On odd thing happened on the way back from a short ride, less than 3 miles each way.

Just had my tank powder coated (EFI) and installed a new gasket and sealing screws. I also replaced the stock cap (2001) with a Kuryakyn gas cap and LED fuel & battery gauge.

With the stock 5 gallon tank, I was 168 miles into 5 gallons. On the way to the store, the bike ran great. The way back though it started sputtering and acting like it was running out of fuel. Normally I get about 200 miles on a tank but it was acting very odd.

I pulled into the gas station and started pumping. No more than 1/4 gallon of fuel and it started running out from under the spedometer, not a lot but enough to make you say "what the hell ...".

I stopped pumping and waited about 20 seconds, wondering what the hell could be happening. If the tank was empty, how could I be up to the bottom of the EFI plate already? So I wiped the gas off and pumped another gallon in the tank, this time it didn't leak.

The ride home went off without a hitch, no sputter or any indication of something wrong.

Once home, the console came off and I looked at the gasket. Sure enough, it was leaking ever so slightly from the bottom side of the EFI plate. The screws were tight but I found some blue painters tape under the gasket (just a little) from the installation. Now there wasn't a lot of tape, just a little but it was soaked with fuel and came off very easy. Needless to say, the tape is gone and the EFI plate is back on, all screws are tight and I'm still scratching my head.

Searching the forums, I found a few posts on "vapor lock" and it appears to happen when the tank is low in fuel. The Kuryakyn gas cap is vented but was on VERY tight, I could barely budge it, even with the key.

When I opened the tank to fuel up, it didn't hiss or give any indication of a vacuume. The whole thing makes no sense other than the cap, which is new and this IS the first tank full of fuel since powder coating. It does appear to seal the tank pretty well though, the outer ring has a gasket as well as the center cap that completes the closure. I'm thinking the tank was really air tight.

So, if you were a betting man (or woman), would you think vapor lock OR something else.

Thanks in advance for the help!

 

Wow I haven't seen a vapor lock since I had my 1950 mercury back in 1971. I pulled into a gas station one day bought a pack of smokes came out and the car would not start. I was fussing with it when this old timer came out and said vapor lock I looked at him like where is this guy from car would not start he went and got the water bucket poured some on the back of the motor maybe on the fuel pump he then said try it now and bang she turned right over said he had a merk and that it would happen once in a while. I know this has nothing to do with the bike but it brought back memories

 

nikonf8, I like what you did with your signature background. That must be artifically blurred? I'm a Nikon man myself

 

To powder coat, I believe they have to get the tank to bare metal to get the powder coating to "magneticaly" stick. I have heard horror stories where they have bead or sand blasted tanks then did not clean out the insides well. You do have a strainer sock in your tank, pray that it is not getting clogged with debrie, as it would easily stop you withing a few miles. I hope it is something easy like a loose pump wire.

 

I blasted the tank myself and it was sealed, nothing got into the tank. Good point though !!!

When I took off the EFI tank plate, the fuel filter looked clean and I saw no debris floating inside the tank.

It is nearly impossible to have a leak in the system as I re-used the pump and hoses. Never had a problem with this in the old tank.

I'm leaning towards the tank not venting properly but haven't found anything to support this theory.