Fuel pump flow rate

[tvmax]

Ok I finally got time to check my fuel pump. I put the output into a bottle and filled a 500ml bottle in 20 seconds. That should be plenty of fuel I believe. Fuel tank vent is not clogged and filter is new.
My problem is I can run up thru the gears to redline untill I hit 4th. Then it breaks up and rpms drop back to about 5 to 6 k. I also can go alon in first holding about 5 to 6k rpms for a few seconds then hit the throttle and it breaks up right away. Coast for a few seconds and I can run to red in 3 gears. Seems like fuel to me but... I have used different carbs, coils, cop mod, fresh plugs, new carb boots, and new diaphrams all to no avail. I am going to put in my other black box just to see. Last thing I can think of.
I am running rich with stock jetting. I just got new gaskets and o-rings for under the jet blocks. I will also put in 147.5 jets. I have an old hindle 4 into 1 and k&n filter. I dont think the jetting is causing this though.

Thoughts?

Jim

 

[one2dmax]

Have you checked float levels? Fuel Pressure? Does the fuel pump build up pressure and stop pumping? 147.5 would be pretty close for header install only.

Sean

 

[tvmax]

Floats are set. I didnt check what the output pressure was. If I put my finger over the fuel line it stops clicking. When I go to start the bike it gives a couple clicks unless it has sat several days then it clicks more before stopping. It all seems to work correctly. It does seem like fuel flow but maybe the electronic box is the culprit. There is no air leaks in the fuel lines.
Could being off in the jet size cause the symptoms I am having? Tomorrow I am putting the other jets, gaskets and o-rings in tomorrow. So I will see what that does. It would tickle me to no end if that cures the problem. If that fails I will swap my other box in and see.

 

[one2dmax]

Pump does sound ok. If you haven't already replace the plugs. Check the wires. Replace the filter and retest. That's all the easy stuff but it can be the black box too.

Sean

 

[tvmax]

The plugs have been changed, Different coils, Now COP mod, Different carbs, New filter. All no luck.

 

[Buster Hymen]

When I read your post the first thing I thought of was an electrical issue and not a fuel issue.

 

[naughtyG]

just a thought - you do have your fuel bowl vent hoses in place and routed properly, ending on either side of the air box near the top, right?

 

[Thevmaxrider]

just a thought - you do have your fuel bowl vent hoses in place and routed properly, ending on either side of the air box near the top, right?

+1 to that!! I had a guy last spring ask me to take his Max out for a ride as it was doing the exact same thing. Brought it back and lo and behold one set of bowl vent lines was kinked. Unkinked the lines and viola bike ran fine. Then I hit him with the list of other crap that was broken or worn out (thing had NO front brakes to speak of!!!)

 

[tvmax]

UPDATE!!! I changed the box and problem solved! Now to jetting. Progress!

Thanks all
Jim