Fuel pump / questions / Anyone use an external replacement?

[GD2]

Can fuel pressure that is too high cause carb leaks?

I measured the output of my fuel pump and it was almost 34GPH. I measured it before the petcock. If my pump is putting out too much pressure is it going out? Bad regulator?

If it is bad, is the Delphi P72190 (NAPA) the best choice? Or has anyone tried and external pump like the Mr. Gasket 42S?

Anybody know the specs on the fuel pump? PSI? GPH?

Thank you.

[GD2]

It looks like my manual says the fuel pump should put out 21.6oz per minute which (I think) comes out to just over 10GPH. So my fuel pump is really pumping it out.

[GD2]

I found this inline regulator - maybe a way to slow down the fuel is all I need?

https://www.amazon.com/PTNHZ-RACING-Adj ... 153&sr=8-6

[Rambozo]

Volume doesn't really matter as long as it isn't too low. However, pressure matters a lot. The stock pump is around 2 psi. That is hard to find, so often a pressure regulator is required to tone things down.

[GD2]

...The stock pump is around 2 psi. That is hard to find...

Yeah I have noticed that. This may be one of the times to bite the bullet and pay full price for an OEM Honda pump.

[GD2]

The regulator I bought was crap so no go there.

Here is what I am not sure about:

Beginning of story: Bike is running, no gas leak.

Get carbs rebuilt, runs fine for a while, then gas starts leaking. Tap the bowls, blow air into the gas line, still leaks. Bad.

Sent carbs back in, the float bowl needle filters are bad so they get replaced and I get the carbs back. Install them, now they leak worse. Like pouring out.
The carb guy is totally ready and willing to do anything to fix the carbs, but he tells me that if the fuel pump is pushing too high a pressure, it will cause the kind of leak that I am describing.

As mentioned before, when I do a flow test, the gas really gushes out and it feels like it is a pretty high PSI - a lot higher than the 1.5PSI "dribble" described in the manual. The flow test shows easily 3 times the flow rate.

My question is, would a pump "speed up" in its' dying days? I never had a leak with this pump until now. And I know the carb guy is top notch at what he does, so I have a hard time believing it is the carbs.

I have no problem spending the money on an OEM pump if needed, but definitely don't have an extra $400 to "find out".

HELP!!! (please...)

[Rambozo]

Don't guess, measure. While you can get a good idea of volume looking at fuel coming out a hose, it tells you nothing about pressure as it is at close to zero pressure with an open hose. You have to block the hose before the pressure will rise and will be highest at zero volume. All pumps have a curve between those two points. You can measure the pressure with a gauge or even just a length of hose.

h = 2.31 p / SG
where
h = head (ft)
p = pressure (psi)
SG = specific gravity (.7 for gasoline, 1 if testing with water)

[GD2]

Thanks - let's see if I get this.

Hang a piece of clear hose straight up to the ceiling. Pinch off the top. Turn on pump, mark the high point of where the fluid reaches on the hose. For gas, each 1.61' = 1PSI ?

[Rambozo]

Top of the hose is open, not capped and it's 3.3 feet per psi of gasoline.

[GD2]

When I was laying in bed last night I thought "I bet I got the math reversed"...

I will try that today - thanks again.

(and the ceiling in my workshop may not be tall enough)

[Jmicester24]

Try this pump. I bought it, works fine.

https://www.ebay.com/itm/305005585574?h ... R47Rxdj9Yg

[GD2]

Thanks for the link.

I just bought one of the Osias pumps (with the extra parts).

[GD2]

Just for grins I bought a 0-15 PSI gauge and tested my pump. It shows just over 3PSI.

[Rambozo]

Is that the Osias pump or the one you had before?

[GD2]

The old one that is still in place.

[Rambozo]

Thats a little high, but not the usual 5-7 psi of most automotive pumps that flood the carbs.
I would have thought 3 would be ok, but maybe 2 is the most those carbs will put up with.
I'm curious as to what your new pump does. It would be nice to have a known good pump since Napa has changed suppliers and that pump no longer works.

[GD2]

Well the "carb guy" said he thought 3PSI shouldn't be doing that much leaking so he is taking another look at the carbs to make sure the floats and seats are working properly.

As I mentioned, there were no leaks before the carb work. I trust the carb guy so I was hesitant to place blame on him, and I still trust his expertise. So in about 10 days I will see what happens.

The Osias pump was just a cheap way to see if there was a problem in the pump - something to compare. If it ever became obvious that the pump was bad, I would be tempted to spend the bucks on an OEM replacement.

I still really like the idea of converting to an external pump, but not sure how with limited space. If I deleted the petcock there might be room for one...?

[ct1500]

Unless you are getting around 1.5psi someone has replaced the pump previously with an automotive one. As to the why it leaks now is prolly because the float needles were replaced with chinlee junk or OEM were abused during the process or float level was not set correctly. Always use OEM float valves.