Fuel Flow

[sidecarKev]

Had my 79F (still un-named) going last night for its first "extended run". I still wasn't able to ride it beacause I need brakes bled, the battery was sitting on the floor and the sidecar isn't quite ready to go down the road. It smoked like crazy for a minute or two. Sounded great and was really smoooooth. One problem though, I'm having trouble getting gas to the bowls. I didn't have a real good look at the situation last night but here is what I know. I have cleaned out the tank , tore the petcocks apart and cleaned those up also. Put on new full line and used fuel filters. I also routed the lines the alternate way shown in the tech tips to help reduce air in the line. When I first put the tank on all was good, started up and ran fine. Tried to start again, no deal. Noticed that fuel was not flowing like it should be, saw a little sediment in filters and line. Took the tank off and blew in the lines. Noticed that bowls could not be full otherwise I would not have been able to blow air into them. Put the tank back on and it ran again for a short time. Tried to start again, no luck. Took tank off, gas flows easily out of pertcocks. Go through the whole procedure again and bike starts. The tubes for bowl venting on a 78-79 are clear. I also have the gas cap open, to aid flow.

There are a few things I can think of. Screens before float valve are plugged again. Filters I'm using are wrong for application. Filters are already clogged. Are some filters only made to allow gas to flow one way?

I'm going to try routing the fuel line in a more direct route, see if that helps.The gas just doesn't want to flow, even on prime when connected to fuel lines. Any other ideas?

Kevin

[John]

Some fuel filters are made to flow in one direction only. I doubt they are plugged already. Eliminate them temporarily and try it that way. You may have the filters on backwards.

[nashville_bill]

Pull the fuel lines of the carb side of the filters and see if fuel flows freely. The first filters I put on my bike were too restritive and did not let the fuel through without a fight. I bought different filters and have had no more trouble.

By the way, the ones I am using now are sold at Walmart, are metal, have 5/16" inlet and outlet and are for Ford trucks. I don't remember the number though.

[scalded dog]

Screens before the float valve may be plugged again, that could be a real possibility, especially if the filters inside the tanks are missing or part of the screen on the filters inside the tank is torn off. Later 'Dog

[Pat Kelly]

When you open the gas cap does the fuel flow then? I had about the same problem on mine. It would run great for about a quarter mile then barely limp home. Vent hole in fuel cap was rusted over.

[Redbaron]

Fuel flow problem

I have several friends who work at the local Honda/Yamaha shop which used to be Hunter Honda by the way, about 15 years ago. Sorry, I am getting to a point here. We see this problem all the time, someone puts the bike away with gas in the tank. Now it is puzzling to me why this happens, but old gas will actually turn to a gel type substance, and if you run the bike it will gum up everything from the tank to the carbs. The easiest way to clean the tank is to pressure wash the insides out, strip everything you can remove and take to a pressure car wash and blast the heck out of the inside, you'll be surprised at the gunk, rust, etc. that will come out. Now that was step one, after you fill it with water flush it with alcohol this will clear the water and if you leave some moisture it will actually mix with the water and make it burn, similar to curing small amount of water in a car tank, old mechanics trick. Then while you have the petcocks out clean the screens, turn them to prime and check the flow, fuel or whatever you use for this should actually gush out, if not disassemble and clean the petcocks they're fairly durable and rebuild kits are still available. Reinstall your tank close the lid and try this again, you may need to clear the vent hole on the tank, yes it has one but it is not readily identifiable if tank is rusted. It is located about center of the metal plate with the o-ring on it, use a paper clip to clean out the hole this should fix a venting problem if you have one. These tips are readily available here if you do a search for fuel flow problems, so if I missed something or you need more help search the site or feel free to e-mail me with any questions. I am on the board at 5:30 am and again after 6pm CST. Oh, one other note when you buy filters make sure they are recommended for gravity flow fuel systems, many newer ones are not, lawn mower types work well, they are small with a paper element, and trap a lot of rust, etc and are the proper size for our fuel lines, clear ones so you can see what is happening. HTH

[sidecarKev]

Over the weekend I switched the routing of the fuel lines around and got the fuel to flow decently. As far as I can tell nothing was plugged. I think the problem may have been to little gas in the tank. My fuel line kind of looped around and at one point may have been higher than the fuel level in the tank. I also put on my new seatcover, things are starting to take shape.


Kevin