dellorto fuel pump

[barneypeter]

this question is for a freind who is running a px with polini 180 sip pipe dellorto 28 phbh it suffers a little fuel starvation,how ever when he bought it it came with a vacume operated fuel pump,does any one know how and where these fit or where i can find destructions for fitting,cheers peter

[gaz_powell]

i fitted a mikuni one onto a vespa and it s the same principal there are 3 connections usually one on each side and one on the top

the one on the top operations the diaphram and is connected via a hose to outlet tapped into the crank case (i did mine just below the carb at the back)

then the petrol pipe from tank connects to the inlet usually arrowed inward and then the outlet is connected to the carb

i monted mine on the frame under the panel

the mikuni i used is as pictured - it worked a treat

[sean brady scooters]

typically what you will find is that if it was originally set up with a fuel pump the tap jet maybe only say a 200............which is fine if the fuel is pumped.......
if fuel pump has been removed........then the tap jet should be increased to 250......300 maybe..........

[barneypeter]

thanks guys most helpfull

[barneypeter]

hi adding to an old post i know but i now own the above mention scoot and it hasnt done any miles since so still has same prob,sean you said larger tap jet is this the inlet at the float or something else sorry to be a little thick,as i have been given the pump also has any one a how to guide for the drilling the cases or could it be fitted to the manifold ,thanks in advance

[LI150]

http://beedspeed.com/product_info.php?c ... ts_id=6710

[barneypeter]

ah yes,thanks for that li150

[gadgetman]

The problem with the vacuum fuel pumps is that they are much too powerful and the float valves in the carb can't regulate the amount of fuel entering the float bowl and so the carb tends to flood. The usual way around this problem is to restrict the fuel pipe diameter in some way ie pushing a large jet into the fuel pipe. This works ok on Delorto's but on others such as PWKs it is better to fit a small header tank next to the top of main tank and the pump pumps the petrol into this header and then is gravity fed down into the carb. As the header is high up in the bodywork below the seat there is sufficient fall to provide a constant and even flow. I have this system fitted to my Quattrini M1xl by Martin at Chiselspeed and it works perfectly regardless of engine speed, throttle position etc, apparently it's a system they use on the bigger race auto's.

[T5-190]

This might help.

[yam-lam]

got this image of ebay a recent scoot for sale on there