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Tuning fuel pressure regulator
Posted: Thu Jun 29, 2006 1:15 pm
by johnhup
As many of you will be able to tell from this post, I am new to fuel injection. I have collected almost all of the necessary parts and getting ready for installation. My final question is how do I know what my fuel pressure regulator is set at?
I have seen many different types of pressure gauges but I am just not sure which one to get and how to use it exactly. My thought would be that I would have to measure the pressure right before the regulator with some type of T adapter?
Can anyone help clarify my situation?
Posted: Thu Jun 29, 2006 2:47 pm
by woh
Here is a link to some pressure gauges.
http://www.davis.com/showpage.asp?L3ID=1275
You will have to provide a T or some other means to connect the pressure gauge between the fuel pump and the fuel regulator.
Posted: Thu Jun 29, 2006 4:41 pm
by Minami Kotaro
You can get a cheap, 0-100 psi gauge with 1/8 NPT threads at almost any store that sells air tools and/or compressors. Setting up a T or some other means of plumbing it into your fuel system shouldn't be hard.
I'm lucky in that my fuel rails have 1/8 NPT ports on them already.
Posted: Tue Jul 04, 2006 3:45 pm
by MattKab
I also am a newb loosing sleep over fuel pressure

Waiting for the penny to drop.
I'm closing in on running my T4 Beetle engine, it will happen this summer.
I have everything looking good on MT with Extra on my 4 legged, round, Pine wood kitchen table. I am pleased how smooth it runs!
How does MS deal with fuel pressure? I sort of understand the response of a MAP referencing FPR, I'm confused about why MS doesn't need to know a base FP.
I have stuff (Innovate Logworks2) to map and plot the characteristics of my FPR's, I just need to know if over-pressure will kill a 3bar Cosworth type MAP sensor for logging fuel pressure. I don't know if that's absolute pressure, which I expect it maybe from ebay..

They are ~£60 new on ebay, plenty too! I'm tempted..
Any tips on getting 0-~60psi to 0-5v would be timely

and why does MS ignore fuel pressure?
Matt
That makes sense
Posted: Thu Jul 06, 2006 12:46 pm
by johnhup
Now my last question is, can I keep the pressure gauge on there permanently? Can it take all the vibration or should I plug up the hole when I am not using it? I would like to leave it on their permanently if possible.
Thanks.
Posted: Fri Jul 07, 2006 4:57 am
by Mk1rocco
A cheap pressure gauge will eventually fail, in high vibration applications, I've seen the needle drop off of more than one gauge. If you want a permanently mounted gauge, isolate it from the engine vibration with a short run of flexible tubing like you would with an oil pressure gauge (but, don't mount it in the cockpit) or else spent a few more bucks and get a better quality gauge that can withstand the vibrations.
Posted: Fri Jul 07, 2006 5:34 pm
by jakobsladderz
If your pressure regulator is not manifold referenced then you'll need to get one that is because it makes tuning the engine a lot easier. it takes one variable out of the system.
There is an entry in MS/MSII for base fuel pressure...indirectly. it's in the required fuel value - how much fuel the injector flows. because of the manifold reference the injector flows at the same rate regardless of the manifold vacuum, making the flow rate depend only the injector characteristics and the base fuel pressure. The actual value of the base fuel pressure is not relevant (so long as it's high enough for atomisation and low enough for the fuel pump and injectors to work properly) so long as the car is tuned with that setting and it is not changed.