Dirty Fuel? Best way to clean?
 

Hi

On my F650Gs twin - having just arrived in Sudan - at Wadi Halfa - I think I have dirt in My fuel system - loss of power - sounds like only one cylinder firing most of the time etc - I suspect some gunk was stirred up when the tank ran dry yesterday.

What is the best way to sort this - a fuel additive? Or do I need to take out the sparks and clean them? Or the injectors..?

Any suggestions welcome!

Guy

Running dry wouldn't make any difference. Any dirt in the fuel will sink to the bottom regardless of how much fuel is in there, and the outlet from your tank is at the bottom!

You can get tank cap "socks" which help to filter any fuel you put in, but the best protection is to keep your standard fuel filter in good condition. If you have a blocked injector now it may be worth getting a new replacement, and once you're going again see if you can get the faulty one ultrasonic cleaned.

That is a fairly "high tech" bike so even relatively simple operations might be a challenge if you don't know your way round your bike. ???

IMHO, it IS relevant that your ran tank dry. I've done this many times and seen results inside in the Carb, fuel pump or injectors, petcock and various filters. Right before you run dry your sucking up A LOT of crap of all kinds!

At this point it may not be cleared up with chemical additives, which often can help if used early on. You could also have WATER at bottom on your tank, and now WATER is in: 1. Fuel pump filter 2. fuel lines 3. Injectors

Spark Plugs will be fine. Leave them alone.

If you can I would remove fuel tank or at least remove the Petcock. Flush it out old fuel and check for debris. If you have access to your in line fuel filters, well, check them, clean if possible or replace.

Your fuel pump also should have some sort of internal filter. Some are cleanable or replaceable, some not. You can remove your fuel pump from fuel tank (it's inside of tank) Sometimes just flushing it out will help. Of course tank must be drained of fuel to do this. USE CAUTION HANDLING FUEL!

Water is easiest to remedy. A quality fuel additive can help absorb water in fuel and make it burnable.
Water, like debris, will settle to BOTTOM of your fuel tank, so running it DRY is not ideal as once water is in your injectors or fuel pump.

If you can, pre filter your fuel at fill up. I use Women's nylon stocking bits. Works great. I also run TWO in line filters plus the petcock has a filter. So, in all ... 3 filters. By far most effective is pre filtering fuel when filling up, using Nylon stocking.

Without this, this is what was lingering at bottom of my tank after just 2000 miles using suspect fuel.
https://photos.smugmug.com/photos/i-...Xfm4zRK-XL.jpg
This is only part of what was lurking at bottom of my tank and gathered round my Petcock. Lucky for me this did not affect the bike's running. But I never ran it near dry and I have an old DR650 with a Carb. So easy. Unstoppable. bier
https://photos.smugmug.com/photos/i-...8b2QH6h-X3.jpg
Above is one of my 3 inline filters ... this tiny one is the last before fuel goes into Carb. Dirty but it still worked, bike ran.

With fuel injection you may not be so lucky. Most problems happen with the Fuel pump, which can sometimes be destroyed by crap collected. And if debris gets into injectors, they may need replacing.

With luck simple flushing your fuel system best you can may do the trick.
But at some point, you should do everything mentioned above and clean it all up, replace filters and such.
Good luck! bier

Great thanks for the in-depth reply!

Yes in this situation I would rather have a carb bike of course but then again the bike has been amazingly well-behaved for an awful lot of miles. Just my luck it choses to slack off just as I arrive in Sudan!

Putting various bits of information together, I'm pretty sure that the fuel filter is clogged and that is causing the fuel pump to overheat and therefore cut-out. It only happens after a long ride and relatively high speeds.

Also I found when I removed it that the strainer that goes ahead of the pump has fallen off into the tank at some point!

I am going to try back-flushing the filter to clean it and failing that trying to find a similar-enough one in Khartoum - maybe one from a car.

The filter after the pump is usually paper .. and it swells with water .. as well as getting blocked if there is too much dirt.

Finding a similar sized filter at some car shop is probably your easiest solution. Try for fittings on both ends that match. Easiest to take it off the bike and into the shop.
I'd also get a new filter posted to you at some point further along your travels .. say 2 weeks away? Depends on if you have some where to send it? If sending to a post office then you want to be there not more than a week after it arrives, and not less than the time it arrives.

In the mean time ... keep the fuel level up. The pump is working hard against the resistance of the filter - meaning it gets hot. And that heats the fuel .. the fuel cools by the area it contacts the fuel tank .. so the less fuel the less cooling and the hotter the fuel gets. As the fuel is heated by the pump as it goes through the pump .. if the fuel gets too hot it boils and goes to gas state .. and that causes misfire!

If it does pay up .. stop and let it cool. If you have spare water then dribble it over the fuel tank.

you can easily take all filters our and see.

I have now cleaned out the fuel tank (plenty of dirt in there!) and cleaned and reattached the strainer. I have also back-flushed the filter (on my bike it does not include a regulator in fact) - a lot of dirt came out of it - so I am hoping this will keep me going for a while and in Khartoum I have a biker friend who says he can find me equivalent pumps and filters so I will at least ride on with spares and relatively cheaply.

The bike seems to be running smoothly so far anyway.

Thanks all again for all your help!