In the BIG nissan book it says at the FPR is should be 43.4 psi

 

But reading back on other threads they say its lower?

 

So what should the pressure read on idle?

In the BIG nissan book it says at the FPR is should be 43.4 psi

 

But reading back on other threads they say its lower?

 

So what should the pressure read on idle?

 

Hi Mate,

 

It should read 43.3psi with the vac line disconnected from the FPR.

 

When the vac line is connected the regulator drops the pressure down on idle.

 

If your idle is fast or slow this will effect the pressure via the FPR with the vac line connected.

 

Therefore if you want to see how you FPR is performing, disconnect the vac line and see what the pressure is.

 

Cheers

 

Andy

Yeh i thought that but this is what the big book says

 

"The pressure regulator maintains the fuel pressure at 299.1 k (2.991 bar, 3.05 kg/cm3, 43.4 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain he pressure at the above value."

 

you would have thought it would have given a different reading at idle if its not 43.4psi?

Yeh i thought that but this is what the big book says

 

"The pressure regulator maintains the fuel pressure at 299.1 k (2.991 bar, 3.05 kg/cm3, 43.4 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain he pressure at the above value."

 

you would have thought it would have given a different reading at idle if its not 43.4psi?

 

The thing is you need a constant.

 

The FPR regulates fuel pressure against crank case vacuum which is influenced by engine speed. So, for some reason if your engine speed is high lets say cold air temp or cold engine, the FPR will show a different reading.

 

If you like it's like putting the FPR in neutral and getting its default setting while not being influenced by anything.

 

That's the only way I can explain it bud.

 

Andy

The thing is you need a constant.

 

The FPR regulates fuel pressure against crank case vacuum which is influenced by engine speed. So, for some reason if your engine speed is high lets say cold air temp or cold engine, the FPR will show a different reading.

 

If you like it's like putting the FPR in neutral and getting its default setting while not being influenced by anything.

 

That's the only way I can explain it bud.

 

Andy

 

I understand bud, i was just thinking wouldnt it have been easier for nissan to put in the big book that at idle the pressure at the FPR is = A

 

As most people will check the pressure at idle when the vehicle is stationary

Around 37 psi at idle.

Around 37 psi at idle.

 

cheers jimmer, i suppose what i meant was couldnt nissan have just said its 37.78 psi on idle at the fpr? you know what i mean something exact? or am i being an ass :rofl:

No i agree Mike.You never quite get the exact bit of info thats more relative to your particular problem.Drives you nuts dont it :rofl:

I understand bud, i was just thinking wouldnt it have been easier for nissan to put in the big book that at idle the pressure at the FPR is = A

 

As most people will check the pressure at idle when the vehicle is stationary

 

Can't comment on the big book mate as i have never seen it. Maybe it's a translation issue?

 

Where are you getting your reading from?

 

Andy

Can't comment on the big book mate as i have never seen it. Maybe it's a translation issue?

 

Where are you getting your reading from?

 

Andy

 

"The pressure regulator maintains the fuel pressure at 299.1 k (2.991 bar, 3.05 kg/cm3, 43.4 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain he pressure at the above value."

 

thats what the official nissan service manual says the pressure is LOL

 

clear as mud

Hi Mate,

 

It should read 43.3psi with the vac line disconnected from the FPR.

 

When the vac line is connected the regulator drops the pressure down on idle.

 

If your idle is fast or slow this will effect the pressure via the FPR with the vac line connected.

 

Therefore if you want to see how you FPR is performing, disconnect the vac line and see what the pressure is.

 

Cheers

 

Andy

 

Slight boo boo - the fuel pressure goes up when you reconnect the vac line, not down.

 

No more beer for me!!!!!!!!:rofl::rofl:

i knew what you meant LOL

"The pressure regulator maintains the fuel pressure at 299.1 k (2.991 bar, 3.05 kg/cm3, 43.4 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain he pressure at the above value."

 

thats what the official nissan service manual says the pressure is LOL

 

clear as mud

 

No, what I mean is - are you using a fuel pressure gauge in the cock pit?

 

 

Andy

No, what I mean is - are you using a fuel pressure gauge in the cock pit?

 

 

Andy

 

No, its part of the FPR in the engine bay bud

I wonder sometimes if back in the day even nissan couldnt fully explain their creation.Some of its technology was incredible when you think it was released around 1989 so would have been on the drawing board years before when cars were running very crude fuel injection systems etc.

I wonder sometimes if back in the day even nissan couldnt fully explain their creation.Some of its technology was incredible when you think it was released around 1989 so would have been on the drawing board years before when cars were running very crude fuel injection systems etc.

 

must admit when i read the specs its so over engineered its silly but as you said it was miles ahead of its time

Slight boo boo - the fuel pressure goes up when you reconnect the vac line, not down.

 

No more beer for me!!!!!!!!:rofl::rofl:

 

Oh FFS!! No, I was right in the first place!!!!

 

I'm having another beer!!!!!!:duffer::duffer::duffer:

Oh FFS!! No, I was right in the first place!!!!

 

I'm having another beer!!!!!!:duffer::duffer::duffer:

 

your confusing me now :D have a chaser with you next beer bud :p

No, its part of the FPR in the engine bay bud

 

Which one have you fitted?

 

Andy

Which one have you fitted?

 

Andy

 

its a mines copy i think but works well and its decent made

 

looks like this one

its a mines copy i think but works well and its decent made

 

looks like this one

 

Nice!!

 

Mine looks like this.

 

 

BTW that picture is with the ignition on and no vac pressure hence the reading of 43psi!!!

 

 

Andy

is that the aeromotive one? very nice, i got mine cheap as i wanted one with a gauge because the previous owner had a few pressure issues so wanted to check the pressure is stable :)

is that the aeromotive one? very nice, i got mine cheap as i wanted one with a gauge because the previous owner had a few pressure issues so wanted to check the pressure is stable :)

 

It's an Aeromotive copy but don't tell anyone!!!

 

Andy

It's an Aeromotive copy but don't tell anyone!!!

 

Andy

 

looks nice, where did you get it from bud?

Ladies,ladies make yer minds up FFS LOL. I set my fuel pressure reg "SARD" with vac connected at 42 1/2 PSI. So should I now set with vac off at 37 ish ? I have a gauge on both lines.

If I do it that way how will I know when off idle it reads 42/1/2 PSI