Fuel pressure regulator-Confused!

Eliot · Post by **Eliot** » Thu Jan 03, 2008 12:29 pm

stevieturbo wrote:Well....I guess the pump could fail. Although TBH, I dont think Ive ever had a Bosch style pump fall apart that badly. Usually they just stop working.

Ideally I guess you would have a filter after the pump. Space is tight.....and I just didnt bother lol.

I dont know what the construction is inside the pump, but if it had bronze bushes - they could be slowly wearing and slowly clogging up your injectors?

kev_the_mole · Post by **kev_the_mole** » Thu Jan 03, 2008 1:31 pm

I didn't have a filter after the high pressure pump because there's not one on the Megasquirt site drawing and I reasoned that if all the fuel was filtered from the lift pump then it would be OK as anything on the swirl pot circuit would be clean. But with the extra information (breakdown of pump bearings etc.) of my new drawing has a high pressure filter after the high pressure pump.

You live and learn especially on this forum

Cheers Guys

Eliot · Post by **Eliot** » Thu Jan 03, 2008 3:22 pm

kev_the_mole wrote:I didn't have a filter after the high pressure pump because there's not one on the Megasquirt site drawing and I reasoned that if all the fuel was filtered from the lift pump then it would be OK as anything on the swirl pot circuit would be clean. But with the extra information (breakdown of pump bearings etc.) of my new drawing has a high pressure filter after the high pressure pump.

You live and learn especially on this forum

Cheers Guys

Where is that shown?

Found this one, which includes the filter:
http://www.megamanual.com/v22manual/minj.htm#supply

stevieturbo · Post by **stevieturbo** » Thu Jan 03, 2008 3:26 pm

Eliot wrote:
stevieturbo wrote:Well....I guess the pump could fail. Although TBH, I dont think Ive ever had a Bosch style pump fall apart that badly. Usually they just stop working.

Ideally I guess you would have a filter after the pump. Space is tight.....and I just didnt bother lol.
I dont know what the construction is inside the pump, but if it had bronze bushes - they could be slowly wearing and slowly clogging up your injectors?

Really, there is actually very little inside.
The one I did take apart, was like mmmm hard to describe. One of those games you put coins into and rotated then they fell out the other end, was the pumping mechanism, which was tiny !!! ( bit solder jammed it, after I soldered a pickup into my mini petrol tank yrs ago )

The rest of the pump is just one big motor !!
I think I have an old one lying about, I might cut it up for a nosey

But I see what your saying.....I guess it is possible. Most injectors have a gauze trap at their intake which should catch big debris. I guess smaller bits might just fly through at full load lol.

winkle · Post by **winkle** » Thu Jan 03, 2008 5:24 pm

OK, filter post pump makes sense as does filter pre pump. Crap from the tank is likely to flow straight into the pump and lunch it anyway otherwise

While we are on this subject, what ID fuel line do people use from tank to pump (or pre filter!) 13,10,8mm. Read somewhere it should be 13mm?

Steve.

kev_the_mole · Post by **kev_the_mole** » Thu Jan 03, 2008 5:25 pm

Where is that shown?

Eliot,

it's on the same page but lower in a section entitled "Surge Tank" which I would guess is American for swirl pot or maybe not. If you reload the page with my drawing on it you will see I have added another filter after the HP pump. Joy of the internet and all that!

Ian

IainB · Post by **IainB** » Thu Jan 03, 2008 6:10 pm

winkle wrote:While we are on this subject, what ID fuel line do people use from tank to pump (or pre filter!) 13,10,8mm. Read somewhere it should be 13mm?

Steve.

Im going to be running a 12AN line from tank to filter to pump then a 10AN feed and return....dont know what that is in MM though - its a tad big though

stevieturbo · Post by **stevieturbo** » Thu Jan 03, 2008 7:38 pm

As big as possible ( sensible ) from tank to pump. This needs to be non-restrictive.

But bare in mind the size of the pump inlet, and length of pipe used to get there.

Bit daft using a 2" hose feeding a 10mm inlet pump.

On the other hand, if it was a 3m long hose only 10mm diam....then of course that could be restrictive.

On the high pressure side, 8mm OD is plenty for most applications ( hardline ) with 10mm leaving ample.

Im using a 1/2" OD hardline tube post-pump with no probs.

I have a single 5/8" feeding both pumps. Not ideal perhaps, but my fuel tank was only constructed with one outlet.
I had no idea where my car was going at that time !!!! lol

blitzracing · Post by **blitzracing** » Fri Jan 04, 2008 1:40 pm

Couple of points in this one. Firstly dont use a rising rate (ie boost type) fuel pressure regulator, it confuses the hell out of the ECU, that allready provides enough fuel enrichment. A bog standard 1:1 regulator will do just fine. Secondly, if you are using Lambda Sensors, the ecu will wind the mixture back to 14.5:1 as far as it can below about 3000 rpm or 3/4 throttle. Above this there is no control so the mixture will change with pressure. If you dont use Lamda probes, the mixture will change throughout the rev range, and can lead to overfueling at low speed. You can compensate somewhat for this by altering the CO adjustment on the air flow meter, but you need a gas analyser to get it correct. The DC voltages stated for setting it will be wrong if the fuel pressure is not standard. If you simply want more power, then a good bet is to use the TVR Chimeara ECU chip, that provides significant gains over the Range Rover fuel map.

Lastly pumps. The failures I have seen are due to bits of fuel tank rust getting caught in the internal rotors (They work a bit like a Wankle engine), so the tolerances are pretty fine.

Its all here:
http://www.g33.co.uk/fuel_injection.htm

Mark

winkle · Post by **winkle** » Fri Jan 04, 2008 9:28 pm

Lot of interesting reading there Mark, thanks for that. Have been on your website before but not the EFI section.

Cheers
Steve