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fuel pump
by: jerseyboy - Apr 12, 2015 10:47:09 GMT -5
Post by jerseyboy on Apr 12, 2015 10:47:09 GMT -5
You need to figure out what thread you have on the tank then find an adapter...wonder if they used standard pipe thread in there..if thats the case would be real easy to do.If not you may be able too pull the guts out of the original pump/petcock so its just a passive part,,not sure how they look or work on 50's.
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fuel pump
by: tvnacman - Apr 12, 2015 10:50:09 GMT -5
Post by tvnacman on Apr 12, 2015 10:50:09 GMT -5
Does the barb have a valve on it? Wouldn't the manual shutoff do the same thing as the barb if you never shut it off.
John
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fuel pump
by: jerseyboy - Apr 12, 2015 10:52:02 GMT -5
Post by jerseyboy on Apr 12, 2015 10:52:02 GMT -5
I don't see how a fuel shut-off valve is going to solve whatever the problem is. All the petcock does is open up when vacuum sucks the diaphragm--- the vacuum isn't literrally sucking the fuel itself. It's just opening (sucking) a door to let the fuel in. Neither the petcock nor the shut-off valve are forcing anything. The problem has got to be somewhere else, IMO. You are right onewheel! The original problem sounds like a float or needle valve issue,,or fuel going back down the vacuum line into the intake....but if he replaces the petcock with a valve that will eliminate the vacuum line if thats the cause... |
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fuel pump
by: lain - Apr 12, 2015 11:15:00 GMT -5
Post by lain on Apr 12, 2015 11:15:00 GMT -5
I don't see how a fuel shut-off valve is going to solve whatever the problem is. All the petcock does is open up when vacuum sucks the diaphragm--- the vacuum isn't literrally sucking the fuel itself. It's just opening (sucking) a door to let the fuel in. Neither the petcock nor the shut-off valve are forcing anything. The problem has got to be somewhere else, IMO. You are right onewheel! The original problem sounds like a float or needle valve issue,,or fuel going back down the vacuum line into the intake....but if he replaces the petcock with a valve that will eliminate the vacuum line if thats the cause... Yeah, and ontop of that the manual petcock will make diagnosing fuel issues easier, and I won't have any vacuum lines anymore once I install the manual petcock, so that also eliminates any problems with vacuum lines down the road. I solved the initial problem by moving the needle, but without the extra gas I was getting before I am losing out on the high end a little bit. I feel I need something between a #  and #  main jet to get the high end performance back up to where it should be. |
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fuel pump
by: lain - Apr 12, 2015 11:18:38 GMT -5
Post by lain on Apr 12, 2015 11:18:38 GMT -5
Does the barb have a valve on it? Wouldn't the manual shutoff do the same thing as the barb if you never shut it off. John Yeah, but I will be using it to diagnose fuel issues whenever I have them, and eliminating the vacuum operation for the fuel seems like a plus to me. No more worrying about if the petcock diaphram has torn and is giving gas down the vacuum line or anything weird like that. Do you know the size of the threads on the standard petcock for top rear positioned gas tanks? My petcock is ont he bottom of my tank. I also have my old petcock, but I do not know how to measure or tell what threads are what besides telling you if it is fine threading or not. |
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fuel pump
by: onewheeldrive - Apr 12, 2015 15:36:53 GMT -5
via mobile
Post by onewheeldrive on Apr 12, 2015 15:36:53 GMT -5
Yeah most of those jet kits jump from to . |
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fuel pump
by: onewheeldrive - Apr 12, 2015 15:40:56 GMT -5
via mobile
jerseyboy likes this
Post by onewheeldrive on Apr 12, 2015 15:40:56 GMT -5
I don't see how a fuel shut-off valve is going to solve whatever the problem is. All the petcock does is open up when vacuum sucks the diaphragm--- the vacuum isn't literrally sucking the fuel itself. It's just opening (sucking) a door to let the fuel in. Neither the petcock nor the shut-off valve are forcing anything. The problem has got to be somewhere else, IMO. You are right onewheel! The original problem sounds like a float or needle valve issue,,or fuel going back down the vacuum line into the intake....but if he replaces the petcock with a valve that will eliminate the vacuum line if thats the cause... Yeah he mentioned his vac line was dry. The vacuum petcock should be ok if the vac line was dry and/or no gas came down when sucking the line by mouth, and if the gas stops when no vacuum is applied to the petcock. If the line itself is good and clamped on matters. Who knows, lol. |
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fuel pump
by: lain - Apr 12, 2015 16:07:47 GMT -5
Post by lain on Apr 12, 2015 16:07:47 GMT -5
You are right onewheel! The original problem sounds like a float or needle valve issue,,or fuel going back down the vacuum line into the intake....but if he replaces the petcock with a valve that will eliminate the vacuum line if thats the cause... Yeah he mentioned his vac line was dry. The vacuum should be ok if it was dry and/or no gas came down when sucking the line by mouth. Who knows, lol. Yeah, the pump seems fine, but I just want to simplify it if possible and make it easier to diagnose issues later. |
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fuel pump
by: rdhood - Apr 12, 2015 18:29:52 GMT -5
Post by rdhood on Apr 12, 2015 18:29:52 GMT -5
things are too cheap to screw around with it very long. If its the original fuel pump, you want to replace it anyway. Why not get a mikuni or an electric fuel pump for $25? It does two things... removes this as the issue for this problem, and gets rid of a future problem with a quality replacement.
