Do fuel tank dip tubes get crackes?

[Larry B]

   I just finished installing engine. Let bus run for at least half hour on high idle checking for leaks. none found. I had to boost start engine so I decide to drive to battery place to load test batteries. I am now proud owner of two new sealed 8D's. On return to shop bus starts to loose power. By time I get to shop , fuel pressure is reading 2psi. Assuming I am get air in suction, I start pressure testing lines. I pressure tested line from tank to primary filter at 40psi. I valved both end and it was still holding after two hours when went home tonight. This line is 1/2" copper tube from tank to rear bulkhead, then hose to filter. Tomorrow I will disconnect at fuel pump and test filter and remaining hose. NOW I NEED HELP. How much pressure can I put on filter "o" ring seal before it blows? I removed the fuel sending unit in tank and looked inside with mirror and flashlight. It looks as if the nut holding the dip tube to the fitting inside the tank is coming loose. There are a lot of treads showing on the fitting. If this is my air source, how do I fix??If I drill this out, how serious are the fillings that will end up in tank?? Will the fuel filler take care of them? Will they even pick up with fuel? How close too bottom does a dip tube go?  My tank is about 1/2 full. My thought is to lasso the old dip tube then drill from outside and get ride of old tube.  This is where I would get filling in tank. Once old tube is gone install new from outside. Do dip tubes sometimes come loose??? All suggestions greatfully received.. 
     LarryB 
       

[DMoedave]

did you add any valves or lines when redoing you engine? I had a heck of a time running down a intermitant ir leak this past winter. It was a shutoff valve leaking thru the stem. You dident have this tank issue before did you? Good luck.

[Stormcloud]

Any chance you got some crud into the fuel line that was trapped by the fuel filters?  I would replace the filters and restart the engine, go through the entire high-idle and test drive process again, before tackling the dip tube.

And, FWIW, I read in an old post about a cracked dip tube that permitted air in when fuel level dropped below it.

Good luck!

Mark

[Lin]

If you change the filters as Mark says and you still have the problem, try adding some fuel to bring the level up to where the crack might be.  If the engine runs but stops at your present level, you have located the crack.  Of course, if you did not have the problem before your engine work, it would be a pretty big coincidence for the the pickup to to crack just now.

[akroyaleagle]

You don't say what model of bus you have.

My 05 Eagle holds 147gal. It will run out of fuel with 22 gallons remaining because of the length of the pickup tube.

It will also run out of fuel for the generator at about one fourth tank to keep me from running myself out of fuel while dry camping.

The dipstick in Eagles sometimes wear a hole in the pickup tube by rubbing against the internal tank baffles. Mine had a hole and stopped running with 90 gallons of fuel remaining when I first got it. Of course I was at a construction flag lady 30 miles south of Beaver Creek, BC!

I had to tear out some of the bathroom tile and the bottom of a cabinet to fix it. I had not saved any of the original tile and could not match it. So had to replace all bathroom tile with new.

That's how we live and learn!

I always recommend that folks check the pickup tube and replace the fuel level sending unit early in the conversion process just to preclude this.

Good Luck,

[belfert]

Never plan to use the last 20 gallons of fuel.  Most buses can't pick up that last 20 gallons or so.  I found out the hard way that my bus won't pick up the last 20 gallons.  My fuel gauge sender is now calibrated so empty is with 20 gallons remaining. 

[Larry B]

 I still had fuel pressure on the gauge this morning. If I have a fuel line leak I cannot find it by pressure testing. My bus is aMCI5B with 8-71. I installed new fuel filters when I put engine back in. I am going to change outside fitting and add foot or so of tube in a loop. The line comes over the top of tank and into the fitting right away. It does seem to have tension maybe enough to cause flare not to line up with fitting. Then go for a drive again. Would any of you have reservation about drilling into an ALUMINUM tank when it still has diesel fuel in it??? My wife thinks I have lost it this time if I am considering this.
     Larry B

[DMoedave]

you could use a shop vac as you drill and use wheel bearing grease on your tap to catch the chips if you end up having to do this. For sure check your filters again for fuel level first.

[junkman42]

Use a piece of clear plastic tubing about 6 foot long or so, hook in place of tube of top of tank. Put the tube up on a ladder or whatever, suck on tube until fuel is about four feet up tube or so and clamp it off with vice grips or whatever and see if it keeps fuel head!  If fuel remains in tube all is well in tank IE pickup tube etc.  Regards John L

[Larry B]

  THANK YOU JOHN L--- I did as you suggested with tube today. Such a simple check but so effective. The fuel level held, I even tipped bus sideways as much as possible with leveling jacks looking for a crack just below fuel line. I was ready to ripe that dip tube out. Only got a couple of hours in today. Repressured line from tank to fuel pump to fifty psi. Will check pressure and look for wet spots in morning. Does diesel fuel turn dark with time? What color is the dye that is added to diesel? My fuel has turned a medium shade of brown. Or is this something else I should  be concerned about?  Once again thanks John, you saved me a lot of work.
    LarryB

[luvrbus]

If the fuel is turning brown and leaving a brown film on metal it is starting to decompose from the moisture it absorbs from the air don't toss it just use a filtering system easy to build you one with a pump clean the fuel and reuse it  

I use a cheap 110v plastic pump from HD 29 bucks and a old filter set from a old engine or you can use a cheap water filter from the same place circulate for a couple hrs it will clean up and yea and I know the pump is not UL listed for fuel lol but it works

good luck