Q&A Will not Idle
Note: At one time you could tell the AlternatorFuel Pump from the Generator Pump as the Alt.
pump was Tilted Slightly but not any more. The
Alternators Fuel pumps have the contact lever
protruding out the bottom of the pump about 3/16"
and the push rod is 3 7/8" long. -- As you can see
the Tilted Generator pump on the left made for
the Generator engine has the pivot pin higher up in
the pump body, All Generator pumps uses the 4
3/16" long rod. Use the wrong rod and you can
destroy the pump.
Fuel Pressure
VW states the fuel pressure should be 2.8 - 3.5 psi at 3400 rpm. Other manuals state 4 psi and
400cc/minute at 3800 rpm.
The cam on the lower part of the distributor drive lifts the fuel pump rod, which has a 0.160 inch stroke.
The distributor drive seldom causes any problems but there have been some soft fuel pump rods
produced.
If you put a file to the fuel pump rods pointed end and nothing happens its OK but if it cuts at all you
have
a soft rod and it should be replaced.
One other thing that can effect fuel pressure is adjusting the distributor drive end play.
This changes the distance the fuel pump rod extends out of the phenolic base.
The only way to accurately check the fuel pressure is "T" a gage
into the line.
The pressure can be adjusted by adding gaskets under the fuel pump phenolic block to decrease
pressure or by removing a gasket to increase the pressure.
The fuel pump block can be shortened by sanding the top surface but this is not normally needed.
Be aware when you reduce the pump pressure by adding gaskets you will also be reducing the volume.
With Weber or Delorto carbs its best to use a adjustable Fuel Pressure Regulator (#V105622) these
big
carbs are much more sensitive to fuel pressure then stock carbs.
Generator fuel pumps use the 4.18" long
rod and the alternator pump rod is 3.92" long.
Don't get them mixed up as you can ruin a new fuel pump with two turns of the crank.
For a simple test start with a Fire Extinguisher in one hand
pull the fuel line off the carb.
Have someone hit the starter. The fuel should squirt out 2 to 5 feet.
VW fuel pump delivers 400 cc/min at 3400 rpm and 3.0-5.0 psi
If it only pumps a stream out 6" to 8" then the pump is bad or there is some restriction in the fuel supply
line.
To test for restrictions, fill the tank fairly full, disconnect
the fuel line from the fuel pump and extend the
fuel line so the fuel can drain into a large gas can.
Check the size of the stream coming out of the hose when you start and then again after several gallons
have been drained out.
If the stream gets smaller then its time to check the tank vent or the fuel screen in the bottom of the tank
for restrictions.
Some owners replace the stock pump with an electric one (#V127001) but remember the elec. pump
keeps on pumping as long as the switch is on.
If you roll your buggy the electric pump keeps on delivering fuel even when the motor stops.
You can install an oil pressure switch that cuts the power when the oil pressure is low.
You might want to buy a spare pump as some of the stock ones only last a couple hundred thousand
miles. :-)
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Victor Comp. Products Inc. **--Vic's--**
Phone 816-650-3535 • 230 S Hudson St., Buckner, Missouri, 64016, US