Running woes

[Plug]

Eventually, its sorted.  Turned out to be the fuel pump relay type thing. The pump was pumping fuel when you turned on the key but wasn't doing anything afterwards. Simple solution, run the fuel pipe direct from the tank into the carbs. Sorted. Took it out for a good blat and no probs Thanks for all the advice. I now know a lot more about my bike than I did a few months ago

[jack02]

Nice one,Plug. Do you intend to leave it like that - having the carbs fed directly from the tank with no pump in the way? Reason I ask is that a rust-inside-tank scenario has manifested itself on my bike. My fault for leaving it half-full over the UK winter....  Symptoms manifested with a stumble just off tickover and the odd coughing backfire. I've pulled the carbs and the float bowls have a sediment of rust. I've just drained the tank and it really ain't that bad at all,but I'll have to rectify it regardless. Anyways,I drained the tank with the filler cap locked and the fuel flowed extremely rapidly and uninterrupted - putting paid to my belief that the pump was necessary to keep up with demand at high rpm. I'm thinking of ditching the pump as you have done, as no doubt the innards will be as affected with rust as the carbs were. So guys,what's the pros and cons of running sans pump?

Thanks,jack.

[Travis398]

What turns the gas off when you turn the bike off?  What's the worse that could happen eh? 

[jack02]

What turns the gas off when you turn the bike off?  What's the worse that could happen eh? 

Hmm. Now you put it like that I'll stick with it.... but why did Yamaha (or anyone else for that matter) go to the trouble and expense of a pump when a vacuum-operated tap would suffice??

[Arnie]

I had my fuel pump die on me and after bypassing the pump the bike ran fine....UNTIL I was at just below 1/2 full.  Then it started missing and cutting out when at or above 100 kph (62 mph) steady cruise.
I've also had a previous bike with a vac operated petcock fail and fill the crankcase with fuel.  I was lucky to not bend a rod.

Cheers,
Arnie

[Plug]

Gonna fit an inline fuel tap. A lot cheaper  than a new relay

[Travis398]

Gonna fit an inline fuel tap. A lot cheaper  than a new relay

Perhaps, but what if Arnie is right? 

[Plug]

Fair point. Where abouts on the bike is this relay type thing. Silly question I know

[SlowOldGuy]

If you simply bypassed the pump by connecting the hoses at the pump, then you're making the fuel run back uphill to get to the carbs.  I'm running a "pump" set of carbs on my '85 that are only gravity feed and am having no problems with fuel flow.  For this application, the hose comes out of the petcock and goes downhill to the carb inlets.

If this is going to be a permanent setup, reroute the fuel hose to run directly into the carb inlet.  And install some kind of shutoff just in case.

DavidR.

[Arnie]

Fair point.  I did only bridge the fuel pump connections.

Arnie

If you simply bypassed the pump by connecting the hoses at the pump, then you're making the fuel run back uphill to get to the carbs.  I'm running a "pump" set of carbs on my '85 that are only gravity feed and am having no problems with fuel flow.  For this application, the hose comes out of the petcock and goes downhill to the carb inlets.

If this is going to be a permanent setup, reroute the fuel hose to run directly into the carb inlet.  And install some kind of shutoff just in case.

DavidR.

[Plug]

I've run it direct from the tank to the carbs. Will fit a shut off tap of some kind soonist