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Best way to flush a fuel line?

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348AMX View Drop Down
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    Posted: Oct/05/2013 at 1:35am
I had removed and had my gas tank cleaned and some pin holes on the top welded up about 5 years ago and had also installed a new stainless fuel line from tank to fuel pump.

Going to install a repro stainless steel fuel sender with in tank filter soon, but before I do would like some suggestions to flush the fuel line of any sediment from moisture from storage over the past couple of years. I always kept fresh gas in though, so given that it is is relatively new and the tank was gone through I dont think it would have a ton of varnish or anything..but would like to get the line flushed of any sediment.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amxdreamer Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 1:45am
blow it from the fuel pump backwards with LOW air pressure. make sure everything is cool, no ignition sources, no trouble lights etc and something like a jerry can to catch anything that comes out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 12:19pm
Would simply shoving the nozzle extension of a supersize can of carb cleaner in the end and emptying the can be good enough, given that it flushes it out the end into a container?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Freecat1 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 4:38pm
I might suggest un do both ends from pump and tank. Plug one end and fill with Seafoam let sit over night and then flush with fresh gas. Just spraying in cleaner might not clean the whole line.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 6:10pm
today I simply filled the bowls of the carb and stuck the pump to carb supply line into a clear gallon container without a filter.

I put some dry gas and techron fuel system cleaner in the gas tank and started the engine. It filled the gallon container up pretty quick and I shut it off.   The fuel is very clean; I didnt see anything floating around and no sign of water. I put that gas in a lawn mower and did some yard work, ran fine LOL.

There isnt much fuel in the gas tank left; it's under 1/4 but not on empty, and whats in there is a mix of gas probably a year old and fresh gas I added recently. I guess the stuff in the carb fuel bowls I saw was isolated to the carb since the fuel comming throuh the line and tank is clean, and now I have some piece of mind. I was afraid of seeing lots of that black ash looking crap that was in the carb filling that gallon container, but it is nice and clear!

I think I'll just let that techron and dry gas sit overnite and then just run the gas tank empty this way with the fuel transfering to the clear container since this is also flushing the fuel pump. I want it to competley empty so I know what that gas on the bottom of the tank looks like....but not seeing anything dirty yet to warrant dropping the fuel tank or replacing the sending unit.

Edited by 348AMX - Oct/05/2013 at 6:19pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 7:21pm
I would totally replace the line. < 100 bucks, you'll never get it all clear

Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 9:36pm
I could replace the line but, it's a larger diameter than stock stainless steel repro that I installed in 2007 so it's "relatively new" and I dont think the stuff that was in the carb is in the line or the tank. So I don't think it needed a "cleaning" but a flush instead to be sure there was'nt anything in suspension in the fuel.

I'm starting to think what I saw in the carb bowls was deterioration of the paper element from the in line fram fuel filter installed between the fuel pump and the carb. I guess if when I flushed the line I saw sediment comming out and then it ran clear I'd be wondering what was still there, but it came out clear from the get go, so there is nothing in the line that was in the carb.

We'll see after another gallon or 2 of this procedure if that changes and anything unclean starts comming out, if it just keeps comming out clear I think the flush served its purpose and is conclusive enough and I'll get a new/better filter.

Edited by 348AMX - Oct/05/2013 at 9:49pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6768rogues Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2013 at 11:20pm
I use brake cleaner. Spray a good amount in the line and blow it through with compressed air. Then I do it from the other end. Brake cleaner removed gunk well and does not leave residue.
Why Ramblers? Chicks dig 'em. Whatever it is, I can take it apart.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SONOFAMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2013 at 4:13pm
I just bought Easrwoods aerosol injected cleaner and aerosol injected lubricant. These come in a kit for like $25 bucks shipped and have long tipped adapters for the lines. I will try this tomorrow after I drop the tank on my 71 AMX.
I got a newer clean tank off of eBay that I'm gonna use. My car was sitting for 20 yrs so I don't know what's in there. I put a new piston in the 401 and she ran great for a couple weeks but now it's backfiring thro the carb and hesitating real bad.

I am hoping this will solve the issue.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2013 at 9:41pm
Flushed out about 3 more gallons and the needle is on/dropping below E now, so there must be 2 gallons max in the tank I would think. The fuel was still very clear no water, but I did notice a few very tiny "floaties" swimming around at the bottom of the container. So it looks like there is probably some sediment at the bottom of the gas tank since the previous 2 gallons didnt show any.   I'm sure the fuel line itself is good to go for the same reason. they are very tiny and really hard to see in the container, so I'm guessing the fuel sock in the tank is getting iffy or may have come off.

Think I'll drop the tank and rinse it out real good and install the new stainless steel sender/filter assembly and may put the correct vacuum fuel pump on in the spring.
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