fuel pressure gauge

[Cambridge_pulsar]

I recently bought an in-line fuel pressure gauge to test my fuel pressure but it doesn't record the maximum pressure. This is ok for testing it on idle but I need to know what it is at full boost. In my eyes this makes it completely useless or am I missing something...?

 

[youngsyp]

When you say it won't record maximum pressure, what do you mean mate ? 'Maximum pressure' for what ? What is 'maximum pressure' ? Etc...

As for fuel pressure at full boost, it should be whatever your fuel pressure at idle is (should be 3 bar with the vacuum hose disconnected), plus your peak boost level. So, if you're running 1 bar at peak boost level, your fuel pressure should read 4 bar at full boost !

Paul

 

[Cambridge_pulsar]

I know I can calculate what the max pressure should be, as you describe, but if the pressure gauge doesn't record the max fuel pressure reached how can I check it? I'm assuming that revving the tits off it from under the bonnet won't be enough, it needs to be driven on the road.

 

[gtirjoey]

either employ a lepricorn to sit under the bonnet while you drive down the road! lol
or run a TEMPOERY line inside the car to check it.
Is your car running funny then? if not i would not worry to much!

 

[Cambridge_pulsar]

either employ a lepricorn to sit under the bonnet while you drive down the road! lol
or run a TEMPOERY line inside the car to check it.
Is your car running funny then? if not i would not worry to much!

Yeah I did think of that but if the item is fit for it's purpose that wouldn't be necessary. Yeah it's not quite at it's best and I wan't to be sure the fuel pump isn't the culprit.

 

[gtirjoey]

oh write so is it ment to store the max fuel pres?. surely this would not tell you much anyway as the the pump could be supplying pressure when the car is off boost but as the car comes on boost the pump would then not be able to supply pressure so the gauge would jus store the maximum pressure before it came on boost and lost pressure? i would of thought you need to be looking at the gauge as the car is on boost but i could be wrong

 

[Cambridge_pulsar]

Yeah that's kinda my point, i'm trying to check that at full boost the fuel pump is supplying enough fuel, e.g. base pressure + boost pressure. As you can't watch the gauge as you are driving if it doesn't record the max pressure how can you check, if you can't then to me it's useless. I was under the impression that this was a simple and common thing to check. Surely someone has done this before... lol

 

[youngsyp]

Yeah that's kinda my point, i'm trying to check that at full boost the fuel pump is supplying enough fuel, e.g. base pressure + boost pressure. As you can't watch the gauge as you are driving if it doesn't record the max pressure how can you check, if you can't then to me it's useless. I was under the impression that this was a simple and common thing to check. Surely someone has done this before... lol

Sorry, you've not made it clear... Did you buy an electric gauge with record and playback function ? Or, just a 'normal' mechanical fuel pressure gauge ?

Paul

 

[GTi-R23]

Get it on the rollers.

 

[Cambridge_pulsar]

Sorry, you've not made it clear... Did you buy an electric gauge with record and playback function ? Or, just a 'normal' mechanical fuel pressure gauge ?

Paul

Just an in-line mechanical one, I assumed it could be used to measure max fuel pressure under heavy load, all i'm trying to confirm is that the fuel pump is capable of supplying enough fuel for my current set up. I know I could get it on the rollers but I assumed this would work. :-D

 

[ashills]

nah they dont do a peak hold they are far to basic lol

what pump is it and what boost u running etc if its a walbro they have grief when run at 4 bar base pressure but at 3 bar will supply enough fuel for 500

 

[MarkTurbo]

What you need is a defi fuel pressure gauge. It uses a separate sender unit so you can mount it in the car safely and as well as recording peak pressure if you've got the boost gauge too you can monitor pressure differential which will tell you if the fuel pressure is rising at the same rate as the boost pressure ;-)

 

[youngsyp]

Just an in-line mechanical one, I assumed it could be used to measure max fuel pressure under heavy load, all i'm trying to confirm is that the fuel pump is capable of supplying enough fuel for my current set up. I know I could get it on the rollers but I assumed this would work. :-D

As Ashills has said, a basic fuel pressure gauge will not do peak hold. It will just show a real time measurment !

If you want to see it working inside the car, just run some longer fuel lines and attache it to your bonnet...

Paul

 

[GTi-R23]

It's the kind of thing you only really need to set once, ie when mapping a car to a new set-up, hence why it doesn't have a peak hold value as they're meant to be used on a RR or as said above as a temporary measure run lines into the car if you're setting it up on the road.
There are easier ways to simply check if your fuel pump is up to scratch or not.

 

[Cambridge_pulsar]

There are easier ways to simply check if your fuel pump is up to scratch or not.

Do tell...?
I have a walbro uprated pump, which has been re-wired.
Incidentally my base fuel pressure was: 3.4bar without vac, and 3.1bar with vac attatched. :-D