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+--- Thread: Increasing lift pump pressure via tougher spring / shimming. (/showthread.php?tid=7764)
Increasing lift pump pressure via tougher spring / shimming. - charlysays - 05-28-2017
Has anyone on here done this and if so could you please advise on what thickness of shims resulted in what pumping pressure?
At certain times of year I have low fuel pressure issues due to running on veg oil and making the pump more powerful should help this.
Any tips much appreciated
RE: Increasing lift pump pressure via tougher spring / shimming. - barrote - 05-28-2017
hello fine people,
I belive many people talk about the lift pump, springs and some other fancy gadgets that do this and do that ...
I belive a brief explanation on the lift pump subject will shade some light on the matter.
The lift pump is of the piston type, pumping action is done by Spring acting on the piston . A cam lobe cocks the Spring.
Cylinder is 24mm wide and the stroke 8mm, for every pump cam turn. If my math is ok every stroke is about 3500 mm square(less the coking pin 6mm dia). about 3cc for a 1000 strokes 3000cc. This alone should be enough for any super pump, considering that a 7.5mm at 150cc pumps out more or less 750cc, in 5 cyl config.
Besides the Spring there is also check valves in the system, being the one on the return line in the IP, the regulator of the system wich the stock ones are set for 500Mb.
I really do not know if changing the Spring to a harder version will improve anything, what i do know is that changing the return line check valve(return banjo) usually result in better performance.
In my opinion, for those who seek the lift pump tuning, the Spring along with the return banjo. Check pressures and guess...
Same happens for superpumps, usually unless a electric 300lts/h at 5bar is added to the system, engines do not pull well.
I belive is for some losses wich need to be adressed, and usually they are not.
i leave some pic about the pump.
RE: Increasing lift pump pressure via tougher spring / shimming. - barrote - 05-28-2017
can´t upload the picture , later on
RE: Increasing lift pump pressure via tougher spring / shimming. - hooblah - 05-28-2017
Get rid of it altogether and fit an electric fuel pump with an adjustable pressure reg.