Fuel Injection System danger: Truth or Hoax?

[archielew]

Hi All,

Nabasa ko lang sa isang comment sa Yahoo! Nagcomment sya dun sa balita na Filipino Bride sa US na nasunog sa loob ng Limo. Gusto ko kasi sana iverify kung totoo yung comment nya, and I guess here is the right place, since marami ditong experts. Here is what the comment said,

"This is really very sad, I almost experience this situation in my car, Just want to share to everyone, I don't want to name the brand of my car since most of the new model cars are having the same system specially the cars with Fuel Injection system. Most of these fuel injection system cars that are having Fuel Pump motors submerged inside the fuel tank are dangerous.
How does it work:
1. The submersible pump is build with sealed type motor that works to pump the fuel from your tank then distribute to your injection system, it work simultaneously whenever you turn your key to ON position and start the ignition.
2. The sealded type submersible pump motor, are normally subjected to worn out and sometimes they are replace with alternative replacement or even sometime original parts.
3. This submersible motor pump sometimes if not properly check and maintain they cause fire due to the pump is powered by 12VDC,and when the submersible motor pump is malfunction, let say the brush inside this motor is worn out and the moror will not run or wont turn its armature, there will be heat generated from this malfuction motor and when the heat comes to extreme, this will cause explosion from your fuel tank, this is because it ignites the fuel inside your fuel tank.

This is an experience that I observed when my well conditioned car suddenly stopped, then I tried to re-start it wont start anymore, through my trouble shooting experience, I finally come to indentify the submersible motor pump that does not work but when I'm trying to remove it I felt extreme heat from this device, I then consulted a very experience electro/mechanic and he says, "Your lucky to find out the problem or else you will surely cook alive inside you car" Thanks God it din't happen... BE CAREFULL guys."

Totoo po kaya to?

[jick.cejoco]

Hi All,

Nabasa ko lang sa isang comment sa Yahoo! Nagcomment sya dun sa balita na Filipino Bride sa US na nasunog sa loob ng Limo. Gusto ko kasi sana iverify kung totoo yung comment nya, and I guess here is the right place, since marami ditong experts. Here is what the comment said,

"This is really very sad, I almost experience this situation in my car, Just want to share to everyone, I don't want to name the brand of my car since most of the new model cars are having the same system specially the cars with Fuel Injection system. Most of these fuel injection system cars that are having Fuel Pump motors submerged inside the fuel tank are dangerous.
How does it work:
1. The submersible pump is build with sealed type motor that works to pump the fuel from your tank then distribute to your injection system, it work simultaneously whenever you turn your key to ON position and start the ignition.
2. The sealded type submersible pump motor, are normally subjected to worn out and sometimes they are replace with alternative replacement or even sometime original parts.
3. This submersible motor pump sometimes if not properly check and maintain they cause fire due to the pump is powered by 12VDC,and when the submersible motor pump is malfunction, let say the brush inside this motor is worn out and the moror will not run or wont turn its armature, there will be heat generated from this malfuction motor and when the heat comes to extreme, this will cause explosion from your fuel tank, this is because it ignites the fuel inside your fuel tank.

This is an experience that I observed when my well conditioned car suddenly stopped, then I tried to re-start it wont start anymore, through my trouble shooting experience, I finally come to indentify the submersible motor pump that does not work but when I'm trying to remove it I felt extreme heat from this device, I then consulted a very experience electro/mechanic and he says, "Your lucky to find out the problem or else you will surely cook alive inside you car" Thanks God it din't happen... BE CAREFULL guys."

Totoo po kaya to?

do it right and leave it to the professionals.
the fuel pump fuse should have cut off the circuit once the current was excessive. this could be caused by too thick of fuel ( stale fuel)or from worn out bearings or pump impeller. the fuel pump does not cause ignition inside the fuel tank since there is absence of air or oxygen (remember; liquid gasoline does not burn). even if the tank ran out of fuel, the fuel strainer sock would still be soaking in gasoline preventing air from getting into the pump motor. the possible cause of the ignition could be the wire lead inside the tank connected to the positive terminal of the fuel pump

[fourtheboys96]

OT. Sumakit ata ulo sa pag-intindi nung ng comment na iyon.

Well, first I am not an engineer.
It may seem logical that gasoline (fuel) together with an electrical-mechanical device (fuel pump) is a recipe for a fire accident.
But if I am right, it is improbable to create combustion when the fuel pump is submerged because you need oxygen for the combustion process to occur.

The probability is therefore very low for this to happen. Although I don't have the exact statistics, the fact that we don;t hear problems about this kind of fuel delivery system and it is still being used today means my thoughts are right.

[niky]

The chances of your car catching fire from a fuel pump are much, much lower than the chances of it catching fire from myriad other reasons. More cars catch fire from improperly fastened oil filters than from defective fuel pumps.

