Re: In-the-tank fuel pumps cause death and destruction

Actually, yes, yes I would! I could use the royalty payments on my patent... :-)

Oh, come on, I'm sure you can! :-)

Matt

Reply to
Matt Whiting
Loading thread data ...

formatting link
uel_pump/

I replied to another part of the thread already but will repeat here that the car my wife owns (2001 Impala) has an access door under the rear seat. Pull the seat and then unbolt the access door/cover and you can then remove the pump.

Reply to
Eugene

Yes, and if you don't use the drain fairly often, it will be so corroded by the time you need it that it will likely just snap off anyway causing a situation more dangerous than not having it to start with. Someone earlier mentioned the comparison to airplane fuel drains. This is a completely bogus analogy for at least two reasons:

  1. The airplane drains are used before EVERY flight (or at least should be). This keeps them in good working order, at last until the seals get back and they start to seep, but then you replace the seals.
  2. Airplanes aren't exposed to the road salt and other nasty stuff that the underside of a car sees.

Matt

Reply to
Matt Whiting

Actually, their isn't. Water doesn't mix with either.

Matt

Reply to
Matt Whiting

If your fuel pump is working why would you would you drain it that way? It is very time consuming. You will not pull 72 liters or 19 gallons in a half hour.

Reply to
Thomas Moats

Yup, works great with a truck. Now do that on a mini-van. Try that on a LHS.........

Reply to
Thomas Moats

I believe the original poster said transfer pump, not the car's fuel pump. That method would work just fine.

Matt

Reply to
Matt Whiting

Are you sure? Let's do a little math. A quick Google on "electric fuel pump" gph shows us automotive pumps with volume flowrates of from 43 to

220 gph on the first page alone. Take the lowest-rated one (43 gph). Half of 43 gallons per 60 minutes is 21.5 gallons per 30 minutes.
Reply to
Daniel J. Stern

I'd have no qualms being that engineer, and here's why: Gasoline is combustible in only a narrow ratio range with air. Bored suburban kids used to get empty paint cans from the hardware store, put a barbecue sparker with long leads in the side of the can, use an eyedropper to put two drops of gasoline in the can, hammer on the lid, stretch the sparker leads and hit the button to cause a loud noise and a flying can lid.

One drop of gasoline didn't work. Three or more didn't work. TWO drops -- and only two drops -- worked.

The ratio of fuel to air is always much too high (or, if you prefer, the ratio of air to fuel is always much too low) for these hallucinatory panoramas of firy death some people (even engineers, amazingly enough) have been talking about in this thread. That's why they don't happen.

DS

Reply to
Daniel J. Stern

Well, I suppose this means that you haven't heard about enough of them then. Even with dropping fuel tanks, most of them are not nearly as hard as you might think. You are comparing replacing an electric fuel pump that is "outside" the fuel tank to replacing one that is inside the fuel tank. I was thinking more along the lines of the older mechanical fuel pumps that were attached to the engine. These were far more common on domestic vehicles then inline external electric fuel pumps.

Many late model vehicles also have access panels in the trunk that make changing an electric fuel pump a 15 minute job. Most vehicles that I work on (GM), you can have the fuel tank out in 10 minutes.

Ian

Reply to
shiden_kai

Yes he was referring to a transfer pump. Even with a transfer pump, he will not remove 19 gallons or 72 liters in a half an hour. The lines are too small in diameter. There is restriction from both the pump in the tank and fuel filter. Then once the return line is no longer under fluid the possibility of sucking air if the regulator is of an open center design. Which means you can no longer pump fluid.

Reply to
Thomas Moats

A lot. What else is there (in modern business thinking)?

Having worked in the industry for 7 years, I believe that the primary driver for designs is intial cost to the mfgr., whether in the form of parts cost or assembly labor. *IF* it can be determined that making repairs easier and cheaper will help the mfgr.'s bottom line (i.e., if the buying public becomes painfully aware of the extra cost of ownership due to a poor design), then that may influence the design. In MBA-think, if it hurts the customer or costs the customer money, but the customer never recognizes that to the point of affecting buying decisions, then there is no value added in making the design better. No matter how it's sugar coated, in reality, the term "value-added" means "it improves our profits". IOW, if it is an improvement (for the consumer), but doesn't ultimately help the bottom line, then it isn't "value added" (in MBA-think).

