Tomos Sprint A35 fuel line crimping

Bethany Witten /

I have tried searching and I haven't found anything that quite answers my question. I guess I will start at the beginning: I have a 94 Sprint (upjet, biturbo, airbox removed) - I had it all last year and it ran like a champ. However, at the beginning of this season it was barely running- IF it would start it would bog down after a minute or when you gave it any gas. My friend and I cleaned the carb and adjusted the idle, put in fresh gas, and fiddled with the petcock. The fuel line was pretty hard (which I now know is normal for nylon line), so we replaced that also, and for the day it was ripping just like normal. We replaced the line with a vinyl tubing (I work at an auto shop and that was all we had to fit it at the moment), and the next day the ped was running badly again- it would bog out if you gave it too much gas.

Some local moped guys and girls (thanks to the bourbon bandits :)) checked it out and found the line was crimping at the curve that goes to the petcock. They replaced it with PVC line with a spring on it, and it was just fine for a nice long cruise that night.

Unfortunately, on my way home it started bogging again. I got it home and saw that the pvc was crimped. I do not know what the spring was for (I assumed to help KEEP it from crimping), but it did not seem to do the trick. I replaced this with automotive fuel line, and it didn't look like it was crimping because it was so much thicker, but it was still running badly. Yesterday I replaced THAT line with some more PVC (the hardware store was the only place open), and it ran like a champ for a while, but after a while it started bogging again- I checked the line and sure enough, it was partially crimped. So I know my problem is only in the fuel line crimping, not in the carb or otherwise.

SO. I just bought some tygon line, and I am going to replace the pvc with this. I wanted to know if someone could give me some insight on how to run it so that it will not crimp. The hard nylon line that was on there never caused it to do this (obviously), but I have been told that this should not be happening like it is. Also, does anyone know if there was a reason for putting a spring on the fuel line? Maybe that helps with keeping it from crimping? I am sure that I'm not the only person to ever have had this problem, what with Tomos' convoluted setup and all.

Thanks in advance

Re: Tomos Sprint A35 fuel line crimping

Don Pflueger /

i've owned hundreds of tomos peds and never had this problem. at least not that i can remember.

is the fitting on the carb that covers the little filter moving by any chance?

when you install the fuel line are you making it long enough that it doesn't have to make any sharp bends?

a straight shot is usually your best bet, but on these step through models i find that it is better to rought the fuel line so that it is in the most relaxed position possible and does not have to make any tight turns. and on the 94 models with the short intake, they can be a bit more of a challenge to do this. try loosening that fitting on the carb then run the fuel line so that there is no way it will crimp over time.

or get steel braided fuel line from your auto parts store lol.

Re: Tomos Sprint A35 fuel line crimping

Bethany Witten /

I was actually considering getting some metal fuel line, because this is a pretty big pita. It has to make an S shape in order to go from the banjo on the carb to the petcock - there is no way around that. I have tried making them long and making them short, it is just with the way it has to be routed a crimp seems unavoidable.

I guess I will try to adjust the banjo and leave the fuel line super long and coil it, rather than S it. Does having a rather long length of fuel line cause any problem with the bikes?

Re: Tomos Sprint A35 fuel line crimping

I'm not sure if your Sprint is set up like mine. here are some pictures of mine. Hope it helps.

Re: Tomos Sprint A35 fuel line crimping

Bethany Witten /

My banjo was pointing towards the front of the bike. I will see if I can adjust it to the back like yours- my line was going in FRONT of the carb, so maybe that will help out.

Thank you!

Re: Tomos Sprint A35 fuel line crimping

If you have any other questions, shoot me an email.

Re: Tomos Sprint A35 fuel line crimping

Don Pflueger /

i've never had a problem with the line being long. it helps eliminate tight curves that will cause acrimp. it's a gravity feed system, so as long as the fuel line does not drop lower than the float bowl you're ok.

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