-

As jick says, there are fuses in the system to prevent heat build-up. There also needs to be the right proportion of oxygen and fuel vapors in the tank to cause a fire... it's actually not that easy to set gasoline on fire inside the tank.

And, in my experience, a modern fuel pump is not that finicky or hard to replace. You buy the whole thing as an assembly and it slots right in. It's not rocket science.

[EssB]

1. Electric fuel pumps do not immediately start whenever you put the key in ON position. Fuel pump circuit-opening relay coil would only be triggered when you turn the key to Start position -- and will continually run as long the ECU gives the trigger signal to relay coil (according to crank angle sensor signal). So when your engine stalls, the fuel pump also stops even if your key is still in ON position.
2.
3. Fuel pump generated heat is actually dispersed into the fuel. Even if the DC motor windings short circuit generate sparks, it would not start fire as there is very low oxygen concentration inside the fuel tank. The electric fuel pump power source also got a fuse protection.

[jick.cejoco]

1. Electric fuel pumps do not immediately start whenever you put the key in ON position. Fuel pump circuit-opening relay coil would only be triggered when you turn the key to Start position -- and will continually run as long the ECU gives the trigger signal to relay coil (according to crank angle sensor signal). So when your engine stalls, the fuel pump also stops even if your key is still in ON position.
2.
3. Fuel pump generated heat is actually dispersed into the fuel. Even if the DC motor windings short circuit generate sparks, it would not start fire as there is very low oxygen concentration inside the fuel tank. The electric fuel pump power source also got a fuse protection.

Electric fuel pumps do not immediately start whenever you put the key in ON position

you got this all wrong sir. the fuel enable program of the pcm/ecm/ecu runs the fuel pump between two to three seconds to pressurize the fuel rail for easier start up. fuel control varies from model to model. some are pulse width modulated, some are returnless systems, some safety features like inertia switch (ford systems-cuts off fuel pump operation upon impact), some safety features prevent fuel pump operation when there is no oil pressure ( general motors systems) and some systems cut off fuel pump operation when vehicle rolls over. too many different systems but they all pre-pressurize the fuel rail before you even crank the engine

[lowslowbenz]

^
Yes, the pump activiates the instance the key is turned. Yes, some vehicle models are equipped with an inertia switch. There are some models where a sudden drop in pressure along the fuel lines, cuts off fuel pump operation.

On MB's .. once you hear the fuel pump going "bzzzzzt" before start-up, its a clear sign its going south na.

We had a dose too much of Hollywood movies .... sorry I just got to say that ..

[archielew]

Thanks sa inyo. Mabuti pala't naipost ko to dito, madami akong natututunan paunti unti.

[EssB]

Electric fuel pumps do not immediately start whenever you put the key in ON position

you got this all wrong sir. the fuel enable program of the pcm/ecm/ecu runs the fuel pump between two to three seconds to pressurize the fuel rail for easier start up. fuel control varies from model to model. some are pulse width modulated, some are returnless systems, some safety features like inertia switch (ford systems-cuts off fuel pump operation upon impact), some safety features prevent fuel pump operation when there is no oil pressure ( general motors systems) and some systems cut off fuel pump operation when vehicle rolls over. too many different systems but they all pre-pressurize the fuel rail before you even crank the engine

Umm... on most car manufacturers today, the fuel system is one of those you mentioned. Though as an example, on older Toyotas fuel pump circuit opening relay is wired the way as I have stated above.

[jick.cejoco]

Umm... on most car manufacturers today, the fuel system is one of those you mentioned. Though as an example, on older Toyotas fuel pump circuit opening relay is wired the way as I have stated above.

still wrong sir. on older toyota, they have "luft" type or "L" type fuel injection where it uses a vane or flap type airflow meter which has a mechanical switch in the airflow mete that closes if there is airflow that deflects the vane other than fully closed position. before there is sufficient airflow, the ecu, as what toyota called it before, "enables" the circuit open relay for two to three seconds to pre-pressurize the fuel rail. so, on the toyota you mentioned, the fuel pump is enabled two ways, KOEO (key on engine off) runs for 2-3 seconds and the closing of the FC (fuel pump control) terminal of the airflow meter against E1 (earth 1 or engine ground) thereby closing the circuit to the circuit open relay to close the +B to FP (fuel pump positive lead)

[shibby75]

Its a stretched limo, why put tha fuel tank far behind when there are lots of space nearer the engine? The news says that fire started at the back. Maybe theres another source of fuel, maybe in -car stove?

Plus its a converted limo, could be faulty wiring.

