Fuel Pump Timer? Pump Location?

Here's my opinions:

Fuel pump timing... not sure what you mean by this. If your talking about the time the fuel pump engages when you turn the key... with the engine not running... then the answer is the computer is handling that.

I think the main reason for having the pump in the tank... cost.

As for different pumps for basically the same vehicle. The only reason I could think of is that car manufacturers are always making revisions to parts... attempting to improve them. The different pump in this case may be an improved version of a previous pump. Remeber that the improved version may or may not be backward compatible with previous versions due to mounting bolts...etc. This is one of the major reasons that application data is so vast at auto stores.

My answer is the same... when the engine is not running... the computer is the device that runs the pump for a given time limit.

www.telstar-electr> "timer" not "timing". Actually I asked in a previous thread

The pump need engine input to the computer that says the engine is running, pump away. Otherwise it times out.

Turn your key from off to run and you will hear the pump start up. It then will shut off. That is how long it takes the computer to time out.

As far as the rest goes, they wanted to make it very complicated and difficult to replace the fuel pumps solely with the purpose to make the mechanics that fix them money.

The old external electric and mechanical pumps were too easy for the average joe to get, get at and fix.

Total planned obsolescence at it's finest.

The new pumps are cooled by the fuel coming back the return line going into a jacket around them so they can make cheaper pumps and more complicated seeming systems to 'snow job' the average consumer some more.

The first generations of external pumps even had brushes you could replace....

Mike

Fuel pumps are normally controlled through a relay and few seconds 'cycle' . With the key on, the pump is engaged. If no engine movement (not running, sometimes no oil pressure, sometimes high engine temp) is detected, the pump is disengaged in usually 2-3 seconds. This 'timer is part of the Engine Management System (computer).

The pump in the tank may be a cost saver or not. The advantage of a submerged pump is it runs cooler and quieter with out suction leaks. Replacing the pump may be less than an advantage.

Interesting question and I have no answer, except for possible fuel types and fuel pressure requirements for different engines.

It's interesting that Ford makes this distinction between gas and alcohol fuels. It may mean that they are ahead of the pack with different fuel pump seals/impellers/designs to accommodate the emerging fuels. On the other hand why not supply all Fords with this capability as a cost saver. Any difference in pump parts cost would be more than made up in - less part numbers/ stockroom space, a single production line, certainly less logistics in production and distribution. This one is difficult to understand because Ford traditionaly spends a nickel not a dime. Or maybe someone is stringing you a line.

Yes. A circuit in the PCM pulls the fuel pump rely control circuit to ground, the PCM pulls the relay control circuit to ground if;

Fuel under pressure is less likely to vapor lock or foam.

The 126" pump uses a steel top flange, the 118" pump uses a plastic top flange, there are also differences in the plumbing. Apparently there is a marked difference in the design of the fuel tank/system between the two wheelbases.

Indeed, the flex fuel pump would need certain material upgrades if it is to survive the higher alcohol blend.

aside question,

not to interrupt the poster's original question, but I had to have a fuel pump installed on a '93 6 cyl. 3.3 chrysler t-c minivan - twice.

and, another engine same kind, same year model, has never had any fuel pump problems - why? just curious.

what can cause an electric fuel pump in the gas tank to fail?

mho v=83e

Well, thanks. That settles it.

-- (||) Nehmo (||)

The ECM (engine control Module) has circuitry that provides the ground for the fuel pump relay. That circuitry contains a timer circuit that only lets the pump run for a couple of seconds if there is no rpm signal recieved from the engine.

Less expensive to make a pump that does not need to provide lift ( suction to pull gas from the tank).

Fuel tank configuration is different on different wheel bases. Therefore pump design varies.

Different pump construction materials are needed to handle the corrosive properties of extra methanol

not to interrupt the poster's original question, but I had to have a fuel pump installed on a '93 6 cyl. 3.3 chrysler t-c minivan - twice.

and, another engine same kind, same year model, has never had any fuel pump problems - why? just curious.

what can cause an electric fuel pump in the gas tank to fail?

mho vfe

Other than contamination there is the added heat of excessive current when the pump has to work against a partially clogged fuel filter. Constant strain equals early failure.

Timer? There is no timer for the fuel pump.

It's actually cooled by the fuel surrounding it. External pumps are cooled by fuel going through, but internal pumps are cooled by fuel surrounding them. Obviously there is a certain amount of cooling by the fuel passing through, but the pump is submerged, and that's where the primary cooling is accomplished.

That's a good question. I'd guess that the tank is different on different wheelbase trucks, but that's only a guess.

Jeff Strickland -

I saw a diagram, which someone in one of these NGs posted, of a similar fuel pump. It appeared the motor was in the center of a cylinder and fuel driven by an impeller went around the motor as it went up through the cylinder. Thus the *motor* is submerged in the path of the fuel. Also, the pump I have, which is a little smaller than a toilet paper tube, comes with a rubber quarter-inch-thick sleeve to cushion the mounting clamp (maybe it quiets the pump too). If the designers expected liquid coming in contact with the exterior of the pump to collect heat, they would have at least made holes in the sleeve.

-- (||) Nehmo (||)

doesn't the fuel pump "run" according to need, like an ac thermostat, if there is "no call" for fuel, it doesn't run??

mho v=83e

No.

suction to >pull gas from the tank).

YEAH, you bet, until it comes time to replace it, then, the honeymoon is over.:--)

AND, why does a tank pump run 150-200 bucks, plus a gouge for installation, and a hang-on suck pump runs - quite a bit less?

mho v=83e

straight gas, >part is indicated by the 8th character of >the VIN - V for flex-fuel - U for only >straight gas. =3D=3D=3D AND, when a vin number has neither an "U OR "V" for the 8th character, but a "X" - what does the "X" indicate?

mho v=83e

when >the pump has to work against a partially >clogged fuel filter.

=3D=3D=3D=3D

mho v=83e

How about an example of "quite a bit less?"

=3D=3D=3D=3D you surely aren't serious?

camshaft driven pumps use to cost 10-15 dollars when they were in vogue, probably don't make them anymore, electric pumps 40-50 dollars - tank pumps today run 150-200 bucks,

but you must take into consideration that the - pumps and present day fuel systems act synergistically, new design, requiring a different configuration all together.

mho v=83e

No less serious than you are.

Let's see... Camshaft driven pump, 4-6 psi and delivers fuel in pulses Electric fuel pump, 30-65 PSI and delivers continuous steady pressure. So, to steal a phrase from a slightly shortsighted individual, "you surely aren't serious?"

You consider it in 2006, I was considering it 28+ years ago.

Yeah, EFI versus carburetors and all that mysterious stuff...