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Post by pigpill on Apr 30, 2019 12:09:58 GMT -5
I am going to be installing a helper or starter pump for my ruckus clone. It has a fuel tank below the engine so I have had hard starting issues related to the stock vacuum fuel pump. Im not familiar with starter pumps and not sure if I should make the pump in line, or split off from the vacuum pump like I drew below.  |
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Post by 190mech on May 1, 2019 4:28:38 GMT -5
That will work,the check valves in the non running pump will keep the fuel from back feeding into the tank..
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Post by pigpill on May 1, 2019 8:53:13 GMT -5
Great, thank you 190mech.
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Post by jackrides on May 1, 2019 12:32:36 GMT -5
Is the pressure from the elec pump low enough to not overwhelm the float valve? A hookup test will quickly tell.
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Post by SMALL CC TEK on May 1, 2019 22:58:48 GMT -5
Is the pressure from the elec pump low enough to not overwhelm the float valve? A hookup test will quickly tell. If it does just toss a regulator in the only bad thing is the regulator will cost more than the complete fuel system ! lol |
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Post by FrankenMech on May 2, 2019 5:47:26 GMT -5
Use a low pressure electric pump made for motorcycles.
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Post by pigpill on May 3, 2019 9:03:49 GMT -5
I used a 2.5-4hp pump, I should get it today.
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Post by GrumpyUnk on May 4, 2019 8:07:42 GMT -5
Pig, you should not have problems with the original pump. Maybe check that there are no vacuum leaks, that the fuel in and fuel out lines are connected snugly. The ones I have seen can be connected 'backwards' reversing inlet and outlet, and the pump will struggle to deliver much fuel. It will deliver a small amount, but I don't think enough for use.
If the diaphragm is loose or has a pinhole, it won't move well enough to pump well. Make sure the screws are tight, and check that the diaphragm will hold vacuum. You can connect a length of tubing, suck on it, and block it with your tongue. It should hold the slight vacuum you created for a while, and if it leaks off quickly, your diaphragm is leaking. If you taste fuel, ditto.
An electric pump is really kind of overkill, and a lot of complexity for a problem that can be eradicated by making the original pump or replacement work to spec.
tom
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Post by FrankenMech on May 4, 2019 11:16:28 GMT -5
I believe the vacuum pumps are just barely 'adequate' even if they are in good condition. They will not work if connected backwards or if the vacuum line has any sort of restriction due to connectors, Tee's or splices.
However the vacuum pumps do work without electrical power drain. I have used an auxiliary switch to power mine but the Chinese switch shorted internally. My present setup powers the pump when the electric starter is engaged which provides quicker starts when the scoot is not used daily. If the vacuum pump 'fails' I can quickly connect the pump power wire to a key-on power line to limp home and avoid the 'walk of shame'.
It is still very very bad when the vacuum pump fails right in front of a biker bar...
It is still my opinion that vacuum pumps suck.
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Post by GrumpyUnk on May 5, 2019 16:51:21 GMT -5
If the vacuum pumps are that bad,I'd suggest a trip to a local lawn mower shop, or a cruise on ebay or amazon for a pump for a Craftsman equipped with a Briggs & Stratton. They use the pulses from the crankcase to operate the pump. Cheap too.
Start your engine, and feel the pulses from the cam cover vent tube. Remove the tube with the engine running at idle. That pulse will operate any pulse pump as used on riding lawnmower engines. These engines are in the 28-30-40 cubic inch range, giving good pressure pulse in the crankcase, but they demand more fuel also.
I think one would work as well or better than a vacuum pump.
I did connect the in/out incorrectly ona Dong Fang tricycle pump, and it did pump, but poorly with only enough output to run at idle with small bumps in rpm after waiting for fuel to arrive & fill the bowl.
tom
tom
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Post by FrankenMech on May 5, 2019 18:18:39 GMT -5
Those china pumps are that bad. To work backwards the valves must have been leaking. I have a Dong Fang R-trike  Thanks for the Craftsman info. I may have to try one when I move to a larger engine. The intake manifold vacuum pulse on a 50cc is poor. Hmmmmm I just happen to have a Craftsman rider sitting in the carport that needs lots of TLC or could be used for parts.
That pump that failed right in front of a biker bar was due to a splice in the vacuum line. It was a real head-scratcher. I had to deal with comments from the bikers and not a single one offered any help. Not long afterward I did rescue a Harley rider at a McDonalds.
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Post by GrumpyUnk on May 6, 2019 9:51:52 GMT -5
Frank I mentioned Craftsman because it is popular and common. If you look at many of these, they have what looks like a diaphragm cover with several hoses(3) attached. Fuel in, fuel out, and pulse from the crankcase.
I started the dong fang I was repairing, and its vent just went straight to atmosphere under the seat. It had very good pulses of pressure. One thing to remmeber I just thought of is that these mower engines also have a vent that leads to the intake manifold for emission control purposes. Previously the crankcases were vented directly to atmosphere, but they've now connected them to the intake, ABOVE the throttle plate, so no vacuum is involved, just a place to send the gases and also filter any air that gets drawn in.
On some, the pump is plumbed directly into the oil filler neck below the dipstick/fill cap. I figure those will not work so well if the oil level gets too high and blocks off the pulses reaching the tube. Some have converted mechanical cam operated pumps to the pulse type successfully. If I didn't mention, they are pretty cheap compared to a mechanical pump.
tom
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Post by FrankenMech on May 6, 2019 13:52:14 GMT -5
My Dong Fang valve cover vent tube just goes to my pod type air filter cover where the gases are directed into the intake through the filter. I suppose I could 'T' that off somehow and power the pump.
It won't get messed with until I install a new engine, IF surgery works.
I am having brain surgery later this month to see if they can fix my shaking hands. They call it Deep Brain Stimulation (DBS) with electrodes implanted in the brain. I am just a 'little' apprehensive about the surgery. My diabetes makes the surgery dicey. I don't have any other choices though.
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