[EssB]

still wrong sir. on older toyota, they have "luft" type or "L" type fuel injection where it uses a vane or flap type airflow meter which has a mechanical switch in the airflow mete that closes if there is airflow that deflects the vane other than fully closed position. before there is sufficient airflow, the ecu, as what toyota called it before, "enables" the circuit open relay for two to three seconds to pre-pressurize the fuel rail. so, on the toyota you mentioned, the fuel pump is enabled two ways, KOEO (key on engine off) runs for 2-3 seconds and the closing of the FC (fuel pump control) terminal of the airflow meter against E1 (earth 1 or engine ground) thereby closing the circuit to the circuit open relay to close the +B to FP (fuel pump positive lead)

Pre-OBD-II Toyotas with MAP fuel metering do not have that pre-pressurization of the fuel rail.

[yapoy86]

still wrong sir. on older toyota, they have "luft" type or "L" type fuel injection where it uses a vane or flap type airflow meter which has a mechanical switch in the airflow mete that closes if there is airflow that deflects the vane other than fully closed position. before there is sufficient airflow, the ecu, as what toyota called it before, "enables" the circuit open relay for two to three seconds to pre-pressurize the fuel rail. so, on the toyota you mentioned, the fuel pump is enabled two ways, KOEO (key on engine off) runs for 2-3 seconds and the closing of the FC (fuel pump control) terminal of the airflow meter against E1 (earth 1 or engine ground) thereby closing the circuit to the circuit open relay to close the +B to FP (fuel pump positive lead)

even nissan vannete with carb engine uses electronic fuel pump... the fuel pump runs 2-3 secs on KOEO then turns off.. on engine start the fuel pump runs continously.. same with our EFI F6A and K10A suzuki engine

[oj88]

Its a stretched limo, why put tha fuel tank far behind when there are lots of space nearer the engine? The news says that fire started at the back. Maybe theres another source of fuel, maybe in -car stove?

Plus its a converted limo, could be faulty wiring.

I think it's due to practical reasons. Factory fuel tanks are molded to fit a specific cavity in the car, usually under/behind the rear passenger seat or generally in the vicinity of the rear axle. There are exceptions of course.

When you convert a car into a stretched limo, it is more economical to just extend the fuel pump wiring and plumbing rather than replacing it and then moving the new tank closer to the front.

Looking at the pictures of the burning limo, the fierce fire is most definitely due to gasoline as the accelerant. I would imagine that when the fire broke out and smoke started to fill the rear cabin, the passengers panicked and moved away from the rear seats (essentially away from the doors to freedom) and got stuck in the forward part of the rear cabin. That would likely explain why all of the survivors squeezed into the canopy opening dividing the front cabin and the rear to get out.

In light of this event, it might not be too far off if the US DOT starts requiring integrated fire escape doors in the forward part of the passenger cabin.

[jick.cejoco]

Pre-OBD-II Toyotas with MAP fuel metering do not have that pre-pressurization of the fuel rail.

yes with the "D" or "druck" type efi system, the circuit open relay is closed by the STA (starter signal) while cranking and taken over by the pcm FC to close another control circuit of the circuit open relay- this is for the 7AFE corolla

[jick.cejoco]

Its a stretched limo, why put tha fuel tank far behind when there are lots of space nearer the engine? The news says that fire started at the back. Maybe theres another source of fuel, maybe in -car stove?

Plus its a converted limo, could be faulty wiring.

by far, the safest place to install a fuel tank is below the floor pan in front of the rear axle. there had been other locations: jeep mb- below the driver;s seat, volkswagen- in front of the front bulkhead behind the front axle, pontiac fiero- below the floor pan between the driver;s seat and the passenger seat, the real hummer H1- similar to the pontiac fiero, mustang 64 1/2- the worst location: in the trunk above the floor separated from the passenger compartment only by the cushion of the rear seat (gotta be ford engineering), jeep wrangler- behind the rear axle in front of the rear bumperette, international harvester pickup trucks- inside the cab between the seatback and the backwall,
the newer cars have composite fuel tanks for corrosion resistance, lightweight and spark resistance in the event of a collision.
whatever happened was a freak accident or failure to do proper maintenance or bad modification of a sedan into a stretch limousine. the fuel tank is supposed to be isolated by a non combustible wall from the occupants. or maybe the fuel pump access opening below the seat had been removed and not reinstalled. had there been a leak in the fuel system, the driver would have been alerted by the MIL (malfunction indicator light) giving a diagnostic trouble code P0440- evaporative emissions control failure and if there was liquid fuel leak, the driver would have smelled it

[shelu]

fire due to faulty fuel pump inside the fuel tank is a remote possibility. it takes 3 elements to start a fire: fuel, heat and oxygen. the first 2 is present inside the tank. however, oxygen is absent inside the tank. i think there may be other sources of heat which caused the fire during that unfortunate incident in the US.