Hey guys i have noticed this odd fluctation the last two days with my fuel pressure. What I am seeing is my pressure go from 16-18 psi then it usually starts to fall off when i am slowing down to stop, i will see anywhere from 2 to 5 to 7 to 10 psi with absoutely no engine indication that this is actually happening!!! (i think maybe false indication???) my fuel pressure has always been very steady until last night and today. :banghead:

[ATTACH=CONFIG]2259[/ATTACH] http://www.vulcanperformance.com/Push-Lock-Fuel-Pressure-Tee-1-2-p/plt8.htm Ok cool thank, this is the one that I am running about 6 inches or so from the VP44. But since we are on the subject what is the size of that needle valve and how far from the sender should it be installed?

Mine is a 1/8" NPT need valve installed in that exact fitting above... But there is a problem electric sender don't work unless you give then a ground. That the problem I got currently with my exist low pressure switch that was I suggest the fitting above. Now since the Water Hammer source is at the VP44 it highly suggested to mount your fuel pressure gauge as far from the source of the water hammer. Less damage that way. But remember the fuel pressure sender must be after the filter... So if your like me you have a stock fuel filter housing that typically will have a air bubble on top which acts as a shock absorber so if you tap the line just after the filter housing it will aid in suspressing the water hammer effect.

so your needle valve is installed in this fitting??? and your fuel sender is back at the pump???

so your needle valve is installed in this fitting??? and your fuel sender is back at the pump???

Not sure if I follow what you're asking but you install the needle valve into the fitting and the sender onto the needle valve. Or run a grease gun hose from the needle valve and put your sender on the end of that to further dampen the water hammer.

wow ok i think i have this pictured in my head but just to clarify i would install the needle valve into the fitting and on the other side of the needle valve i would install my fuel sender??? if this is not correct does anyone have a pic of there setup???

wow ok i think i have this pictured in my head but just to clarify i would install the needle valve into the fitting and on the other side of the needle valve i would install my fuel sender??? if this is not correct does anyone have a pic of there setup???

I think there is a pic floating around but maybe you can understand it if you work it out mentally. We know the fuel pressure hammer is what we don't want. We know the needle valve will stop it. So you would have your line running from the fuel system (which is hammering from the lift pump), then you would eliminate the hammer with the needle valve, then you would put the fuel sender on after the needle valve since it MUST NOT SEE THE HAMMER, so it goes AFTER the needle valve has eliminated it. It eliminates it by reducing the flow to the point that the bursts of pressure (the hammer) can not flow through the needle valve because the flow is almost next to nothing, so you get these positive spikes of pressure followed by a void, so you get a little pressure from the pressure spike and a void of pressure in between the pumping actions of the lift pump which gives you a fuel pressure that is basically the average of the void and the spike, because that is basically what the fuel system also sees. Now that you understand what you are trying to eliminate with the hammering effect and how everything works, you probably understand how to do it. If not, someone will have a pic or I will dig one up.

wow ok i think i have this pictured in my head but just to clarify i would install the needle valve into the fitting and on the other side of the needle valve i would install my fuel sender??? if this is not correct does anyone have a pic of there setup???

Here is a older setup...

Now what does a single water hamer pulse look like???

More about water hammer...

http://en.wikipedia.org/wiki/Water_hammer

I think there is a pic floating around but maybe you can understand it if you work it out mentally. We know the fuel pressure hammer is what we don't want. We know the needle valve will stop it. So you would have your line running from the fuel system (which is hammering from the lift pump), then you would eliminate the hammer with the needle valve, then you would put the fuel sender on after the needle valve since it MUST NOT SEE THE HAMMER, so it goes AFTER the needle valve has eliminated it. It eliminates it by reducing the flow to the point that the bursts of pressure (the hammer) can not flow through the needle valve because the flow is almost next to nothing, so you get these positive spikes of pressure followed by a void, so you get a little pressure from the pressure spike and a void of pressure in between the pumping actions of the lift pump which gives you a fuel pressure that is basically the average of the void and the spike, because that is basically what the fuel system also sees.

Now that you understand what you are trying to eliminate with the hammering effect and how everything works, you probably understand how to do it. If not, someone will have a pic or I will dig one up.

thats what i had pictured in my head. thanks ISX. i guess somewhere in the midst of this thread i got a little turned around:shrug: but all is good now:lol:

--- Update to the previous post...

Here is a older setup...

Now what does a single water hamer pulse look like???

More about water hammer...

http://en.wikipedia.org/wiki/Water_hammer

Mike thank you for the pic, now i just have to find one a place in little southeast kansas where i can get one of those since we dont have a NAPA hear!!!

It's a Weatherhead Part (WH6820) you should be able to get it through any part store selling hydraulic hoses and such... But here is the part page from Napa for you...

Water hammer is like jumping on your bathroom scale a million times.. You can average out the bouncing and might get your weight but it will break the scale in no time. This doesn't matter if it is a mechanical or electric sender, they both cannot take the hammering.

Water hammer is like jumping on your bathroom scale a million times.. You can average out the bouncing and might get your weight but it will break the scale in no time. This doesn't matter if it is a mechanical or electric sender, they both cannot take the hammering.

thats an excellent example:smart:

--- Update to the previous post...

It's a Weatherhead Part (WH6820) you should be able to get it through any part store selling hydraulic hoses and such...

But here is the part page from Napa for you...

[ATTACH=CONFIG]2270[/ATTACH]

You are awesome man!!!

closest napa is in neodesha "D":thumb1:

closest napa is in neodesha "D":thumb1:

Ah ha the only other one that i knew of was in fredonia!!! thanks White

ok so before i install a needle valve i have to ask the question does this not cut off flow to the injection pump??? this is a restriction in the system correct??? and what does a snubber line install consist of/look like???

Your "snubbing" the supply line to the psi sender or gauge, which is T'd off the main line, so flow to the pump is not effected.

do you happen to have a pic of a snubber install?

do you happen to have a pic of a snubber install?

Just replace the needle valve with...

As you can see a needle valve is adjustable and can be shut off where a fuel pressure snubber is a fixed offrice and never be adjusted nor shut off...

At rate the snubber or needle valve should always be installed at the source... Not at the gauge...

Just replace the needle valve with...

As you can see a needle valve is adjustable and can be shut off where a fuel pressure snubber is a fixed offrice and never be adjusted nor shut off...

At rate the snubber or needle valve should always be installed at the source... Not at the gauge...

so i install the snubber into my existing fuel pressure tee and then the fuel sender/sensor into the snubber correct??? do you happen to have a part number for the above pic, or would i just find it at jegs, summit, etc???

http://www.summitracing.com/parts/ATM-3279/

found it not too bad of a price only 18 bucks!!!

Fuel Line Tee -> Snubber/Needle Vavle -> Sender/Gauge

got it thank you for your patience and time Mopar!!!

got it thank you for your patience and time Mopar!!!

That's what its all about is having the patience to show/explain to the members how things are done... More than welcome...