Fuel tank , and lines question

5B Steve · December 16, 2011, 05:55:14 AM

While on the subject of the previous post by Lostagain, I have a question, on the fuel tank of a 4104 is there

any type of strainer, check valve, on the end of the pickup line? The reason I ask last weekend LarryP and I

had problems getting fuel to his filters. Tank is 75% full, new fuel pump. Note we added a new line (original was

sucking air) Would it be possible that one of the lines in the tank is restricted in some way?

Steve 5B......

Ed Hackenbruch · December 16, 2011, 06:20:30 AM

Although possible, ie. filters/line restrictions, i think that you have the answer when you said you replaced a line. Takes awhile to get all of the air out. Last year i was distracted while changing my fuel filters and pulled both of them at the same time instead of just pulling one and filling it and replacing it and then doing the other. As soon as i heard the line draining back to the tank i knew i had screwed up!

First and only time i lost prime in 8 years of servicing the bus. Took over 2 hours to get prime back and to do it i had to call my brother to come give me a hand as i could not get it by myself.

5B Steve · December 16, 2011, 06:57:27 AM

Ed, We have pulled the filters several times and filled them. Seems the engine will run just on the fuel in the

filters only. I haven't removed the plate on top of the tank to see if something has come loose. I saw a previous

post where there was a picture of the elbow coming from the tank to the line and their was alot of crud in the

fitting, maybe that's where the restriction might be.

Steve 5B....

luvrbus · December 16, 2011, 07:03:34 AM

Doesn't a 4104 have a washable inline screen somewhere in the system ?

thomasinnv · December 16, 2011, 08:11:18 AM

another possibility to consider, though remote, is that the dip tube might have a hole in it near the top.

Ed Hackenbruch · December 16, 2011, 02:53:27 PM

Steve, you are right. It will run for a bit on just the fuel in the filters. I also had them off and refilled a bunch of times before we got it to keep running and that was with a fuel pump pumping fuel out of a bucket into the filter housing. That fuel line is probably close to 25 ft. long from the tank to the filter and will take a long time to refill. That is why i am thinking about doing the same thing as JC, Brian, and Clifford and putting an inline pump as close to the tank as possible.

5B Steve · December 16, 2011, 05:26:29 PM

Quote from: luvrbus on December 16, 2011, 07:03:34 AM
Doesn't a 4104 have a washable inline screen somewhere in the system ?

Clifford,

Not sure on that question, maybe JR would possibly tune in on that one. Thanks!

Steve 5B.....

Len Silva · December 17, 2011, 06:52:19 AM

The original primary filter, mounted on the right firewall, was not a screen but was a cleanable strainer. I'm guessing that most have been replaced with spin-ons by now.

zubzub · December 17, 2011, 07:10:48 AM

fwiw lightly pressurize the fuel tank, crack open the fitting at the primary fuel filter ( fuel screen really) and wait til clear fuel comes out ( no bubbles) then you will know the line has no air in it.
By "lightly" I mean just a few pounds, just enough to push the air out the line, too much pressure an you will be having other problems (ruptured tank etc...).

jjrbus · December 17, 2011, 06:28:52 PM

Different circumstances, but my line was plugged with algae. Had to blow line out with compressed air. It showed up as a slimy substance (think snot) with black in it in the primary fuel filter. It was a very small amount, less than you would think would cause problems. JIm

DMoedave · December 17, 2011, 08:07:48 PM

Cant say for a 04 but our GM has a screen at the end of the pickup tube. It had cloggged with alge once.

5B Steve · December 18, 2011, 07:52:47 AM

Quote from: DMoedave on December 17, 2011, 08:07:48 PM
Cant say for a 04 but our GM has a screen at the end of the pickup tube. It had cloggged with alge once.

With that being said, would it be possible to remove the lines at the elbows and under low pressure force air

downward to remove the clog, or just remove the plate and clean the pick up tube. What we need to do is

something to get the bus back to Larry's asap.

Steve 5B......

TedsBUSted · December 18, 2011, 09:40:48 AM

I don't believe that the typical production '04 would have a strainer at the dip tube in the tank.
It probably would just have been too difficult to service. Remember, most fuel used to be a lot "dirtier" than it is today.

I'd suggest some basic systematic troubleshooting.
Since removing "the plate" for dip-tube access was mentioned, I wonder if the new suction line is correctly connected to the dip-tube fitting and not to the return fitting? If it helps, the dip-tube elbow is threaded directly into the tank's top and the return goes through the "flatiron" or "plate" where the vent and whistle lines connect.

Next up would be to vacuum and/or pressurize the suction line from the engine end, to check for leaks or blockage between there and the tank's fuel. If necessary, split the connection at tank and repeat the test to isolate the last leg of dip-tube, into the fuel. A flare plug and cap may be helpful for leak testing purposes.

Ted

DMoedave · December 18, 2011, 05:41:56 PM

we removed the plate after loosening the union at the elbow and cleaned the screen.

jjrbus · December 19, 2011, 04:38:33 AM

How bad was the screen, did it work?

Don't leave us hanging