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Discussion Starter · #1 ·
My boyfriend's truck runs great most of the time but sometimes at any speed it could start sputtering and acting like it's running out of gas then we'll put the truck in neutral and shut the truck off and pull to the side and then able to crank it right back up and then it'll run strong and then it'll start sputtering again and sometimes it cuts off by itself and dies but has power and sometimest we cut it off and then we can crank it right back up. Sometimes it takes a minute for it to be able to crank back up.
 

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Discussion Starter · #3 ·
All this started after he ran out of gas one night and he was trying to make it like a hundred yards up the street to get to the gas station and he had a couple old bottles of liquor in the back of his truck that had been in a fire (long story) and he poured them into the tank trying to see if it would make it to the store and that is what started all of this
 

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Well for starters you don't want to run vehicles below a quarter tank to begin with too often it puts excessive strain on the pump. And considering it was run out of gas that also damages the pump.

And the fact that alcohol was put in the tank that doesn't help either.

Chances are the pump is now failing and you will need to have it pressure tested to verify and most likely will need a new pump.

All of that alcohol will need to be removed from the tank as well.
 

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The alcohol is not your problrm, any bottle of liquor is 40 percent alcohol and 60 percent water.
You need to get rid of the water.

You need to add alcohol to the tank, it will collect the water, mix with the gas and burn off.

Go to a paint store and get a can of wood alcohol
 

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Discussion Starter · #6 ·
The alcohol is not your problrm, any bottle of liquor is 40 percent alcohol and 60 percent water.
You need to get rid of the water.

You need to add alcohol to the tank, it will collect the water, mix with the gas and burn off.

Go to a paint store and get a can of wood alcohol


We were about to drop the tank and clean it out. How do I know it'll help though? You been threw somethng similar maybe?
 

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hell no,, do not drop the tank ! use a suck tube tool to suck out the gas .. see if the gas is looking good .. if the gasoline is looking bad then suck all the gas out then drop the tank .
now because the truck keeps the gas below 1/4 tank level the fuel pump creates a failure and the fuel pump over speeds and has air bubbles in it .. keep the gas 1/3 higher .. fill the tank to 3/4-7/8 level ..
you must use TOP TIER GASOLINE ... ALSO many put injector cleaner when you do the oil change in the gas tank.
 

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apparently running tanks low on fuel being hard on a fuel pump is a myth. the fuel being pumped through it is what keeps it cool. not it being submerged. Motor City Rick proved that and he was above a master tech, he was who the top GM engineers called upon to figure out the problems that they couldnt.

his case in point was.... external fuel pumps not being much different than internal pumps.

however I like to keep a full tank of fuel and refill it at 1/4.

Id say pouring liquor in the tank is what killed it. there was probably a domino effect. these trucks read how much ethanol is in the fuel and adjust how to burn it accordingly. I dont think the other ingredients in the booze is guna be good for it.

is there a check engine light and are there any codes?
 

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apparently running tanks low on fuel being hard on a fuel pump is a myth. the fuel being pumped through it is what keeps it cool. not it being submerged. Motor City Rick proved that and he was above a master tech, he was who the top GM engineers called upon to figure out the problems that they couldnt.

his case in point was.... external fuel pumps not being much different than internal pumps.

however I like to keep a full tank of fuel and refill it at 1/4.

Id say pouring liquor in the tank is what killed it. there was probably a domino effect. these trucks read how much ethanol is in the fuel and adjust how to burn it accordingly. I dont think the other ingredients in the booze is guna be good for it.

is there a check engine light and are there any codes?
Well I have personally seen it happen multiple times where vehicles are run low on gas and run out of gas and the pumps burn up.

Just happened last month to a neighbor actually.

I also replaced my fuel pump in my S10 and the brand new fuel pump even gives a warning not to run it below 1/4 tank otherwise it can damage the pump.

So whether it is a myth or not I am not going to test it myself after seeing it happen multiple times.
 

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tell that to Rick, he could never repeat that. not once. I wish Rick was still here.... he was above the highest accreditation a mechanic could be. saw the entire evolution of the 350 and had 50 years experience. we were lucky to have him here but we fear he has moved on.... I'll see if I can find his explanation. but think about it... theres MANY external fuel pumps.

my dad taught me to not let it fall below 1/4... I teach the same thing. BUT for different reasons.... as in not to run out of fuel.
 

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relevant info, from Rick to the OPS question....
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snip
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Another thing I'm sensing is your perceived interpretation of physical data. Concerning flex fuel, is the flex fuel sensor gives an "estimated" value of ethanol, not a precision amount. It has no capacity to measure the "actual" specific gravity of fuel going through the sensor. If the specific gravity is too light in hot weather, ... then the risk of premature ignition is present which in turn gives low power.

Ethanol is less powerful than pure gasoline itself. Here is rule about ethanol that gets people confused about: "The Differences Between Ethanol and Gasoline. A gallon of gasoline provides one-third more energy than a gallon of ethanol. Blending ethanol and gasoline at a ratio of 85 percent to 15 percent (E85), the blended fuel is nearly thirty percent less powerful than pure gasoline. Cite: The Major Differences Between Ethanol and Gasoline

Next, the PCM uses a an excel type file and gives approximate guesstimates as to spark duration / timing along with so many milliseconds of open pulse with the fuel injector. Adding up all these variables create the risk of cylinder misfire, lower power output, and misdiagnosis to driveability concerns.

Being you have a flex fuel vehicle doesn't eliminate that aspect of misfire / low power.
 