I'd only consider a manual petcock if it was EASY to get to and operate with winter gloved hands.
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fuel pump
by: jerseyboy - Apr 13, 2015 6:18:53 GMT -5
Post by jerseyboy on Apr 13, 2015 6:18:53 GMT -5
My manual was super easy to get too,,just reach under the left side and boom it was right there.
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fuel pump
by: urbanmadness - Apr 14, 2015 15:59:38 GMT -5
Post by urbanmadness on Apr 14, 2015 15:59:38 GMT -5
Be carefull with this. Some have Vacuum pet cocks, some have vacuum fuel pumps. It depends on where you tank is. If the tank is below the carb, you have a pump of some sort. Most scoots use a vacuum driven fuel pump. If the tank is above the carb, then you will just have a vacuum petcock.
The big problem with the vac fuel pumps and vac petcocks is when you run at wide open throttle. At wide open throttle, the bike is not making enough vacuum to keep the petcock open or run the pump..
A manual petcock will fix this problem on scooters with the tank above the carb. A low pressure electric fuel pump will fix the problem on scooters with the tank below the carb. Upgrading the fuel pumps on those scooters with better vacuum fuel pump will not always fix the problem because at full throttle, they just don't have enough vacuum to run it.
Back to the original post.
If you overfill the tank, sometimes the excess fuel will get into the vent lines (emissions system equipped bikes) and it will try to pull raw fuel thru the vapor recovery system making them run rich. especially if the carbon canister is above the carb.
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fuel pump
by: lain - Apr 14, 2015 17:37:38 GMT -5
Post by lain on Apr 14, 2015 17:37:38 GMT -5
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fuel pump
by: urbanmadness - Apr 15, 2015 17:27:10 GMT -5
Post by urbanmadness on Apr 15, 2015 17:27:10 GMT -5
It would work if you had a bung on the tank (like a motorcycle).... Most of these scoots don't. You need a stand alone petcock. Just a ball valve with hose barbs for the inflow and outflow. then just plug it in, and cap off the vacuum line. You'll be golden. It will flow more then enough fuel.
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fuel pump
by: lain - Apr 15, 2015 19:58:24 GMT -5
Post by lain on Apr 15, 2015 19:58:24 GMT -5
It would work if you had a bung on the tank (like a motorcycle).... Most of these scoots don't. You need a stand alone petcock. Just a ball valve with hose barbs for the inflow and outflow. then just plug it in, and cap off the vacuum line. You'll be golden. It will flow more then enough fuel. What is a bung? Sounds dirty. |
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fuel pump
by: scooter - Apr 15, 2015 20:20:15 GMT -5
Post by scooter on Apr 15, 2015 20:20:15 GMT -5
It would work if you had a bung on the tank (like a motorcycle).... Most of these scoots don't. You need a stand alone petcock. Just a ball valve with hose barbs for the inflow and outflow. then just plug it in, and cap off the vacuum line. You'll be golden. It will flow more then enough fuel. What is a bung? Sounds dirty. You put it in your bung hole. |
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and #
main jet to get the high end performance back up to where it should be.
