A different arrangement for fuel pumps

As faithful readers of my posts know, I'm changing the fuel pump on my

2001 3.0L Ford Ranger. I currently have the gas tank removed, and the pump replaced in its assembly, but I don't yet have the pump assembly back in the tank. It began to rain here in Kansas City, so I couldn't really proceed. It's dark now too.

But I was wondering: Since the in-the-tank placement makes this pump a chore to replace, isn't another design possible? What about sending pressurized air into the tank, and at the bottom of the tank have a pick-up tube for the fuel. The fuel (forced out the tube by the air) could then be additionally pressurized by outside-the-tank pumps. Wouldn't this two-stage process work?

Also, in the existing in-tank placement, since running out of gas hurts the pumps by depriving the pump of coolant (the fuel), why not have a cut-off switch that works by the float? There is a float on a leaver in the pump assembly, but it doesn't look like it does anything electrical for the pump. I think it's the fuel level sensor for the instrument panel gauge. A fail-safe circuit could be designed to work with this sensor. When the level gets too low, the pump could turn off.

-- (||) Nehmo (||)

Reply to
Nehmo
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an ingenious person can do anything.The auto makers sell more parts and service by making things (harder)more cost efficient old john

Hello, Nehmo! You wrote on 22 Apr 2006 22:04:37 -0700:

N> But I was wondering: Since the in-the-tank placement makes this pump a N> chore to replace, isn't another design possible? What about sending N> pressurized air into the tank, and at the bottom of the tank have a N> pick-up tube for the fuel. The fuel (forced out the tube by the air) N> could then be additionally pressurized by outside-the-tank pumps. N> Wouldn't this two-stage process work?

N> Also, in the existing in-tank placement, since running out of gas hurts N> the pumps by depriving the pump of coolant (the fuel), why not have a N> cut-off switch that works by the float? There is a float on a leaver in N> the pump assembly, but it doesn't look like it does anything electrical N> for the pump. I think it's the fuel level sensor for the instrument N> panel gauge. A fail-safe circuit could be designed to work with this N> sensor. When the level gets too low, the pump could turn off.

With best regards, snipped-for-privacy@comcast.net. E-mail: snipped-for-privacy@comcast.net

Reply to
<ajeeperman

OK. First, you're not supposed to constantly run the vehicle low on fuel. Do you just fill to 1/4 tank at a time? If not, overheating of the pump is not an issue. As far as your two stage design, it would add unnecessary complexity and parts to the fuel system. As for the complexity of replacing the pump in your Ranger. Did it ever cross your mind to remove the 6-8 bolts in the bed (along with 4 screws for the filler neck and one electrical connector for the rear lamps), then slide the bed back, and do the pump right there in front of you (with lots of room to lay tools, fasteners, your beverage, and even your lunch if it's that time of day)? Think the project through sir!! It's 3 hours IF you break for lunch.

Reply to
Tom Adkins

I guess he was to busy re-designing his fuel system :-)

By pulling the bed it's a 3 hour job if you break for lunch AND do your lunch nap :-))

Reply to
JohanB

Your point is??

What's hard about 8 easily acessible bolts, 4 simple screws and one electrical plug?

Reply to
Tom Adkins

Tom Adkins -

Nehmo - We've had the truck for less than a year, and naturally I don't know the fueling practices of the previous owners. But yes, there's several occasions we've ran it to less than a quarter of a tank, and I did run out of gas recently. But I don't think our fueling practices are that unusual.

Some people have told me that running out of gas could have been what killed the pump, and that Rangers are vulnerable in that respect. If they indeed are, then there should be a cut-off. It would be a simple mechanism to add.

Tom Adkins -

Nehmo - Well, yes, I did think of that, but I never did the job before, so out of caution I went with Chilton's advice, which was the remove-the-tank route. Have you done it by taking off the bed?

-- (||) Nehmo (||)

Reply to
Nehmo

Yes, I always pull the bed to do a fuel pump on a Ranger or F-Series truck. The first thing you should do is use the Chilton manual to start your next bonfire. It will serve a much better purpose. Then get the OEM ford manuals for the truck. Yes, even the Ford manual states to remove bed to R&R the fuel pump. But think about the task at hand!! How hard is it to unsecure the bed and slide it back?? as opposed to removimg the tank shield, straps and tank? A manual is no replacement for rational thinking. You are working on a truck (or car), not doing brain surgury.

As far as your fuel pump, running it dry a couple of times will not guarantee a failed pump, nor are Ford Rangers more suceptible to pump failures. Ford used the same pump across their vehicle lines. Over the years there were design changes that made certain pumps more failure prone but they crossed model lines and were not model (Ranger)specific. The pump is cooled, by design of the fuel system, by the fuel flowing through it. Once the fuel stops flowing though the pump the engine stops running, thus so does the fuel pump. The amount of fuel outside of the pump has minimal bearing on pump life.

Reply to
Tom Adkins

  1. Two fail items instead of one

- Ford's mid 80's system used the two-pump method

  1. Pressurized air into the tank.

- Interesting concept... Can we say "Stoichometric?" Heh Cant even type it... suffice to say, get your such-equipped vehicle under cover in event of lightning storms... and pray your Fuel level sending line doesnt short out.

Reply to
Backyard Mechanic

Faithful readers of your posts???? A bit presumptuous on your part to think you have an audience of the faithful.

Why not just replace the original pump with another factory unit. Did the pump really die on a 5 year old car?

Sounds like a good idea. Just run a hose to the drivers seat and blow on it periodically.

