Re: [T3] Still Blowing the Fuel pump fuse

[Greg Irick <gregi@vwtype3.org>]

>>A fuel injection pump runs at a constant pressure. Therefore, a constant
current.

Actually, the starting current of any motor is 7 times the running 
current.  Most small motors only draw a few hundred milliamps while 
running.  For a fuel pump I would expect it to draw around 1 amp at the 
most under max load while it's starting current is close to 7 to 8 
amps.  Now if the pump is sticking then the starting current will go way up 
since it is the counter emf (electromotive force) that reduces the 
current.  When the pump is first started there is no counter emf and hence 
the starting current is high.  Large motors use starting resistors that are 
in series with the windings of the motor armature to limit this 
current.  Just a little knowledge from my days as a nuclear propulsion 
plant operator.


Greg Irick
Silverdale, WA
gregi@vwtype3.org
gregandjenn@earthlink.net


'65 Notchback on a '69 pan with Britax sliding rag.  Soon to have original 
door handles and trim.  Plans for a 1776cc motor with a Berg 5-speed, 4 
wheel disc brakes with Porsche 2 liter alloys, Ruby Red paint and original 
interior.

'73 Pro Street Bug w/1915cc CB Perf. engine, Ultra Competition FI, Super 
Street tranny, Weld Racing Wheels with 195 50 15's in front and 265 50 15's 
in back with Type3 rear drums.


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