fuel pump pumping level

kanenas · Jul 20, 2023

This is for someone who has removed / repaired / replaced the fuel pump: Does the pump have a fitting / hose at the intake, with said hose / fitting capable of "falling out" and reducing the pumping capability to the 10-11 liters total? My bike died while cruising at low speed a couple of days ago and after the quick electrical checks were completed I filled the tank and tried to start, the bike started without any hesitation about 10 times in a row, without any failures. So it seems that I had ran out of gas, but, upon filling the tank, I was able to put in only about 11 liters!!!!.
So now I am wondering if I still have an electrical issue or if a disconnected hose has reduced the usable capacity of the tank.
Thanks in advance,
d.

TonyA · Jul 20, 2023

Yes , I have had my fuel pump out. There is not a hose at the intake , just a just a mesh filter sock near the bottom mounting plate .

kanenas · Jul 20, 2023

Thanks

So it looks like I might have some sort of issue and need to check the pump. My tank is fiberglass, any special precautions I need to take? Did you use a new gasket and/or adhesives during assembly?

cliffa · Jul 20, 2023

kanenas said:
Thanks So it looks like I might have some sort of issue and need to check the pump. My tank is fiberglass, any special precautions I need to take? Did you use a new gasket and/or adhesives during assembly?

Unless you have a non standard tank they are not fiberglass, but some kind of acryilic plastic, and are manufactured by Acerbis.
Anyway, to your problem, if you still have the standard relays, replace them with quality Honda / Omron units. ( see the alternate parts list) Also check for fractured fuses, and wires backing out of the fuse box, which are not properly latched in.

kanenas · Jul 20, 2023

No fiberglass tank! I guess I used the term in a generic way, it is some plastic. Do I need a new gasket / O ring or other sealing shtuff for reassembly?
Re relays, I have replaced two with Toyota items, got them at the local automotive shop, they are pretty standard in many cars and trucks.

City Garage · Jul 20, 2023

kanenas said:
This is for someone who has removed / repaired / replaced the fuel pump: Does the pump have a fitting / hose at the intake, with said hose / fitting capable of "falling out" and reducing the pumping capability to the 10-11 liters total? My bike died while cruising at low speed a couple of days ago and after the quick electrical checks were completed I filled the tank and tried to start, the bike started without any hesitation about 10 times in a row, without any failures. So it seems that I had ran out of gas, but, upon filling the tank, I was able to put in only about 11 liters!!!!.
So now I am wondering if I still have an electrical issue or if a disconnected hose has reduced the usable capacity of the tank.
Thanks in advance,
d.

If the hose fell off or the filter had a hole or anything else that would cause "pressure" loss and you would know it when you ride it. It might fine at idle. there are some threads here about checking a fuel pump recently

as for removing/replacing. drain fuel as much as you can by either using a switched relay and hose or siphon pump. I would replace the o ring but that's up to you if not lubricate it with two-stroke oil/dielectric grease/ vasiline whatever you might have.

Dont over torque screws or you will ruin your tank

City Garage · Jul 20, 2023

Also the intake for the pump is at the bottom so if your tank was half full then fuel level is not your problem

kommando · Jul 21, 2023

Working at a car manufacturing plant during the change from carbs to FI the dayshift came in to see a wall of cars that had been all pushed off the end of the line as non-starters and the line was about to be stopped. They were all the new fangled FI engined cars and the fix was to put more fuel in the cars at the fuelling station 3 car lengths before the end of the line. With the new fuel pumps the inlet was designed to higher than on the old mechanical pumps as the pressure had increased and there was a return flow so it was considered good for the pump life that it was not permanently pulling on the debris that would appear later on as the tank deteriorated. So a first fill of 1/2 gall became 1 1/2 gal.

kanenas · Jul 22, 2023

Funny thing about your numbers, they seem to match my 961!!!! In addition anothert question I have is about the two separate "bottoms" of the tank, one on each side of the main frame trube. Is therer any provision fir the right side to move over to the left? back in the day many tanks had that as the reserve side, with it's own petcock!

kanenas · Jul 25, 2023

Weell, I opened the tank. Everything seemed ok. The one problem I found was that the connector that brings the level sensor signal out has increased resistance in the ground wire. That is probably the reason I get no yellow light when turning ignition on. I did not take the connector apart because I want to research the zip tie holding the wires, don't need one to melt away inside the tank. I know that nylon should hold, but I don;t know if what I have is nylon.
With exactly 1 gallon in the tank the bike starts effortlessly. The plan is to just ride it for a while, see what happens.
With many thanks to all who helped.
d.

fuel pump pumping level

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