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ViragoTechForum.com Tech Help xv400 fuel starvation (SOLVED)

#1:  xv400 fuel starvation (SOLVED) Author: jereme Post Posted: Tue Aug 24, 2010 4:00 pm

Hi, I have just got an old 1987 virago 400 which had been stored for 18 months in a garage.
After replacing plugs, oil, oil filter It rode great for 40 miles or so and then behaved as if it was running out of fuel, started backfiring, losing power and then stopped. It then would not restart for 5 minutes or so although the starter was turning the motor over.
When I got it home I discovered the fuel filter was clogged with rust. I eventually managed to remove the tank from under the seat and cleaned out all the rust using bolts. I replaced the fuel filter and fuel lines.
Thinking I'd solved the problem I started it up and it idled beautifully. When i drove up the rode it started again backfiring and losing power.
I have just replaced the coils leads and plugs and the symptoms are still the same.
Another new symptom (not sure if related) is that the signal fuse keeps blowing as soon as i put it in and I have not yet discovered where it is shorting.
I have just replaced the coils leads and plugs and the loss of power symptoms are still the same.
Any advice appreciated before i end up spending a fortune replacing everything.
Thanks
Jezz


Last edited by jereme on Wed Aug 25, 2010 9:53 am; edited 1 time in total

#2:   Author: webales Post Posted: Tue Aug 24, 2010 6:07 pm

Cleaning out "all the rust" from a fuel tank is usually not that easy. How did you do it using bolts? If you loosened up the rust and didn't get it all out, it will keep clogging up the filter.

#3:   Author: jereme Post Posted: Wed Aug 25, 2010 1:18 am

Hi, I spent most of a day shaking the tank with bolts and vinegar... rinsed , dried for several hours with a hair drier and then rinsed with petrol.
I put 2 new filters in the fuel line. At first some rust came out of the pump. I changed the filters again and they are as clean as a whistle after running the engine now.

#4:   Author: jereme Post Posted: Wed Aug 25, 2010 9:51 am

Woo hoo, I think i have solved this.
I found a wire shorting on the exhaust which i fixed. I then found the pump worked with the reserve switch to 'on' not just 'res'
Not sure why this is? But anyway i drove the motorcycle 10 miles with excellent performance and no problems...Hooray.

#5:  Re: xv400 fuel starvation (SOLVED) Author: grazingazer Post Posted: Wed Aug 25, 2010 3:43 pm

please read and heed: http://viragotechforum.com/viewforum.php?f=192

#6:   Author: parislan Post Posted: Mon Sep 06, 2010 9:52 am

jereme wrote (View Post):
Woo hoo, I think i have solved this.
I found a wire shorting on the exhaust which i fixed. I then found the pump worked with the reserve switch to 'on' not just 'res'
Not sure why this is? But anyway i drove the motorcycle 10 miles with excellent performance and no problems...Hooray.



Good afternoon, could you please provide me with more details about the fuel switch and wire shorting because my xv400 cannot "operate" on ON position.. just the RES the whole time... and sometimes it backfires or hesitates...

any photo with the problem or instructions would be appreciated

thanks a lot

#7:  Re: xv400 fuel starvation (SOLVED) Author: jereme Post Posted: Mon Sep 06, 2010 11:43 am

Good afternoon, could you please provide me with more details about the fuel switch and wire shorting because my xv400 cannot "operate" on ON position.. just the RES the whole time... and sometimes it backfires or hesitates...

any photo with the problem or instructions would be appreciated

thanks a lot

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The wire that i had shorting was the signal, horn neutral circuit caused by a wire infront of the battery touching and melting on the exhaust.
In the bottom of the petrol tank is a fuel level sending unit and i believe if its worn/ broken you will need to stay on reserve. To replace it you can remove the back wheel and just about reach the bottom of the tank or otherwise remove the petrol tank. The latter I did, but it is quite tricky. I found letting the air out of the rear tyre gave me just enough room to pull the tank through the fframe.
My bike ran great for a day or so and now the engine is running rich and terrible performance- too bad to ride. I think the carbs may need cleaning but not sure i am skilled enough to do the job Rolling Eyes

#8:   Author: parislan Post Posted: Mon Sep 06, 2010 11:58 am

Thanks a lot for the reply, i have several problems and i think that it is my tank in general, if i top up it everything goes bad: missfires, backfiring and others...
if i fill it half a way or so and "vent" it through the "cap" (open and close the cap every ride) there is no problem at all, except to the switch!
I did almost everything people adviced me in here and indead made it better (stp petrol treatment, float levels, new yamaha air filter etc) but if i fill it all the way up then the problems start.
I will go to a yamaha mechanic when i will find some time after all.
ViragoTechForum.com Tech Help xv400 fuel starvation (SOLVED)


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