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heres one of Rick's explanations on why low fuel doesn't actually kill a pump....

Well guys, ...the fuel gauge in any GM vehicle runs from zero (empty) to 90 ohms (full). Low fuel will not activate unless it's under 10 ohms. Or in layman's terms when the gauge needle is just about empty. The gauge is not even closely accurate at fuller stages. When a tank is filled to the brim and the needle goes down to 3/4's, ...it's actually half a tank. Every fuel tank has the capacity to overfill the travel of the gas float.

Another wives tail is gasoline is needed to cool of the fuel pump. Answer, ...bull chit!!! When pumps are tested (all domestic manufactures) in an engineering lab they have zero contact with fuel on the outside jacket. They are direct fed through a series of supply and discharge hoses. T type thermocouples are used at various points on the pump itself to measure various temperatures. If and when a pump gets hot it's due to fuel restriction caused by a restricted fuel filter or fuel line. The other problem not recognized, the fuel sucked up through the center of the fuel pump is the heat sink if the pump ever got hot. It's very rare for a fuel pump to exceed 110 degrees in a low fuel situation. Maybe in Arizona.
 

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continued.... sorry it wont let me edit to insert another quote. that's pretty dumb.

Well, part of my diagnostic work was also testing / evaluating "claimed" failures. All "failed parts" went back to the lab for analysis. With a couple hundred fuel pumps that went back to the lab (from our diagnostic teams), 90% of it was using high ethanol fuels, fuel additives which melted the plastics (including pick up screen) over the long haul or restricted fuel filters (causing higher fuel pump output pressures) buy using contaminated / cheap fuel. If there was a pattern, it was made into a TSB.

As for running lower than a quarter tank (actually 1/8th tank), ...more than half the fuel pump body is exposed when the fuel gauge is reading a quarter tank. Your at half tank when your fuel gauge reads 3/4's. Fill your tank at 3/4's and see the results. This is where everybody gets dazed and confused fuel pump overheat rumors, gas mileage computations and baseless theories.

As for "ANY" certified mechanic, this needs to be cleared up. If anybody claims they are a "mechanic" they DO NOT have diagnostic capability. They are glorified parts changers buy using previous experience to make judgement calls. When a person calls themselves a "technician", they are stating they have "diagnostic capability". Know complex diagnostic procedures, along with total system functionality causes and effects. I personally test them on their diagnostics when I have to make an appearance. I ask certain everyday questions to see where I'm gonna go with the solution. If somebody told me the fuel pump failed because of overheat by running less than a quarter tank all the time, I'd ask them where was the thermocouple placed to measure temp, have them explain where the burn patterns were on the unopened fuel pump housing, or "how" they ascertained that fact without a technical evaluation??? Similar to people who cut open oil filters and make a diagnostic judgement call if they are cheap or not.

As for the claims from "According to their Auto Test Center supervisor and certified mechanic John Ibbotson" I would have to ask them did you do your fuel pump testing under TS16949 standards (global standards)??? Did you use "any" thermocouples in your test data???, ...did you ever report your test procedure / results to the public??? I read a lot of claims, ...but when comes down to the actual testing methods and evaluations, ...it's all crap without consistent "hardcore" physical data. Where is the "physical data from these two??? It should have been in their article.

Funny thing is, ...I've been running (multiple) vehicles down to fumes (1 gallon or less) since electric fuel pumps (TBI's) came out in the late 70's (pushing 40 years). "NEVER" had any type of fuel pump failure. And these pumps go 20 years or 200,000 miles. Half the battle is change the fuel filter and stay away from ethanol based fuels. Don't throw in fuel additives.
 

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Discussion Starter · #14 ·
apparently running tanks low on fuel being hard on a fuel pump is a myth. the fuel being pumped through it is what keeps it cool. not it being submerged. Motor City Rick proved that and he was above a master tech, he was who the top GM engineers called upon to figure out the problems that they couldnt.

his case in point was.... external fuel pumps not being much different than internal pumps.

however I like to keep a full tank of fuel and refill it at 1/4.

Id say pouring liquor in the tank is what killed it. there was probably a domino effect. these trucks read how much ethanol is in the fuel and adjust how to burn it accordingly. I dont think the other ingredients in the booze is guna be good for it.

is there a check engine light and are there any codes?
Well I have personally seen it happen multiple times where vehicles are run low on gas and run out of gas and the pumps burn up.

Just happened last month to a neighbor actually.

I also replaced my fuel pump in my S10 and the brand new fuel pump even gives a warning not to run it below 1/4 tank otherwise it can damage the pump.

So whether it is a myth or not I am not going to test it myself after seeing it happen multiple times.
Could be because it sucks up the trash in the bottom of the tank when it's that low clogging up the filter putting strain on the pump.
 

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nah...
this truck has an in the tank fuel filter. plus the old style has a filter screen sock that is impossible to suck anything up through that is not a fluid.
 

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Discussion Starter · #16 ·
Could be because it sucks up the trash in the bottom of the tank when it's that low clogging up the filter putting strain on the pump.
There are a lot of different scenarios and it really just depends on the circumstances of that particular vehicle. Lots of factors to take into consideration
 

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sorry I missed that your the op. are there any codes present? there should be, and they may be stored codes without an existing check engine light. get an obd2 scanner and see what codes there may be which should help point you in one direction or another. on these trucks there are many sensors and if one messed up it alters things and does not want to run right... so a code should be set....

check that out and let us know.
 
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