Thread: Pulse line and my latest finding
10-23-2009, 05:27 PM #1
Pulse line and my latest finding
I have have not seen this discussed before, if it has, forgive me.
I have been meaning to post this for a while now.
I had a "customer" of mine with a carb problem. Just could not get the carbs to "work" right no matter what he did.
I checked them out, rebuilt them, replaced fuel filters, fuel line, pick-ups, everything. Still had an inconsistent problem. Changed f/a's, ran without them, other brands, no good.
The problem was it acted like fuel starvation. Could not duplicate very often, but when it did it, it would happen and then after the engine "stumbled" would be gone as fast as it came.
I checked on the water during use, on the hose. Just could not find it.
Then one day while just staring at the engine, I noticed that it had some of that "colored" fuel line on it. No biggie, I run it too. Thing is, this stuff was thin and very soft.
Well I had an idea.......replace the colored pulse lines, which I never did when I changed out everything else, and try some good old Yamaha lines. The kind it came with from the factory.
Long story short.....that cheap colored line was collapsing when used as pulse lines. The vacuum sucked it right in.
So in the end, not all colored fuel line is the same. What I use is very "stiff" compared to what the customer was using.
10-23-2009, 07:41 PM #2
Dayum, you got lucky taking a guess at that. Most would have never thought about it. Good catch and thinking.
10-23-2009, 08:41 PM #3
I never use that stuff for pulse lines. Even in the Mcmaster catalog it says that tygon line isn't rated for vacuum. The stock yami lines are a good quality line.
10-23-2009, 09:04 PM #4
The fuel lines from fuellines.biz CAN be used for pulse lines. I have had nothing but great results with it. They are thick enough to hold up to the negative and positive pressures. But again you are right I cannot say this about all colored fuel line. I have used fuel lines from fuellines.biz on my quads, snowmobiles, and skis with no problems.
10-24-2009, 09:51 AM #5
I won't mention where he got the fuel line, but I am wiling to bet that there are more than a few of you here who are running the same stuff.
I compared some he had new to what I have new, and what I use has a thicker wall to start with. Now I am not saying what I run won't have the same problem down the road, just what the visible differences are.
Comparing his used line with his new line, it is a little bit softer. I am chocking this up to fumes from the fuel. Mostly from the Ethanol in the fuel.
Take this for what it is, just my findings. Just do yourself a favor and check your fuel line often. Not just for loose lines, but also "soft", and collapsing lines.
One last important thing, always vent the engine bay before starting. This is the perfect time to check those fuel lines also.
10-24-2009, 10:47 AM #6
- Join Date
- Aug 2009
Ive been having carb issues ever since I got my xl700 The pulse line is origional. looks perfect. I tried to pull it off and the copper tube pulled out of the intake. Is this a press fit or glued in? The hose is glued on the tube.Any thoughts?
10-24-2009, 11:44 AM #7
A little 2 part epoxy and glue it back in.
Needs to be tight and not leak even in the least.
If you have enough slack, cut off the line, and reattach what is left over to the fitting, after it has had time to set up. The epoxy that is.
10-24-2009, 11:55 AM #8
- Join Date
- Jul 2007
- near Toronto, Canada
Keep in mind that the fuel system from fuel tank to fuel pump is also under constant mild suction from the fuel pump while the engine is running.
Fuel hose that is too soft can partially collapse and restrict fuel flow, especially where the line is tightly curved or pressed against something.
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