Fuel Pump problems Tri-Z

[RiJiD-WILL]

I just rebuilt the fuel pump on my Tri-Z 85.5

I am stuck, here are a few pics to show you what I am dealing with. the new Diaphragm is solid plastic with a metal gasket on one side and a rubber gasket on the inner pump side. I put the plastic diaphragm in the middle of the gaskets on both sides of the pump, (I put it back together the way I took it apart.)
the trike runs but runs the same way it did before way lean like it has an air leak.

the carb is getting gas but the bottom end gas line has no fuel to it.
the diaphragm stops it all the ports on the pump are clean and when I put fuel in that lower line it runs Perf.

I am now stuck is this the right rebuild kit? should I just leave the plastic out of the lower end side so it gets fuel?

[Mosh]

So you are saying that when you dump fuel in the line going to the base of jug/cylinder, it Idles down?

If that is the case, you definately have a vacumn leak/ starvation for fuel.
There is not supposed to be fuel in that lower line. All it does it pulse the pump with vacumn, to feed fuel to the carb.

To check for vacumn leaks, start the engine so it has been running for just long enough to get warm.
Spray Brake Cleaner around your intake and base of jug and see if the idle comes down significantly. If it does in a certain area, you found your leak.
Keep a close eye on the fitting at the jug as they get loose and suck air also.
If you find nothing around the jug and base gasket or intake or head, remove the stator cover, then re-fire the machine and spray around the flywheel to see if the crank seal is sucking air.
I suspect you may find your leak at the base gasket..Z's are notorious for sealing issues there and the brake cleaner will point it out.
Be careful though..Brake cleaner is flamable on really hot surfaces. You dont have to flood the engine with it, just short bursts will be fine.

I see alot of Z questions on fuel pump failures, and it is usually the first thing to be blamed.
But honestly, I have never had or seen one fail, and only heard of a handful that actually have.

Also, have you determined that your carb cable is not holding your slide open some?
The stock cable sometimes would stick especially if you have that fulcrum box on the cable up by the tripple clamps.

Let us know what you find.

[RiJiD-WILL]

Thanks Mosh that is good news, the pump works since rebuilt. fuel was getting into that lower jug before I rebuilt it and I didnt know if it was supposed to be all fuel or just air in that line.

there are new lines from the pump but it was halfassed and some of the lines are old and I remember air was getting into the fuel line to the carb so hopefully thats my problem, the top end is brand new so I am hoping he put it together right and I dont have to take it apart..

thanks I feel better now that I know exactly how the pump system should work. I will order some new lines and if that doesnt work do the starter fluid test.

the throttle cable does have that fulcrum box and was high idle when I first got it home but I adjusted the throttle cable screws and that seemed to fix the idle not perfect but the air leak is my prob now.


Hang&Rattle this is the problem we saw with your tecate yesterday it just took a while to notice. Get the new gaskets and I will help put that beast together. I bet ya thats all it needs.

[Tri-Z 250]

get an 86' Z cable and eliminate that stupid box...it might make your thumb a bit stiffer. I've never used them less adjustable parts less hassel. I did take Mosh's advise on this current build and went Honda 400ex thumb control and 86'R cable to work the 39mm fuel dumper(way bigger spring).

[hang&rattle]

Cool beans! Thanks Will. Yup we were right on the crank line activating the diaphragm to push gas to carb, thanks to you, Mosh, we really need to get these MT 2-strokes lined out, hard with the elevation n' all.

[Mosh]

No prob guys.
I just got to thinking.
Someone may have LEANED that Z carb out to compensate for the ruptured fuel pump leaking into the jug.
You may want to check your jets before you get too involved, just to be sure someone wasn't tinkereing for the bad fuel pump.
That is if you just got this machine recently and dont know the history.

[RiJiD-WILL]

hey mosh I think you are right on it.

I put in the new lines, then went to kick start and test the fix and my kicker broke, I now have a new lever went to test it today and the air bubbles feed out of the line and looks like no new air bubbles are getting in but she will only run on half choke with the choke all the way in she runs really high idle but has alot of smoke like its a little rich but sounds like its lean and reving way high,
I did the starting fluid test and there was no change it seem like the adjustment screws on the sides dont make much difference either.

going to take the carb off tomorrow when my hand stop shaking. been messing with these trikes all day.

[Bryan Raffa]

pilot jet sounds clogged.. now get the numbers of the jets when you got it apart.. you will be going by the 85 carb spec's

[RiJiD-WILL]

carb looked great inside jets were clean the pilot jet was a 40 (stock is 45) the main jet was a 450 (stock is 470) the needle jet was stock at 6H3 the manual says 6H3-3 but I am not sure I saw a -3.

I am going to get the stock jets hopefully today and try it out.

[Just-Tri-It]

carb looked great inside jets were clean the pilot jet was a 40 (stock is 45) the main jet was a 450 (stock is 470) the needle jet was stock at 6H3 the manual says 6H3-3 but I am not sure I saw a -3.

I am going to get the stock jets hopefully today and try it out.

I believe the -3 refers to the clip position.

[RiJiD-WILL]

ah that makes sense the clip pos. is on 3.

I also fixed a C-clip that was missing, it holds the throttle cable housing in the top cap of the carb. so maybe that being loose and sticking out was helping let air in.

going to bring the carb into the shop tomorrow and get the stock jets.

[RiJiD-WILL]

PROBLEM SOLVED! it was the jets in the end brought them back to stock and she screams.

so the final problem fix was

1 - bad fuel pump diaphragm letting fuel into the crankcase.
2 - previous owner reduced the jet size to compensate for extra fuel.
3 - and bad fuel lines on the reserve side.

Fix

new fuel diaphragm kit, fuel lines and stock jets.


awesome guys thanks for all the help!!!!

[Mosh]

Awesome...
And thanks for posting the fix..All to many times, people just never post the fix, and the next guy looking for answers doesnt get one in a similar problem search.

Now go enjoy that sucker..Z's are blast to ride.