If you are worried about that issue why not try the simple 100% effective solution - keep the gas tank over 1/4 full.

Sounds like a project for someone with a lot of time on his hands.

Reply to
John S.

Which would reduce the effective capacity of the tank... wooden it!

Already a fail-safe built in, the engine stops.. and since it's not turning, the FP timer times out and fuel pump stops as well.

Ingenious, no?

Here we go again... While it may help to not leave the pump body exposed most of the time, look closely at the pump construction. It's cooled by the fuel it pumps, not the fuel surrounding it.

IOW... dont run it empty. Dont run the pump for any length of time without engine running/fuel flowing.

Reply to
Backyard Mechanic

Yes. It also solves the tank venting issues. The problem is that the failure modes in case of a tank leak or an accident are a lot worse than with an unpressurized tank.

My argument against this is that it's another attempt to use more electrical and mechanical stuff, which is prone to failure just because of the nature of electrical and mechanical things, to solve a problem caused by careless operators. I think that's usually a bad thing.

--scott

Reply to
Scott Dorsey

Dont see why not... isnt that how our legislation in various governing bodies works?

Oh.... that's right, it IS how it works... never mind.

Reply to
Backyard Mechanic

In our last episode, we saw our hero, Nehmo, laying in the sodden Kansas mud, various bits and pieces of his fuel system gathered about him..... The saga continues...

As the sky darkened and the gentle breeze gained passion, our hero's dog, Toto, moved closer...... after whizzing on the left rear tire.... suddenly, Nehmos world turned topsy turvy.....

As he regained equilibrium, our hero said "Oh, Wow, Toto.... we ain't in Kansas anymore..... I got the munchies....". And the two combined talents to design a fuel system that Rube Golberg would be jealous of..... after nehmo whizzed on the left rear tire....

Shit happens... some shit happens before we expect and other shit never happens..... In our modern world (spelled "mass production"), two seemingly identical items can be like night and day in regards to traits such as overall quality, general metallurgy, fit and finish and internal clearances.... These factors can have an effect on the life span of any component.

FWIW, my experience tells me that THE MAJOR cause of fuel pump failure is neglecting to change the fuel filter in a timely manner. If this truck has ever been run to the point where a restricted filter has given driveability issues, we can expect a premature fuel pump failure (even though we don't know how many miles or hours are on this nearly 6 year old pump).

If we have ever experienced the inconvenience of a flat tire, we don't set about designing cast iron tires.... If we have ever had a rock chip in a windshield, we don't come up with wire mesh guards....

As for introducing air into the fuel tank.... the motor on the electric pump uses a commutator and brush arrangement. As each commutator bar breaks contact with a brush, a spark occurs..... Your truck doesn't blow up because the fuel vapours in the tank are well above the UEL (upper explosive limit). If we introduce oxygen into this vapour rich environment, we can bring this mixture into the explosive range. And we are still left with the possibility of starving our newly positioned pump.

There is no real concern with allowing our fuel level to drop below 1/4 tank.... but should we allow the level to remain there? As temperature changes, so does the dew point.... condensation can settle on the inner walls of the fuel tank find it's way into the bottom of our fuel tank. Additionally, keeping the tank close to full means we have one less concern should we have the need to suddenly travel any distance... one less concern should we find ourselves in a position where we can't find a fuel source...

While I would imagine that most reading this have experienced a fuel pump failure in their lifetime, I doubt that you'll find many that have experienced multiple fuel pump failures. My last bad pump was on a car with a carburettor...

Reply to
Jim Warman

Consider posting responses under the message they pertain to.

Reply to
John S.

Come again? What are you talking about?

I'll be less cryptic than you... Since I hit reply in the thread and addressed quoted comments in the topic, how did I screw the thread up?

Waiting....

Reply to
Backyard Mechanic

My race car works this way, but it runs on methanol. I'd be hesitant to use it with gasoline because of the explosion hazard with gasoline. In a crash the fuel may spray all OVER the place.

How about using one of the older electric fuel pumps like an autopulse. That SUCKS fuel through the fuel line. You might have to take an old tank pump and remove valves and stuff, but the autopulse may suck through the in-tank pump and be mounted on firewall.

Reply to
Don Stauffer

You are way, that's WAY, over engineering this thing. Or way over thinking it at the very least.

I have an '81 Jeep CJ5 that I converted from a crappy carburetor system to multi port fuel injection. the fuel pump for the MPFI is external to the tank, and connects to the pick up that the old mechanical pump was hooked up to. The electric fuel pump sucks gas from the tank, pulls it through a filter, then pumps it to the injector rail. No need for pressurized air to get the pump going. Replacement is easy, well that's relative I suppose. All I need to do is raise the vehicle by the frame so the rear axle drops, and I can get to the fuel pump without much trouble.

I see no reason why the Ranger could not be fitted with an external fuel pump. Having said that, the internal pump has several operational advantages, and if you keep gas in the tank, it should last a very long time. The gas acts as a coolant, drawing heat away from the pump and dissipating it. The need to replace an in-tank fuel pump is often associated with running the gas to the bottom before refills. Yes, there can be other causes, but you can control the fuel level easier than you can control the other causes.

Reply to
Jeff Strickland

A simple myo-cranial in-fart-shun on my part...

Apologies!

{though I will keep my eye on you} ;)

Reply to
Backyard Mechanic

Why some [trade] magazine hasn't hired you is beyond me.

Reply to
aarcuda69062

I love it... dammit, Warman why dont you co-blog with me! would make it worth my time!

Reply to
Backyard Mechanic

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