Do I need a fuel pump ?

Kawboy post=34494 userid=599Getting back on topic......

All that being said, I would ditch the resistor and run the pump at full system voltage. I don't like seeing electric motors running at half voltage since they tend to run much hotter plus,  the resistor itself is eating up current for no reason. The charging system is taxed enough with all the accessories hence the dual alternators.

Hi Kawboy,
I've struggled finding a motorcycle sized fuel pump. Just as I was getting this Walbro sorted, to the extent that it is, the Moto Guzzi fuel pump arrived.  It's not that I'm satisfied with the resistor hack it's just that it's success has exposed the next deficiency. My adjustable pressure regulator won't adjust.
The problem (unverified but suspected) with the excessively powered pump is that it's either causing cavitation at the petcock or the vented pressure has the fuel so frothed up that bubbles are actually being drawn into the system. I chose to limit the electrical power but I could have installed a throttling valve in the line from the pump to the manifold.
What would you think of that option?
Thanks
Bill
 

KZQ wrote:

 

I could have installed a throttling valve in the line from the pump to the manifold.
What would you think of that option?



 

Not an option Bill. The pump is a positive displacement pump and snubbing it would cause the pump to stall out and burn out because of that.

Did you check the fuel filter screen on the petcock and insure that it is clear? If it is partially blocked, then that would explain why the pump is sucking air from the petcock. The pump would be struggling to pull fuel from the tank which would cause a vacuum in the petcock. Realize that the new pump wants to pull 3 times the amount of fuel from the tank. One way or another, the pump will work its butt off trying to do its job.

When the time comes, I'll be looking for an in tank pump from either a FJR1300 or a GSX1300 (probably the GSX1300) and retro fitting it to the tank. Size wise, either will fulfill the need . I have to be careful with the electrical draw since I have a 1980 B2 with a single alternator. Fuel injection will really start loading up the required electrical load and I have to be mindful of that.

This is why I keep hounding on " Fit, Form and Function" Once you start modifying things, you have to realize that the mod will have an effect on more than just its own system. All you wanted to do was replace a bad pump and now you're dealing with a fuel pressure / flow problem at the inlet to the pump and the outlet from the pump. Then there's the unknown possible problem on the electrical side. Wiring to the pump adequate for the increased load? Fuse that supplies the load adequate for the new load? Fortunately, the only thing the DFI interfaces with the pump is turning the power on or off.

 

I've made some progress on my Voyager. I've replaced the modified original pressure regulator with an AEM unit, which is actually adjustable. So far it's working well. Unfortunately the next step, plug readings, will have to wait until I replace these 30 year old tires.
The pod air filters make nearly as much sound as the exhaust. 
Here's a link to a video of me checking it out:

The bike sounds muddy off the line but it's pulling smoothly.
Bill

How fun! Set a camera on the curb, run up and down the street, get the dawgs a'howling and let the big 6 growl too!

...and yeah, she sounds a bit froggy right off idle but hard to hear authentically from the video.

keep going!