Cleaning clogged fuel lines?

[Davidhoy]

Ran into a problem this weekend, losing power at a most inopportune moment - isn't that when all engine problems happen, right in a narrow channel with lots of traffic? Fortunately I was able to secure to boat and diagnose and resolve the problem, a clogged clogged fuel line from the primary tank to the engine. I found a glob of gunk in the 90 degree elbow between the pickup tube and the fuel line itself. After cleaning that out, I was still having issues, so just switched the engine over to use the generator's pickup tube and fuel line. I suspect that there is still some of that gunk in the lines somewhere.

I was thinking of using compressed air into one end of the fuel line, with the other end going into a container, to clear any remaining blockages. Does this sound like a reasonable method to use? Or is there a better way?

I had the tanks cleaned and the fuel polished about a month ago, so hopefully this was just some residual gunk and I won't have an ongoing problem. A lesson I learned is to always keep at least some fuel in both the primary and secondary tanks, as then I could have just flipped over to the secondary and continued on my way.

Regards,
David

[a64pilot]

I ran into the same problem, and compressed air will do the trick, try at first with a dinghy air pump, vacuum cleaner etc before you throw 100+ PSI air at it.
If this is gasoline be very careful with any kind of electric motor like a vacuum cleaner.
Use the vacuum cleaner in the blow mode on Diesel lines, never suck gas fumes into one.

[westwinds]

How soft was the material that you took out of the elbow? That should give you some idea of what it will take. Get one of those dust off cans used to blow dust out of a computer. Hopefully you can get some kind of a seal from the nozzle on the can to the fuel line.

[Davidhoy]

Originally Posted by a64pilot

I ran into the same problem, and compressed air will do the trick, try at first with a dinghy air pump, vacuum cleaner etc before you throw 100+ PSI air at it.
If this is gasoline be very careful with any kind of electric motor like a vacuum cleaner.
Use the vacuum cleaner in the blow mode on Diesel lines, never suck gas fumes into one.

Fortunately I'm dealing with diesel. I'll try the vacuum first.

[westwinds]

You may have a problem with water in the diesel promoting biological growth. The tank could be cleaned, but with water in fuel, you could get more growth and plugged filters and fuel lines. I use STA-BIL Diesel Biocide. I also use their Diesel Formula STA-BIL fuel Stabilizer once a year to keep the diesel fresh. There are other products that work. I use this brand because it is readily available in auto parts stores.

[DeepFrz]

Originally Posted by westwinds

You may have a problem with water in the diesel promoting biological growth. The tank could be cleaned, but with water in fuel, you could get more growth and plugged filters and fuel lines. I use STA-BIL Diesel Biocide. I also use their Diesel Formula STA-BIL fuel Stabilizer once a year to keep the diesel fresh. There are other products that work. I use this brand because it is readily available in auto parts stores.

+1, but I urge you to clean the tank first.

[Davidhoy]

Originally Posted by DeepFrz

+1, but I urge you to clean the tank first.

The tanks were cleaned about 5-6 weeks ago, as noted in the original post. The fuel was also polished, and treated with Biobor after it was returned to the tanks. I suspect there was already some material in the pickup tube and/or fuel lines, and it just reached critical mass, so to speak. I also had a pretty rough passage between Marathon and Fort Lauderdale a few weeks ago, which may have stirred up anything the tank cleaning missed.

The glob of gunk was about 1/2 inch long, about the diameter of the 90 degree elbow fitting to which the fuel hose is connected at the tank, and kinda gummy.

-David

[DeepFrz]

I've experienced exactly that problem at the 90 deg. elbow at the top of the tank. I urge you to check the cleanliness of the tanks unless you witnessed the cleaning. If they are clean then you are good to go.

One thing I vowed I would do, but never did, was to increase the size of the pickup and fuel line right to the filter. Something to think about.

[bierman_2001]

I'm having the exact same problem. My engine is running rough and losing power after 10 minutes of running. I've changed the filter. Removed the screen in the bottom of the pickup tube. I Took apart the elbow and fuel shut off valve to clean it out. I cannot figure out where my line blockage is located. There is no water or gunk in the bottom of my tank. It's very frustrating.

If I still have plenty of pressure at the bleed screws after the engine is shut off, does it still make sense that there is a blockage? or could there be another problem? Air? Immediately bleeding it and trying to restart it does not make the problem go away.

[Uncle Bob]

Originally Posted by Davidhoy

The tanks were cleaned about 5-6 weeks ago, as noted in the original post. The fuel was also polished, and treated with Biobor after it was returned to the tanks. I suspect there was already some material in the pickup tube and/or fuel lines, and it just reached critical mass, so to speak. I also had a pretty rough passage between Marathon and Fort Lauderdale a few weeks ago, which may have stirred up anything the tank cleaning missed.

The glob of gunk was about 1/2 inch long, about the diameter of the 90 degree elbow fitting to which the fuel hose is connected at the tank, and kinda gummy.

-David

Hi, I have experienced much the same, dark brown to black gunk in the form of small sticky "balls" that backed up at an elbow in the fuel line until the line was almost full and only allowed a very small amount of fuel through.
After realising what the problem was (I was told that it was most probably ashfeltanes) I replaced all the fuel lines with 3/8 soft annealed copper, no elbows, just radius bends and flare fittings. I have also installed a sedimenter to each fuel line as close to the tanks as practical prior to the Racor filter and have since had no more problems.
Naturally the fuel was polished and an additive used.
So far so good.

[DeepFrz]

bierman 2001; It sounds like you may have a blocked fuel tank vent line. Next time it starts to act up loosen the filler cap and see if that helps. Or, better than that, clean the vent line.

[hellosailor]

Depending on where and how you can access the runs of the fuel line, if you have a fiberglass fish tape (the cheap ones from Horror Fright will do) or some of those yard-long narrow zip ties, you can use something like tht to "fish" through the tubing and see if you can route anything out. That may dislodge things that compressed air wouldn't. A coulpe of feet of very thin Tygon hose (aquarium air pump hose) might also do the job, or even a thin braided polypropylene line.

[sailormed]

Originally Posted by bierman_2001

I'm having the exact same problem. My engine is running rough and losing power after 10 minutes of running. I've changed the filter. Removed the screen in the bottom of the pickup tube. I Took apart the elbow and fuel shut off valve to clean it out. I cannot figure out where my line blockage is located. There is no water or gunk in the bottom of my tank. It's very frustrating.

In the Raco filter head are two 90° bends. The one on the IN line was clogged in my case. Maybe look there first for the mysterious blocage in the feed line.