jrsavoie
Recruit
Drilling or running loose is for when you have the issue and don't immediately have a replacement.
Too much vacuum has happened many times.
Even to the point of sucking the tank in
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6.5 cutting out up hills while towing
- Thread starter AMCTruck
- Start date
Too much vacuum has happened many times.
Even to the point of sucking the tank in
Big T
Well-Known Member
As Will L. pointed out, the more obvious places to start include: (1) does the lift pump work, (2) if so, how well is it working; (3) is there air in the fuel (see clear return line for confirmation).
Given the age of these trucks, I have had two now that needed new o-rings at the fuel sender because they were sucking in air. Doubt fuel tank cap has anything to do with his issue.
Given the age of these trucks, I have had two now that needed new o-rings at the fuel sender because they were sucking in air. Doubt fuel tank cap has anything to do with his issue.
jrsavoie
Recruit
The fuel cap test is incredibly easy. Just leave the cap loose and see if anything changes.
A fuel pressure gauge should be added anyway. You still should verify the lift pump is operating correctly with a fuel pressure gauge.
If the IP is being overworked, running with the cap loose will eliminate the suction in the tank and might let the IP suck fuel easier. Camouflaging the real issue of fuel delivery.
I've had and seen quite a few bad fuel cap issues. Possibly bio diesel related.
Bio tends to gum things up more than straight diesel and I was running B11 since the 1990"s
Big T
Well-Known Member
I was thinking the same: undo or loosen the cap, as opposed to drilling it.
jrsavoie
Recruit
I used to drill them to use while I waited for a new cap. After awhile I ordered - I think it was 4 - still have one left.
dbrannon79
I'm getting there!
if you ever have to drill one out, just drill into the inside part, not all the way through the top. the seam holding the top to the bottom half is never air tight where the top of the cap will act as a rain cap keeping water out if it's out in the open.
thinking of a vented cap where there is a one way check valve inside only allowing it to breath in but not out is some concern for me. mainly because this is the way my aux tank is in the bed of my truck. in the summer time with it out in the sun, I have several times pulled the cap to add fuel. if I am not holding grip on the cap there is enough pressure in the tank to blow the cap out of my hand along with seeing the tank go from a slightly swollen state back to normal when I remove the cap! This kind if think happening to a factory truck tank which has much thinner metal walls or the newer ones made of plastic make a huge concern for the tank coming apart at the seams due to the pressure, or even enough pressure that any hose in the fuel system using a hose clamp (supply or even return) could pop off and you would never know it until your loosing fuel rapidly!
thinking of a vented cap where there is a one way check valve inside only allowing it to breath in but not out is some concern for me. mainly because this is the way my aux tank is in the bed of my truck. in the summer time with it out in the sun, I have several times pulled the cap to add fuel. if I am not holding grip on the cap there is enough pressure in the tank to blow the cap out of my hand along with seeing the tank go from a slightly swollen state back to normal when I remove the cap! This kind if think happening to a factory truck tank which has much thinner metal walls or the newer ones made of plastic make a huge concern for the tank coming apart at the seams due to the pressure, or even enough pressure that any hose in the fuel system using a hose clamp (supply or even return) could pop off and you would never know it until your loosing fuel rapidly!
Will L.
Well-Known Member
This is pertaining to the fuel cap bit- which we should see if a MODERATOR can chop out all this into its own thread leaving a simple “check your fuel cap” comment and the link to this rabbit hole?
There is good and bad to the design. Hmmwv/hummers also use a plastic tank. They have fully sealed caps. But the tank has a basic breather with a vent hose hooked up to it. The vent hose just runs to a higher position- and since we have vent hoses for the differentials, geared hubs, transmission and transfer case that all run together and vent up to air filter- they ran the fuel tank vent next to that hose. The tank vent just has a little filter on the end that looks like a fuel filter a lawn mower or motorcycle would use.
Since the hmmwv doesn’t have to comply with emissions standards, they are not bound to having equipment damaging components such as fully sealed tanks.
I would never imply anyone hurt the spotted tree whales by allowing a fuel tank to vent to the atmosphere and allow those evil fuel vapors to damage the ozone layer contributing to man made global warming.
There is of course some draw backs to vented tanks besides that.
Fuel that sits a long time and is vented - the fumes you smell are actually the lighter portions evaporating away. Think of fuel like light and when seen through a prism you see the rainbow separated. All together they make the natural light we see and use.
The different colors of the fuel is basically layers of oils that given enough time undisturbed would theoretically separate heavy sinks to bottom light goes to top.
The lighter stuff we all use daily is basically the same stuff- just different weights of it:
Propane
Gasoline
Kerosene
Diesel
Engine oil
Asphalt
Asphalt out gasses and degrades over time, but not as fast as engine oil. And there is very little vapor involved with asphalt. Spill some gasoline and it evaporates quickly. Compared. And if you store it in an open container, there is so much of the light weight stuff in there that if you store 1/2 gallons in an open coffee can for a month- then try pouring it into your empty lawn mower- probably wont even make the engine run. That gasoline has made it half way down the chart to kerosene.
Now, because most of our diesel fuel now has the stupid corn juice in it- we know it can’t be stored the way diesel used to be. If I find a steel barrel sealed with diesel fuel in it from 1940- I am gonna run that fuel in a 6.5 and rejoice for both the free fuel and the better lubricity of it. And it will run perfectly. If I find same barrel age that had the bung seal off- I would pump it out trying to leave the dirt that got in and settled to the bottom of the barrel, leaving the last 1/2” inside to avoid the dirt that got in there. Then I would run it. If I was worried about have 100% power instead of the maybe 90% it has now- I would add a splash (maybe a gallon) of gasoline into it to add back the lighter hydrocarbons that evaporated away.
