Fuel Pressure

[rev-erend]

I have an adjustable fuel pressure requlator and it also has an optional guage.. Great - I love toys

Trouble is - I'm not sure if what it is telling me is a problem or not.

The regulator is fitted (as normal) on the return side of the fuel rail - after the injectors.

The pressure reading at tickover is 39 lbs - I was expecting 43 lbs but it's a small amount and it runs rich as it is..

Now the problem or at least I think it's a problem is when I rev the engine - the pressure drops to 30 ~ 33 lbs and if the revs are stabilised at higher revs the pressure does not return up to 39 ~ 43 lbs.

Do you think this indicates that the pump has seen better days.

Edited by rev-erend on Thursday 18th October 12:07

[gsx600]

I thought you got a small drop when revved, but then pressure would come back up quite quickly,(fuel pump lag?) would check with mine but still awaiting temp sender, but pretty sure that is what mine shows on my fuel pressure guage.

And when I had the fse plumbed in the pressure went up as the revs went up

If you get the 7.2 running sounds like you will need quad pumps

[rev-erend]

gsx600 said:

I thought you got a small drop when revved, but then pressure would come back up quite quickly,(fuel pump lag?) would check with mine but still awaiting temp sender, but pretty sure that is what mine shows on my fuel pressure guage.

And when I had the fse plumbed in the pressure went up as the revs went up

If you get the 7.2 running sounds like you will need quad pumps

THought I asked you to keep quite about the keith Black hemi motor
http://www.keithblack.com/racing_kbblocks.html

[shpub]

Is the regulator plumbed into the inlet manifiold vacuum? If so the pressure is relative to the inlet pressure which often being -ve will result in lower pressures.

[rev-erend]

shpub said:

Is the regulator plumbed into the inlet manifiold vacuum? If so the pressure is relative to the inlet pressure which often being -ve will result in lower pressures.

Steve .. yes it is.

Superb explanation.

I'll try the same test with the pipe clamped.

[gsx600]

[quote=rev-erend
THought I asked you to keep quite about the keith Black hemi motor
http://www.keithblack.com/racing_kbblocks.html
[/quote]

Bet there not cheap

[adam quantrill]

rev-erend said:

shpub said:

Is the regulator plumbed into the inlet manifiold vacuum? If so the pressure is relative to the inlet pressure which often being -ve will result in lower pressures.

Steve .. yes it is.

Superb explanation.

I'll try the same test with the pipe clamped.

.. and disconnect the pipe from the regulator.

Alternatively you could run with Wide Open Throttle ;^) just get a helper to sit in the engine bay and read off the pressure while you accelerate down the road....

[rev-erend]

adam quantrill said:

rev-erend said:

shpub said:

Is the regulator plumbed into the inlet manifiold vacuum? If so the pressure is relative to the inlet pressure which often being -ve will result in lower pressures.

Steve .. yes it is.

Superb explanation.

I'll try the same test with the pipe clamped.

.. and disconnect the pipe from the regulator.
Guess if I don't do this the regulator sees the same as a closed throttle.

Alternatively you could run with Wide Open Throttle ;^) just get a helper to sit in the engine bay and read off the pressure while you accelerate down the road....
That's what girlfriends are for !

[gsx600]

Rev has his bonnet off and in the back garden more often than not, all he needs to do is look through the screen

I of course got round this by taking a feed from the rail (it once fed the cold start inj) on a long length of pipe that sits in the gap between the bonnet and windscreen so I can see guage and drive at the saem time Did the same with the capillary oil pressure guage, just need to remeber which is which

[rev-erend]

gsx600 said:

Rev has his bonnet off and in the back garden more often than not, all he needs to do is look through the screen

I of course got round this by taking a feed from the rail (it once fed the cold start inj) on a long length of pipe that sits in the gap between the bonnet and windscreen so I can see guage and drive at the saem time Did the same with the capillary oil pressure guage, just need to remeber which is which

My bonnet sits neatly on the roof like a giant aerodynamic appendage !

Gives a nice view of the engine too

Edited by rev-erend on Thursday 18th October 16:35

[TVRleigh_BBWR]

Yes I allways take mine off when working on the car, makes it so much easier.
I put mine behind the setee, in the living room tho

And I wonder why I don't have a wife. lol.

[rev-erend]

Your house must have a strange layout ..

[TVRleigh_BBWR]

You don't want to see the amount of car parts currently in my house.
Why must it have a strange layout.

I'm sure in most houses you could fit a bonet behind a setee / couch.

[rev-erend]

I'm just imaging you knocking down the wall to your lounge and driving the wedge in .. keeps it warm in the winter I suppose.

[gsx600]

I was trying for that method as no garage, but Michelle would not let me do it, even when I said we can watch the telly from leather chairs

[rev-erend]

Just accidentally reverse the van in .. job done.

We won't tell her