I'm sure this question has been asked many times, however, I've never been privy to the answer. I spent the afternoon yesterday changing out the defunct fuel pump on my GMC Denali and I began thinking (which gets me in trouble most of the time!) Why in the world would GM place an electrically operated device (which could create sparks) inside of a very explosive container (like a gas tank) What was their logic? Mechanical stuff I can understand....electrons are very mysterious to me!
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Re: Electric Fuel Pumps Inside Gas Tanks
Submersible pumps have been around for a LONG time and, when constructed properly, are well regarded from a safety standpoint. Consider the fuel tank and understand you're working with low voltage DC to start with. Now, go a step further and understand the pump is almost always submerged meaning there's no air surrouding it to produce a combustible mixture.
Last, think of the oddles of other submersible pumps sold/used every day that connect directly to potentially lethal 115/230 VAC power sources! Plus, if you think the in-tank fuel pump is dangerous, contemplate the 'folley' of building a vehicle out of flammable fiberglass, sticking 12-20 gal of gasoline on board and letting it ZOOM down a 2-lane road where oncoming traffic is separated by only a matter of a few feet, operated by pilots who've done little more than take a written exam to demonstate their proficiency to the State licensing board. Now, there's a scrarry thought! -
Re: Electric Fuel Pumps Inside Gas Tanks
Someone once told me that one of the reasons was that the surrounding tank and fuel absorb a lot of the noise from the fuel pump, and we Americans tend (at least historically) to equate low noise levels to high quality and luxury. Sounded like a plausible explanation to me. I Once had a Porsche 911 with an electric fuel pump NOT in the tank. Before the engine fired up, you could definitely hear it inside the car. Yeah, I know, what was I thinking! I love my '81 Vette much better than the Porsche. I can actually work on this car and the parts are bargain basement priced by comparison. I'd never go back.
;-)Comment
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they use the fuel to cool the pump
so running these cars out of fuel can shorten the pump lifeComment
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Re: Electric Fuel Pumps Inside Gas Tanks
I truly appreciate the responses so far but you haven't yet made me comfortable yet! You say that "most" of the time the pump is submerged. I say that most of the time I'm about to run out of gas and I can see the pump in the back of my mind just hanging there in the vapors, straining (and sparking!) to get the last drop of fuel out of my tank!
I can see the dangers with inexperienced people driving these high-tech bullets down the road as well. But I just can't see engineering the explosive hazards into the machines in the first place.
I don't see the argument that they were trying to engineer "quietness" into American cars. Why didn't they simply insulate the noise as they've done in a lot of other cases? I think it's because they were trying to increase revenue at the dealers by making it an expensive nightmare (beyond the skill range of shadetree mechanics) to change out the pump.
I'm not really paranoid....and I've never heard of an explosion caused by the internal pumps.....it's just that most things in life make sense to me....this doesn't!Comment
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Re: they use the fuel to cool the pump
I've also heard that from the dealer, as he was taking my $300 for changing the fuel pump in my '95 Tahoe for the third time. So, that sounds like a reasonable explanation as well, plus I can't disagree with the theory of "let's make things more difficult to replace for the average owner, so they bring it into the shop", although I suspect the main deciding factor in most design decisions is not the desire to drive future repair revenue, but to drive down the cost of building the vehicle in the first place.Comment
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Re: Electric Fuel Pumps Inside Gas Tanks
Didn't an explosion resulting from sparks from a fuel pump located in a fuel tank cause an airplane crash over the Atlantic a few years ago?
I agree with you - there isn't any sense to putting a fuel pump in gasoline. I live with enought dangers - I don't need any more - especially useless risks!Comment
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i think it has something to do with
such a high consentration of gas fumes it can not explode because of the absence of airComment
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Often, fuel pump failure results from...
lack of owner maintenance in changing the in-line fuel filter. On trucks, these are typically in-line with the fuel lines and you have to crawl under the chassis to reach them instead of popping the hood. Keep the filter clean and the pump won't work so hard with the benefit being a longer pump life...Comment
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Re: Electric Fuel Pumps Inside Gas Tanks
Brad,
Aircraft have the same setup in the fuel tanks....only one incident(supposively) attributed to sparks from an unsubmerged pump...and many don't believe it was the cause.Comment
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Re: Electric Fuel Pumps Inside Gas Tanks
Brad,
Of the (how many) millions of cars built, have you ever heard of a Chevrolet car, truck or Corvette exploding from a fuel pump in the tank spark?
I recently saw a pump removed from a late 90's Chevrolet pickup. The truck would intermitantly stall, then run again. The wiring plug on the pump had gotten hot enough to melt the plastic but the tank didn't explode. It was probably caused by constantly running the tank very low before refueling. The fuel is a coolant for the pumps. The pump is sealed so no sparks are open to fuel vapor when fuel level is low.
I suspect there are other more fruitful things to worry about.
VerleComment
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Re: Electric Fuel Pumps Inside Gas Tanks
There are somewhere between 800 million and a billion cars and trucks out there worldwide with in-tank electric fuel pumps, and not one has been known to cause an explosion or fire. Standard design practice since the first ones in 1970. Not to worryComment
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Re: they use the fuel to cool the pump
So can a bad fuel pump relay! Or a bad connection at the wiring harness (anywhere inline to the pump, but usually at the pump connection) Check the voltage to the pump and the voltage at the battery while the engine is running - they should be within 1/2 volt. If the voltage drops more than 1/2 volt find out why! In my situation the relay was the culprit - but was not diagnosed until the third pump, and then only because I started fussing about three pumps in 2 years.Comment
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