If you knew is was exactly 55 gallons when stored, measure how much is there now and you would know how much to add. It wouldn’t be perfect but would be so close that 99.999% or people couldn’t feel the difference even if they knew to watch for it.
Because the lighter stuff is what evaporates, and almost everything in gasoline would evaporate in that time. The “varnish or Shellack” that is left behind when gasoline evaporates and you had to clean that carburetor to get the lawn mower running again-
When you clean it with the gas, the gasoline is simply reabsorbing it. If you were cleaning it in a super freezer with propane- it would clean much easier because the fuel you are cleaning with is much lighter on that scale. Thats why when you clean with gasoline is faster than diesel. Now if you are cleaning really heavy sludge the diesel starts out breaking it down faster than gas because the two are closer together so it begins absorbing it sooner, But it won’t clean it as well once the sludge is saturated with diesel.
So any of us with grey hair learned- start with diesel, switch to gas. Problem is you finish with skin cancer & why we say to you younger guys not to do it.
Why all that? Well, the diesel fumes an openly vented fuel tank that has a gasoline filter on it to keep out dirt- seems like the perfect solution. But knowing that it is polluting your air has some legitimacy to stopping the action of it because what is easier cancsr to get- something you almost never touch unless you try or something you breathe on accident because you walk by in the parking lot.
So moral and mechanical compass says it’s ok to vent or Wanna drill it out… How fast does that tank of diesel fuel loose some of it’s pep?
2 - 12 months depending how much corn juice is in your diesel. If you live where there is none and you have real diesel but ULSD- you get 1-2 years. Basically try it and if you notice it is sluggish and you don’t want to run the 20 gallon tank weak- give it a pint or so of gasoline and hit some big bumps to purposefully mix it up.
There is good and bad to the design. Hmmwv/hummers also use a plastic tank. They have fully sealed caps. But the tank has a basic breather with a vent hose hooked up to it. The vent hose just runs to a higher position- and since we have vent hoses for the differentials, geared hubs, transmission and transfer case that all run together and vent up to air filter- they ran the fuel tank vent next to that hose. The tank vent just has a little filter on the end that looks like a fuel filter a lawn mower or motorcycle would use.
Since the hmmwv doesn’t have to comply with emissions standards, they are not bound to having equipment damaging components such as fully sealed tanks.
I would never imply anyone hurt the spotted tree whales by allowing a fuel tank to vent to the atmosphere and allow those evil fuel vapors to damage the ozone layer contributing to man made global warming.
There is of course some draw backs to vented tanks besides that.
Fuel that sits a long time and is vented - the fumes you smell are actually the lighter portions evaporating away. Think of fuel like light and when seen through a prism you see the rainbow separated. All together they make the natural light we see and use.
The different colors of the fuel is basically layers of oils that given enough time undisturbed would theoretically separate heavy sinks to bottom light goes to top.
The lighter stuff we all use daily is basically the same stuff- just different weights of it:
Propane
Gasoline
Kerosene
Diesel
Engine oil
Asphalt
Asphalt out gasses and degrades over time, but not as fast as engine oil. And there is very little vapor involved with asphalt. Spill some gasoline and it evaporates quickly. Compared. And if you store it in an open container, there is so much of the light weight stuff in there that if you store 1/2 gallons in an open coffee can for a month- then try pouring it into your empty lawn mower- probably wont even make the engine run. That gasoline has made it half way down the chart to kerosene.
Now, because most of our diesel fuel now has the stupid corn juice in it- we know it can’t be stored the way diesel used to be. If I find a steel barrel sealed with diesel fuel in it from 1940- I am gonna run that fuel in a 6.5 and rejoice for both the free fuel and the better lubricity of it. And it will run perfectly. If I find same barrel age that had the bung seal off- I would pump it out trying to leave the dirt that got in and settled to the bottom of the barrel, leaving the last 1/2” inside to avoid the dirt that got in there. Then I would run it. If I was worried about have 100% power instead of the maybe 90% it has now- I would add a splash (maybe a gallon) of gasoline into it to add back the lighter hydrocarbons that evaporated away.
If you knew is was exactly 55 gallons when stored, measure how much is there now and you would know how much to add. It wouldn’t be perfect but would be so close that 99.999% or people couldn’t feel the difference even if they knew to watch for it.
Because the lighter stuff is what evaporates, and almost everything in gasoline would evaporate in that time. The “varnish or Shellack” that is left behind when gasoline evaporates and you had to clean that carburetor to get the lawn mower running again-
When you clean it with the gas, the gasoline is simply reabsorbing it. If you were cleaning it in a super freezer with propane- it would clean much easier because the fuel you are cleaning with is much lighter on that scale. Thats why when you clean with gasoline is faster than diesel. Now if you are cleaning really heavy sludge the diesel starts out breaking it down faster than gas because the two are closer together so it begins absorbing it sooner, But it won’t clean it as well once the sludge is saturated with diesel.
So any of us with grey hair learned- start with diesel, switch to gas. Problem is you finish with skin cancer & why we say to you younger guys not to do it.
Why all that? Well, the diesel fumes an openly vented fuel tank that has a gasoline filter on it to keep out dirt- seems like the perfect solution. But knowing that it is polluting your air has some legitimacy to stopping the action of it because what is easier cancsr to get- something you almost never touch unless you try or something you breathe on accident because you walk by in the parking lot.
So moral and mechanical compass says it’s ok to vent or Wanna drill it out… How fast does that tank of diesel fuel loose some of it’s pep?
2 - 12 months depending how much corn juice is in your diesel. If you live where there is none and you have real diesel but ULSD- you get 1-2 years. Basically try it and if you notice it is sluggish and you don’t want to run the 20 gallon tank weak- give it a pint or so of gasoline and hit some big bumps to purposefully mix it up.