Off topic low pressure electric fuel pumps beware

[Edwin Dirnbeck]

For years,I have been retrofiting my large carbureted grass cutters and 4 wheelers with 12 volt electric fuel pumps.They put out about 6 psi max.I never had a problem.Right now I have a Polaris side by side and a Kawasaki mule that require a VERY LOW PRESSURE PUMP. They need a special pump that only puts out 1 to 2 psi.This had me going in circles. I rebuit the carbs and they leaked right past the float needle and seat. I bought new carbs and had the same problem. I finally stumbled accross an ad for an OEM Kawasaki carb that stated ,it had 1 to 2 psi max. I then found a few you tube videos where people were putting electric pumps on their SMALL riding mowers.They cautioned to use ONLY a 1 to 2 psi pump.Just when I thought that I knew EVERYTHING. I was wrong again. It only took me about 2 weeks and many gas soaked hands to figer it out. Edwin Dirnbeck

[Ed ke6bnl]

I have a mule 3010 that is good to know

[Doozer]

If you look at the FACET fuel pump web site
they list about 30 different cube style fuel pumps
ranging from 1 to 2 psi up to 12 to15 psi.
Just buy the right one.

-D

[Edwin Dirnbeck]

If you look at the FACET fuel pump web site
they list about 30 different cube style fuel pumps
ranging from 1 to 2 psi up to 12 to15 psi.
Just buy the right one.

-D

Doozer,thank you. My experience led me to think that all carburetors worked with about 6 PSI. I have been lernt. Edwin Dirnbeck

[Doozer]

Not exactly related, because it is gravity feed, but...
I used to play with Honda motorcycles. They typically
have Kehin carburetors. These carbs had spring loaded
float needles. Think like a very light spring inside the
center of the needle, that loads a little pin, which in
turn bears on the float. These suckers would never
seal right and flood out if you looked at them funny.
I have found the needles from Walbro LM series carbs
retrofitted into the Kehins perfectly. They are solid steel
needles, no spring loaded bologna. Lucky I knew a
small engine guy who had a junk pile where I could
get old Walbro carbs. Typically on older Tecumseh
engines had them.

-Doozer

[Edwin Dirnbeck]

Not exactly related, because it is gravity feed, but...
I used to play with Honda motorcycles. They typically
have Kehin carburetors. These carbs had spring loaded
float needles. Think like a very light spring inside the
center of the needle, that loads a little pin, which in
turn bears on the float. These suckers would never
seal right and flood out if you looked at them funny.
I have found the needles from Walbro LM series carbs
retrofitted into the Kehins perfectly. They are solid steel
needles, no spring loaded bologna. Lucky I knew a
small engine guy who had a junk pile where I could
get old Walbro carbs. Typically on older Tecumseh
engines had them.

-Doozer

Indeed,all of the carbs that I am fooling with now have the tiny spring pin float needles.Edwin Dirnbeck

[Robg]

Just an interesting (?) FYI on the spring pin on the float needle: it’s for off-road use where the terrain is very rough and incline angles may be high. My shop sold tons of replacement carbs and the Carter carb offered replacement needle and seat packs with the spring loaded needle. We sold them to 4 wheel drive off road racers that, obviously, ran in very rough road conditions. Apparently they worked quite well for this application. This was before modern fuel injection became commonplace.
The spring allows some independent movement of the float where otherwise the float and needle/seat arrangement would be forced open intermittently and flood the engine.
Concerning fuel pressure, we also sold electric fuel pumps and carbs generally couldn’t take pressures higher than 5 psi for street use as the pressure overcame the needle and seat seal and they’d flood. There were 7 psi electric pumps but usually only saw competition drag race use.
Doozer you’re right about Facet pumps and low pressures. Good info!

[Tobias-B]

Yuppers, even the venerable Weber DCOE starts to misbehave above a couple- 3 psi, and
with the advent of 'bigger is better is racing' fuel pumps, electric pumps can now
easily put out 10- 15 psi.

Just because bigger is better.

t
uses a regulator.

[CalM]

Low pressure pumps can be hard to find at the local auto supply. Fitting a return line at the carb fitting can be a fix for an over pressure fuel pump. Return line diameter/ length/ or any added constriction can customize the pressure seen at the float needle. Just make sure to put the return line on the BRANCH of the tee. making the return flow turn the corner. Otherwise, the venturi effect can suck the fuel OUT of the carb. (don't ask how I know this ;-)

[mixdenny]

I think all the carbs used on British sports cars were 3 psi. I added on an adjustable regulator when I went electric.