Petrol substitute for leak testing

[Via]

Need to work out where I've got fuel leak on ER5, put a Jerry can of fuel in 2 weeks ago and tank is now dry.

Can anyone recommend anything to use instead of petrol to put in tank to diagnose leak? Think it's getting into carb so don't want to use water and flamability of petrol aside it's too expensive to put in tank if it's going to all leak out

Got a UV dye I normally use on cars for leak testing so was going to plonk that in mixed with whatever and leave for a day as no noticeable leaks.

[megawatt]

Do not start engine!!!! Drain oil from sump and check for fuel.

My fuel valve passed fuel through the carbs, into the airbox, then into the engine. I fixed it by fitting two separate valves. One for main, one for reserve.

You may be lucky and sort it by cleaning the fuel tank valve, replacing the diaphragm and cleaning the carb float valves. ER5s do this a lot.

[Via]

Starting no issue as no fuel left

When I bought it was told it recently had new fuel tap and to be fair was only shiny bit on bike so tend to believe that.

Is there diaphragm in tank or is it just tap? As know taking tank off according to manual you just pull lines off with tap in on or res, but if I do that tank just empties. Looking at diagram for fuel tank though I can't see anything that would stop tank emptying anyway.

Do think float valve needs to be looked at though as accidentally left tap on PRI when rebuilt it while I got distracted and next minute had fuel running down swing arm, but set to on or res was fine.

[megawatt]

Starting is an issue as you probably have fuel in your sump.

[Via]

Meant no worry of me starting it

[fastbob]

ER5s do this a lot.

 

They most certainly do ! I don't think you need to mess around with fuel substitutes , the missing fuel has either soaked into the ground or has filled the crank case. My ER5 did this and there are numerous reports of this happening on the ER5 forum. I suggest that you check the fuel tap diaphragm and replace if necessary.the main culprit will be the carb float valve needles . Even if they are new , the tiniest fragment of dirt lurking behind them will cause flooding . The best way to fix this for certain is to remove the carbs and take out the floats and needles then blow out the debris by applying an air line to the valve seats while covering the opposite one .

[fastbob]

Starting no issue as no fuel left

Do think float valve needs to be looked at though as accidentally left tap on PRI when rebuilt it while I got distracted and next minute had fuel running down swing arm, but set to on or res was fine.

 

This is essentially the answer to your own question , see my main post.

[Via]

Finally got time to take a look...

Just took fuel tap off and seems ok, visually diaphragm looks good and new still (did say he had it replaced not looking before I got it) I can't blow through fuel line with it on and in reserve it blows back through main line if I cover that again can't blow through it.

Need to take carbs off anyway as probably have a sticky float needle (hence it flooding out when I forgot to take it off prime) but no wiser where my fuel has gone.

Not drained oil yet though airbox looked dry (but has had no fuel for a while now)

[megawatt]

My fuel tap was exactly the same. Couldn't find a problem with it, but it still did it. Fuel into sump via a leaking float valve and the airbox.

[Via]

Ok well back in the warm for now, back being crap today so only a half arsed effort

Next weekend will strip carbs off and attack the float needle.

Did you replace your tap anyway to be sure or left it?

Did it need replacement needle or just a clean and refit?

[megawatt]

I said earlier, I fitted two taps and two tee pieces for main and reserve. Strip and clean the carbs and check and clean the float valve needles AND SEATS.

[fastbob]

There is an alternative way to stop fuel getting into the sump via the air box . Pop out the air filter and shine a torch inside and it will become clear what the problem is . There is a step inside the air box that means that any fuel will go straight down the crankcase breather instead of out of the other drain in the rear left corner. The fix is simple , extend the crankcase breather a few inches up inside the air box and job done . You'll have to find a suitable bit of tube from the scrap bin . This won't cure the source of the problem but it will save buying new oil when it happens. Talking of which, it happened to me yesterday, my bike starts spluttering and dying a hundred yards up the road so I went back and sorted it out . Before I take the carbs of I always try this first . Make sure the long drain tubes are on the float bowls , undo the drain screws and let both bowls completely empty. They should both stop flowing eventually, if not then the tap is knackered . Then while still open , switch to Prime and let more fuel flow through to wash out the debris . Close the tap to Run or Res , close the drain screws, set tap to Prime and as the bowls fill up again repeatedly whack the carbs with a rubber mallet . Works for me most of the time . Have another look in the air box to see what's going on. Good luck.