Help: Running issues

[Wesley]

Hi all, Little bit of history to start off then the problem.
I have recently become the proud owner of an FJ1200 1990, the bike was stored for 18 months but ran religiously every fortnight, when i purchased it i replaced the plugs,oil and air filters, and filled it with fresh oil and petrol. until now she has been running fine. 2 days ago I took her to nottingham (80 mile round trip) when i arrived i dropped her (i know stupid me) and when i say dropped i mean i parked,switched off, dropped the kickstand and dismounted as i got off the kickstand which wasn't down properly folded back up and she fell over  . The return journey went without a hitch.

Yesterday on my run home from work she cut out at approx 10mph as i was slowing for traffic lights - I tried to restart but she wouldn't fire (ignition was on, kickstand up, fuel in the tank, neutral selected and light on) The engine would turn over fine but she just wouldn't fire. I called a mechanic who took almost an hour to arrive, when he arrived she started just fine and ran sweet as a nut.

Today on my journey home i stopped for fuel, after refuelling she wouldn't start again.. same as before just turning over but not firing. After about 30 Min's or so I tried again and she fired and ran OK until i was halfway home then she started popping and misfiring, I managed to coax her home and left her for an hour. Now she starts fine again.
I have checked the fuel pump and can hear it ticking away so i know thats working, I dont have access to tools until sunday when i'll take it to my brothers garage (unfortunately he knows cars not bikes) But, any tips or pointers you can throw my way would be helpful.

Thank's.

[Flying Scotsman]

Gas tank has to vent look at the flapper valve.

[FJmonkey]

Easy to check if the tank is not venting, leave the cap open on your next few rides (not on a full tank, 1/2 or less). If it happens with the cap open then it is not a tank venting issue. I was having fuel related issues (acting starved). It took several rides to get enough information to figure out that the vacuum valve on the petcock had a leak. This is also easy to check. On your #1 carb, left side, you can pull the vacuum hose off the the intake manifold and suck on it. You should be able to get a little air to suck out then it should feel solid. If you can keep sucking air then you have a failed diaphragm that needs fixing or replacing. Let us know what you find out.

[Wesley]

OK thanks monkey and Scotsman I'll check the vacuum on sunday when i have tools available, unfortunately she now has a full tank of fuel so i cant run to work with the filler open. Would i eliminate this by just opening the tank flap next time the problem occurs?

[FJmonkey]

OK thanks monkey and Scotsman I'll check the vacuum on sunday when i have tools available, unfortunately she now has a full tank of fuel so i cant run to work with the filler open. Would i eliminate this by just opening the tank flap next time the problem occurs?

Yes, you can simply open the cap. But remember, if you ran the bowls dry, you will need to crank the engine to create vacuum for fuel to flow. So don't expect a quick restart.

[pdxfj]

He's got a '90 so his bike has a fuel pump...

[FJmonkey]

He's got a '90 so his bike has a fuel pump...

No vacuum control on the fuel?

[fj11.5]

If its not fuel related, have you checked your coil plug connections , could be dirty or loose

[pdxfj]

No vacuum control on the fuel?

If memory serves me the 89 and later bikes do not have a vacuum controlled petcock since the fuel pump controls the fuel flow... Someone please feel free to correct me if I am wrong.

When he turns the key on, the fuel pump should start clicking until it is done filling the float bowls.

[weymouth399]

That is correct, fuel pump will cycle for a couple seconds. You may need to turn key on and off a couple times to fill bowls.

Bob W

[FJmonkey]

Where in the hell are my manners??? 

Welcome Wesley, glad you could join us. I think you have already found us to be helpfull and generally friendly. Be ready for the occasional shit stirring that happens when we get antsy for excitement because the weather is keeping us off our FJs. Just roll with it or grab some digital popcorn  and watch the action.  Not as fun as getting your Kookaloo on but we need an outlet when we can't ride and all the winter mods are done. Not that I suffer from that here in SoCal where I can ride year round...

[Arnie]

Really sounds like a heat related electrical issue, not fuel supply especially since it occurred immediately after re-filling the tank.
Check the coils resistance and the voltage getting to them.  You might want to run a relay to give them full 12V power for fattest spark. 

Welcome,

Arnie

[RichBaker]

I'd have to agree with Arnie.... No vacuum petcock, fuel pump and the fuel pump bikes don't typically have an issue with the flappers.

[Wesley]

Where in the hell are my manners??? 

Welcome Wesley, glad you could join us. I think you have already found us to be helpfull and generally friendly. Be ready for the occasional shit stirring that happens when we get antsy for excitement because the weather is keeping us off our FJs. Just roll with it or grab some digital popcorn  and watch the action.  Not as fun as getting your Kookaloo on but we need an outlet when we can't ride and all the winter mods are done. Not that I suffer from that here in SoCal where I can ride year round...

What do you mean 'Weather is keeping us off our FJ's' and 'CAN'T RIDE' ?? what are ya a man or a mouse 
Only kidding thank's for the welcome guy's and for all those tips. I'm happy to report she's took me to work and returned home safe and well with no hiccup's but i'm still planning on taking her into my brothers garage on sunday where we shall take off the fuel tank (get it outta the way) and start checking everything.

[movenon]

Welcome ! I would check for a pinched/restricted fuel line and also under the tank (attached to the tank) there should be a small fuel filter. I would replace that also. If you don't have a Yamaha dealer close by then try NAPA for an equivalent filter. It's just a small in line gas filter. From the filter to the pump make sure the fuel line isn't pinched or kinked. It is easy to pinch in that area especially if the fuel line is old or weak.
When you turn on your ignition switch you should hear the fuel pump clicking for a bit until the carb bowls are pressurized. Not that the pump is the problem, just one thing to listen for routinely and in troubleshooting. It could be sticking or electrically interment. IF the pump is the problem there are less expensive pumps to use than Yamaha's. Check the files section or speak up and I or some else can come up with some part numbers for you. Its just a Small low pressure pump used in many different applications.
And as mentioned when you have the tank off check all the electrical connectors.
I can't say anything about how the fuel tank on 1990 lets air pressure in at the top of the tank as I have never had my fuel cap apart to study it. There is a vent/overflow hose attached to the tank (make sure it is clear of crap like bug nests etc.). Details, details.... Take nothing for granted.
I think your problem will be easy to solve even if you have to clean up the carbs. It's all fixable and there is a lot of help out there. Its one of the best things about owning an FJ. Good luck and keep everyone posted as to what you find out, it might help me or some else down the road.