Possibly if it is considered to be a high rate of warranty repair item, then that might be factored in too. But I believe in this case, the prime motivator was total initial cost to the mfgr. IMO...

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Reply to
Bill Putney

The average automotive OEM not a aftermarket high flow pump is 19 to 30 GPH ( Gallons per hour ) not the advertised GPH of the high performance pumps on the first page of your google search. Pumps as a rule do not deliver the maximum advertised GPH when plumed in. There are a lot of reasons for this. One of the biggest is the size and lengths of the lines the pump must push the fluid through. The same holds true for the supply side of the pump. The amount of restriction in the filter must also be considered. You will never see the pumps rated flow, especially through the very small opening of the Schrader valve. But for argument sake the highest average for OEM is 30 GPH, is a max of 15 gallons in 30 minutes, if there is no restriction involved, but we know there is.

I routinely fill 2 and 5 gallon fuel cans for my home power equipment via the fuel pressure Schrader valve. It takes roughly 7 minutes to fill the 2 gallon can. So 3.5 minutes ( for one gallon ) x 19 gallons is 66.5 minutes. The pump is new, well less than a year old. I can shave a about a half a minute if I remove the Schrader valve core. 3 x 19 = 57 minutes.

Reply to
Thomas Moats

I thought I could find a flow table with a quick search, but no luck yet. I think you'll find that even a 1/4" tube will flow a lot more gasoline that you might guess. 19 gallons in 30 minutes is only 0.63 GPM, and that is really a very low flow rate given any pressure at all.

Matt

Reply to
Matt Whiting

Your correct, water does not mix in either. Diesel does not evaporate like gasoline which is the physical difference I was referring, and the fuel systems are not required by law to have an closed evaporative system like gasoline tanks have. Because of this most if not all diesel tanks are exposed to large amounts of outside atmosphere which contains water which condenses in the tank.

Reply to
Thomas Moats

I had to go to a Ford Exporer assy. plant one time when we shipped bad fuel pump product that made it all the way into the assembly line. The Ford guy who was dropping the tanks and swapping out the bad pumps with the Explorers up on a lift was smoking a cigarette the whole time. Gasoline was all over the floor, and the old sender units, dripping with gasoline, were being stacked into cardboard boxes that quickly became totally saturated in fuel to the side of the lift. I was simultaneously shocked and amazed.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Reply to
Bill Putney

Maybe if it's the sending unit that is not working?? Or maybe the tank itself that needs replaced??

I'm not always in a hurry to do a job. If it works out, sometimes I'll start draining the tank on one vehicle while I'm finishing up another job. It does cut into my bullshit time but I make more money.

Denny

Reply to
Denny

Are you suggesting buying a 3rd pump so that you can drain the tank to eventually install the 2nd pump???

Reply to
Al Smith

Hey hey hey! One question at a time! 8^)

Actually, the commutation (brushes) are in the fuel that is flowing thru the pump. The motor armature, magnets, pumping elements, and commutator are in the same compartment swimmimg/spinning in the fuel.

Nope. The "bearings" in the ones I worked with (supplied to GM and Ford) were simply holes molded into the plastic end caps of the motors - again - in fuel. That is typical of the modern automotive fuel pump. One reason fuel pumps can become noisy is that those plastic bushings wear (actually, usually the metal shafts wear a lot faster than the plastic due to abrassive glass fibers in the plastic) and the armature starts rattling around.

No - but there are brushes.

Magnetic drives are a great way of eliminating rotating seals, but that magnetic drive wouldn't transmit the torque needed to develop 60-90 psi. 8^)

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Reply to
Bill Putney

Sometimes that has a lot to do with the type of pump. For example, the roller vane type pump is inherently noisy. Often it would be the design of chioce for technical reasons, but the vehicle manufacturer will go with a different type for that reason alone. GM uses roller vanes but very sparingly because of noise.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Reply to
Bill Putney

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.