fuel pump or lack thereof

[Harvy]

The pump is designed to pump fuel and in no way holds it back.

Not so......if your's lets fuel through when its not running then its broken!

Harvy

[ribbert]

New at this posting thing and new to site / newbie.  So I will try again to post this without the previous quote attached:

Good day all, I am on my 4th Fj and have stripped the fuel pump off every one and garbaged them. Funny thing is that I have never been stranded due to pump failure.  YAMAHA HA HA HA !!!

Being new to the forum you may have missed the very reason this is being discussed.
Gravity feed systems are in theory simple but in practice give a lot more grief than fuel pump models. Reliability? The fuel pumps should be good for 100,000 or so and enable you to run much better filtration.

Over the life of a model run manufacturers do many, many 'under the skin' modifications to address issues that show up with real world use, most you wouldn't even know about until you went to replace a part. Yamaha would have had good reason to fit fuel pumps to the later models. After all, it added cost and was hardly a selling point.

Being happy with the gravity system you bike already has is one thing but why go to the trouble of actually converting it back from a  fuel pump?

Noel

[movenon]

In response to MOVENON' s " Fire Risk" I would have to ask how fuel would leak passed the needle and seat just because there is no fuel pump. The pump is designed to pump fuel and in no way holds it back. If needle and seat are bad you have a potential Fire Risk but removal of pump in no way puts you in this category.

The fuel pump has a check valve to prevent fuel flow when no power is applied to it (designed safety feature). If that fails (and they do) the only thing keeping the fuel from filling the bowls and pouring out on the ground or garage floor are the 4 needle and seat valves (they fail even more often).

There are 2 unrestricted fuel flow safety's in both models of FJ . In a gravity feed model there is the vacuum control fuel valve (the engine has to be cranking or fired up to suck open the fuel control valve) located at the fuel tank , and finally the fairly reliable 4 needle and seat valves. Only takes 1 to not to seat and leak all your fuel out.

Now for a fire possibility ( all hypothetical ). You have the bike in your garage, shop, shed or other enclosed space and have some amount of raw fuel (up to 5 gallons) on the floor giving off fumes all night/day, and you might also have a furnace / gas or electric water heater or other ignition sources in the area to ignite this air fuel mixture. There are other ways that can also start the fire. Not saying it will happen but do you need to take the risk if you know better.

There is at least one member on this forum that lost his bike to a fire when fuel dripped onto his hot engine. If you ask nice enough he might post some pictures for you. I don't think his was a fuel pump model (?)  but leaking fuel and and an ignition source is the formula.

Which ever way you want to go, gravity or pump just do it understanding the complete system and why it was designed that way. Yamaha or any other manufacture doesn't put anything on a car or bike without a good reason.

I can put the cheapest, crappy, bald, weather checked 30 year old tires on my bike that I can find and it will run just fine. Trust me, it will.   If I get a bit more knowledge I might want to rethink the tire deal. Just because something will work doesn't mean it's a good idea unless you have a full understanding of what you are doing. 

George