Turbo Coupes back in the 80s, and I lived in MI at the time. With the terrible roads (large chuckholes), quite often the inertia switch would pop and kill the vehicle, after hitting one of these canyons. Therefore, I cannot believe a Jeep, which is designed to run on roads that make even MI roads look good, would have an inertia switch.
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Unread 12-05-2003, 12:09 PM   #9
rkutzner
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Yeah, that makes sense, didn't realize we were in bed with the Canadians on auto regs.

Did 'g' mean gallons? That seems like enough to empty any tank. Or is that 'grams' or something? So maybe the ASD relay stated earlier isthe relay controlled by the PCM.........
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Unread 12-05-2003, 07:53 PM   #10
DouginTN
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Yea, it's like a bunk bed. NHTSA on top, and their regulations fall down to the bottom bunk. The Canadian government accepts most of all the specs issued by the US. One big difference is the use of daytime running lamps. It has been a law in Canada for some time, but never made into a law in the US. Some companies do voluntarily add DRL to their vehicles.
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