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Vstar won’t start

7K views 13 replies 5 participants last post by  nick57 
#1 ·
I ran out of fuel a few days ago (50ft from my house) tried the reserve tank but got nothing, refuelled the bike but it wouldn’t start. It cranks, but won’t turn over. Also the fuel pump no longer makes any noise when I turn the key (it’s not priming)

I’ve checked:
Battery
Fuel pump relay
Fuel lines

Next on the list is to make sure the fuel pump is actually working.
Is there anything I’m missing?
 
#2 ·
take the line off the fuel pump that goes to the carbs

turn the ignition key on and the kill switch to Run, fuel should come out of the pump output line

if not, take the line off the output of the fuel filter and make sure its not plugged

if nothing comes out of the fuel filter take the line off the petcock itself and see if any fuel flows there.

If your pump is bad you should be able to connect the output of the fuel filter to the carbs, bypassing the pump, then as long as you have more than half a tank of gas the bike will run. You need the fuel pump to get fuel out of the bottom half of the tank up into the carbs (they are higher than the bottom of the tank).
 
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#4 · (Edited)
something else that comes up

the electronic ignition needs 9 to 10V on the battery while cranking or you get no spark at all

if your battery is old and starts to fail, or if you crank the starter with a good battery for a long time (like being out of gas) and you pull the battery charge down
then you can get the situation where the starter is still cranking, but its cranking slower, but you are getting no spark at all because the battery is too low.

its very misleading because the starter is turning the engine over, so it seems like it should start, but it wont. If you get in this situation awaly from home you could also push start the bike. Then it will start because the starter motor is not pulling the battery voltage down.

If you check out the fuel and its all flowing, you might need to charge your battery up, or jump start the bike from another vehicle.
 
#5 ·
Battery was the first thing I tried. Had it on a trickle charger over night and it’s putting out more than enough power.

Main fuel line from tank to filter is clear. Carbs look ok filter is fine.
Just need to get back out there after work and check the pump. Ran out of daylight last night.
 
#7 ·
So I’ve now tried everything.
There are no blockages anywhere, there is power going to the pump. The bike is still cranking and with fuel line direct to carbs it’ll start. So I think the pump must be defective/dead. I don’t have a 12v supply to do a direct test to the pump.
So I’ll either replace it or find a way to test it... then replace it.
And side note, damn it’s hard to get the fuel pump out of my bike. Sheesh
 
#9 ·
... with fuel line direct to carbs it’ll start. So I think the pump must be defective/dead. ...

I think Les missed or didnt understand this part

the bike runs with the fuel pump bypassed, fuel filter connected directly to the carbs, with a full tank of gas

Pump took a dump

maybe there is crud in the fuel pump, I dont know if it can be cleaned out.
 
#8 ·
Before buying a fuel pump, try an old fashion test. Take fuel filter off and blow through it. Should be easy without much restriction at all. You might have gotten a bunch of gunk from bottom of gas tank trapped in the fuel filter. I had a simular issues once and just buy looking at the filter it was fine. I took it off and couldn't blow through it. I then started tapping it on a towel, here's what I found. Ran like a new bike after new fuel filter.

 
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#11 ·
I ws under the impression that a bike would always run if the tank was full, its only when its half empty that the fuel pump needs to push the fuel up to the carbs

but apparently there are different ways the fuel pump can fail? Sometimes it fails but lets the fuel thru if the tank is full,
sometimes it fails and blocks the fuel flow completely?

I dont know if it can fail both ways.
 
#12 ·
The Vstar fuel pump is similar to the one below except our inlet and outlet are on same end. If pump isn't turning the amount of fuel that can flow thru the turbine is extremely small. Also, a small amount of gunk that made it past the filter will clog the turbine. Quote about fuel pumps:
Insufficient flow limits cooling and lubrication of the pump. A leading cause of fuel pump failure is running the fuel tank low. This is particularly critical on late model vehicles without a fuel pressure return system. Running such a vehicle out of fuel once can permanently damage the fuel pump.

 
#13 ·
Cheers guys, despite doing some of the cosmetic work on this bike I am mostly learning the mechanical and electrical as I go. This isn’t the first time I have run the bike out of fuel as I have no gauges bar the speedo (only the second time) but it sounds about right it it can bugger it by running too low.
Having pulled the pump it looks battered too. Must be the original one from 20 years ago. Perhaps time for a new one.
Thanks again
 
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