Fuel Pump Mods - I now all about them

[Cptsideways]

I have spent the past week (or so) playing with Bosch VE fuel pumps, the same as fitted to 80's (though they are Jap built Zexel's I think) & I now know all about their inner workings


I am building a "hybrid" pump for my Hymer camper as my god it's slow, 90bhp allegedly from a POS Lucas CAV pump, I think its nearer 50bhp if I'm honest so its going in the bin & being converted to the VE pump which is being built up from various other pumps to get the right selection of parts.


There a few things which will help with making em go.

Main thing is plunger size & I'm guessing the LC has a big 14mm one to start with ? Usually this is upgrade'able with a bigger hydraulic head but the LC might have a big one to start with. If it is this is pretty simple & a massive upgrade, I'm guessing the Yanmar marine applications use a bigger plunger & head for their 300hp.

Next is the camplate that operates the plunger, bigger ones give more squirt

Then we have governors & springs, the springs are the bit that are tweakable & react against the Governor

The main rack screw just moves the whole lot further along like giving it more throttle to start with, its only connected to the governor anyways. And the Governor just operates the simplest bleed off valve from the plunger to give throttle variation.

Lastly & this appears to the sneaky one, there is a pressure relief valve for the casing, its normally fixed but they are rather simple to tweak! This is also related to those who have added a booster pump it will have a similar effect to a degree.


The inner workings of a VE Pump revealed, its actually really simple once you get your head round it. Though 160 individual parts simple!

 

[Cptsideways]

Whats inside all the main "bits" less a few shims & washers etc



The input shaft & high volume vane pump to the left, with the gear for the governor & output tang for the next bit



The tang drives the camplate against the roller plate, this operates the plunger (top )



The governor flyweight & lever assembly, top part is the governor spring that is connected to the throttle linkage. The linkage simply operates the sliding ring on the plunger to open a hole in the plunger this sliding ring is actually the throttle!



The hydraulic head is where the squirted fuel is sent round to each injector port, this head has the solenoid that shuts the fuel off.



Told you it was simples

 

[Firewout]

Hi cpt, quite a challenge!
i've been reading a bit on tweaking pumps on mud http://forum.ih8mud.com/threads/the-official-1hd-t-ft-fuel-pump-mod-tuning-thread.728533/
they mention the plunger to be 10 mm on a 1 hz and 12 mm on a hdt
keep posting pls!

 

[Dave2000]

Nice thread, keep up the good work.

regards

Dave

 

[Cptsideways]

The advance system is also quite simple, the roller/cam ring is essentially fixed to body of the pump. But it can rotate 15 degs via a piston at the bottom. Various methods exist for operating it but its just a pressure operated piston, a valve of some sorts bleeds higher pressure off the vane pump into the piston.

Some googling suggests the Yanmar pump is the biggest of them all at 14mm plunger diameter.

I have also learnt there are left & right handed pumps, I have converted a right size but lefty pump to a righty by drilling some new ports for the advance system & blocking the old port as this is the handed part, along with a righty handed advance valve. Swapping the vane pump stator round is simple. The rest is all the same except the head & plunger which are also handed.

 

[Cptsideways]

Can a mod please edit the title should "now know"