Tri Z acts like its running out of gas

[Darius1502]

My Tri Z (as usual) is acting up.

It runs fine but sometimes it will just run out of gas...but of course there is plenty of gas in it.

If I try to stab the throttle it blubblers. I have to roll the throttle on.

Any ideas? I thought it was the fuel pump since its hard to start when cold.

Thanks guys!

[Dammit!]

That R sitting in there next to it is just making it feel insecure. :D

[Darius1502]

I hate the Tri Z under the seat tank crap.

That thing has given me more grief. Tim's great knowledge regarding blowing on the line actually works. That guy is a true asset!

Tim whatever you tell me to do, I'll do it!

[Dammit!]

What have you done so far to troubleshoot this problem? The first things to do would be check the float adjustment and seat. Either of those not being right can cause that. The other thing is obviously the fuel pump. Do you have a way of rigging up a small amount of gas that can be gravity fed to the carb to see if the problem is still present?

[TimSr]

I agree with checking the float needle operation.

The fuel pumps rarely fail, but the most common problem with them, is not the pump itself, but the vacuum hose running between it an the jug. If it gets a crack or something, it will leak vacuum, but often it goes unseen and unoticed.

The pump is very simple, and you can open it and visibly see if there is anything wrong. The rarely fail, but often get blamed.

Another problem i ran into on my quad Z was it would occasionally "run out of gas" on uphill climbs. Had me baffled for a long time, Turned out to be small piece of foil from an oil bottle seal about the size of a dime, in my gas tank moving around in there. When I went uphill, it might find its way to get sucked right over the gas line hole. When the engine would die, suction ended, turned it loose, and aslight jiggled moved it right back off the hole again. There is no tube sticking up where the gas lines connect in, and anything in your tank can cover a hole, esepcecially when angled uphill.

One other similar problem was caused by a clogged gas tank vent tube, but if you can blow through it, its good.

[Darius1502]

1) Vacum Line: Check the hose completely. Took it off and visually no cracks or holes. Blew air into it. No cloggs. Put my finger over one end and blew air into it. No leaks.

Secured it to cylinder and fuel pump. Fit is tight and put Yamabond around fitting.

2) Took carb off and check float bowl and level. Hooked carb to a auxillary tank and tested the float valve. It works good. When the float is down the gas flows out at a good pace. Enough to fill the bowl quick. I even adjusted the float level so more gas would be in the bowl before it cuts.

3) Blew air through the vent hose. You hear bubbles, etc. The Z won't start this way. I still have to put gas through the boost bottle line.

4) Fuel pump: Changed the diaphrams. Made some out of 'tear off's'. Can see gas flowing through my fuel filter when she runs.
I don't know what to do with this thing. Sometimes I think Z's are great and other times a POS.

[asc180]

Check the nipple on the jug where the vacuum line for the fuel pump is. On mine that nipple came out one time and would fall out when back pressure built up. If it comes out a little or it is cracked that could be your problem.Just my two cents.

[RabidPitWeasle]

Check the reserve fuel petcock just behind the fuelpump, you can pull the sediment bowl off theres a screen inside sometimes that gets glogged up with crap and will give probs, happened to me awhile back I took the tank off and flushed it out to get any other crap out.

[Derrick Adams]

Darius, don't store your bike on its back and then expect it to start when you drop it on it's wheels. The reason you have to put gas in the boost port is because of this. Your bowls will empty every time you do this.
Actually, this may empty your whole fuel system, from the tank to the carb.
This may also put fuel in the vent lines and cause airflow issues to the tank.

[Darius1502]

good point Derrick. My Z always has given me trouble even before I stood her up.

I am going to re-build the fuel pump with a factory kit....then see what gives.

[4cylinders]

hey, anybody ever test the vacuum coming from the engine? also yamaha carbs have a really weird enrichment circuit, have someone cover the carb intake, choke it, if it starts, then the problem is in the enrichment circuit.

[Lots_Of_Nothing]

Hey.. Well it sounds like you covered the basics, but there is also some other simple things to check, Reading your posts like this reminds me why I sold my Z a long time back, LOL!. But anyways, not to discourage you.. Heres some things to check;

-Throttle cable (check for kinks and all that, I know it sounds dumb, but make sure it is allowing the carb slide to completely bottom out)
-Reeds
-Carb boot
-GASKETS!, check them all, a simple leak anywhere will cause it to run like crap, check the intake gaskets, and the base in particular (cylinder to bottom end).
-Correct size fuel / vent hoses, Have you ever replaced them? Sometimes people stick bigger sizes then stock on and it wont let enough vaccum form.
-Flush out the fuel tank and make sure it is CLEAN inside.
-Maybe your just jetted too lean?
-Hose clamps, make sure the lines are clamped good on both ends.
-Your bikes sit alot , are you sure the gas isnt old and just not burning correctly?
-What fuel mixture are you running?
-Clean all fuel filters.
-there is a good chance the carb is just not functioning properly, so do you have an extra you could throw on to test it?

I would save your fuel pump for last, unless it is leaking I highly doubt that is the problem. I can remember having to replace basically everything on mine.. But never the fuel pump.