jjcobm

iTrader: (18)

Hello,

I have an s5 vert that at the moment has a leaking pulsation dampner. I have been reading a few threads on this specifically this one:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/can-someone-direct-me-611176/

My PD is currently leaking at the end out of the famous small rubber plug. Would it be safe to have somebody weld that end shut so my fuel stops leaking?

RotaryResurrection mentions that it is possible to do this, but I haven't been able to find any information elsewhere about this. Seems like everyone documents their leaks on s4's more than s5's.

Is there any downside to sealing the end of the PD shut? Will it cause any harm in the future?

Right now I wish I had an s4 fuel rail, to everyone saying the s5's are more reliable, the design of the s5 is a pain in the butt because you have to replace the whole rail instead of the single PD, plus the s5 has this rubble plug that is leaking, A RUBBER PLUG!? Why???

Thanks for the help on this.

arghx

iTrader: (3)

here is a PD elimination writeup for the FD which may give you some ideas:

http://www.banzai-racing.com/pd_elimination_how-to.htm

jjcobm

iTrader: (18)

The way the PD is on my s5, i don't believe the method for the fd will work here, but i appreciate you posting that up.

I could see this working if I completely cut off my PD and weld the end shut, then add a fitting like they did in that link. Unfortunetly I am just looking at sealing that leak at the end of the PD where the rubber plug is.

Would anyone know if I seal it like i mentioned above (weld), would that cause it to still "loose pressure" somehow and maybe run my engine a bit lean or will this complete fix my problem?

I am thinking if this can be done it will be like a permanent fix since the plug will not be leaking ever again or am i wrong?

jjwalker

Replace the fuel rail man.

Welding it would fix the issue, but on the same note, the PD is there for a reason. The fuel rail experiences a water hammer effect when the injectors close.

See this...

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

harley71105

The only thing in a PD is a rubber diaphragm that acts as sort of a shock absorber)....what I did was get the identical parts off a salvage rx and switched the connections around (you can figure it out when you get all the parts together) and just used an extra 9" of hose from where the PD was to the fuel inlet....I used some rubber insulators around the hose where it comes into contact with other engine parts to prevent compromising the fuel line and this extra "loose" hose acts as much as a shock absorber (in my opinion) as a PD and you don't have to worry about having to remove the upper Intake system to replace it....been running it two years with NO Problems

jjcobm

iTrader: (18)

Well as far as the welding goes, I won't be completely removing the PD. I am just debating on sealing the tiny little rubber plug at the end of it where it is leaking. So in fact, i will still have the PD, but just sealing my leak with a small weld (im thinking having someone TIG it).

If the PD is just a rubber diaphram, I guess sealing the small leak at the end of it will do no harm. I'm thinking of going ahead with my plan unless anyone can point out a good reason not to go this route?

Keep in mind this is on an s5 with the fuel rail/PD all in one unit that is "closed off" with a rubber plug.

I'll keep checking this out to see what everyone thinks.

I appreciate all the replys!

jjcobm

iTrader: (18)

If you look at the arrow, right in the middle of the PD (if you were to rotate this picture 90 degrees counter clock wise) is the rubber plug that is leaking which i am debating of sealing right now.

jjcobm

iTrader: (18)

sorry, here is the one with the arrow

jjwalker

The problem is this...

If you weld that hole shut, yes it will stop leaking, but it will also trap fuel behind the rubber diaphram. Regardless if the leak is small or big, the back side of the diaphram will fill with fuel. The diaphram isn't the cushion, it is just a seal. The atmosphere BEHIND the diaphram is the cushion. If the backside of the diaphram is sealed, and fills with fuel, there is no more cushion because the laws of physics state that fluids cannot be compressed. At this point, it may as well be solid.

Now before someone brings it up, no, the air will not be trapped behind the diaphram forever because it has nowhere to go after the case is welded. The air will either dissolve into the fuel over time or find its way out through the injector. When the car is shut off and fuel pressure is gone, if it is a small leak, the fuel will stay trapped on the other side of the diaphram where it isn't supposed to be.

Rx7TyreBurna

iTrader: (1)

I know there are some aftermarket FPR's that have PD's built in.

Welding sounds like a bad idea. I think the screw in the end is actually attatched to the rubber diaphram inside. Not 100% sure though. I remember trying to figure a way to fix it when mine broke. Ended up going FPR w/ PD built in.

RotaryRocket88

iTrader: (7)

Just buy a new rail. Post in the classified section, and I'm sure someone will have one available.

Welding fuel components is not the safest thing to do. You would want to leave the rail sitting out for days to allow all of the fuel to evaporate away. If even a small amount of fuel vapor is trapped between the rubber and the diaphram wall, it could ignite when arc is applied.

jjcobm

iTrader: (18)

Makes sense what you guys are telling me. I think I am going to look into an aftermarket pressure regulator/dampner setup, i don't want to deal with this thing anymore. If anyone knows of a good set up let me know, i'll be searching for some info.

Thanks again.

vato2000taco

iTrader: (1)

just cut it off after all it is a dampner not a fuel pulsation eliminator it only dampens the pulsation even if u get a fpr wid pd built in u still got a leaky stock fpd . i removed mine completely two years ago and mine runs fine

jjwalker

Bad advice. Don't **** with your fuel system (or the engineering) unless you plan on making it more reliable. Mazda put it there for a reason. Don't worry, they used every cost cutting measure possible in engineering your ride.

I won't say I don't do stop gap fixes, as sometimes I don't have the cash (see my outer coolant seal thread) but there is a point where you need to pony out the cash and get it fixed right.

Rx7TyreBurna

iTrader: (1)

I'm curious to know if an external FPR w/ PD built in would be just as good as the stock setup. I currently run an external FPR w/ PD. I haven't seen any problems at all.

jjwalker

As long as there is something to dampen the pulses from the injectors closing, then you should be golden.

hypestar1983

this wont help you as it is for an s4 but this statement might make people a little quiet about the deletion thing and give you an idea about what to do. I put a banjo bolt on my rail and a fuel pressure sending unit in place of the pulsation damper. I have a steady flow on my guage of 38 psi at idle and deceleration and 44 psi under acceleration. both values stay constant and do not fluctuate. i'm not gonna tell anyone what that says about deleting a fpd but for someone to say mazda put it there for a reason should 1) give proof, and 2) already know that mazda put a cold start system on an rx-7 only to say 'remove it' later. Now i'm just giving facts, and have not told any opinions so i dont want anyone telling me i'm wrong or giving me a pat on the back for putting this out there. I'm just saying.......

SecondGenPat

As far as i can find from any mazda or toyota information, the main reason the pulsation damper was installed is to silence the noise of the fuel rail, pump, and the sounds of the injectors when operating.
The older v6 camry's have almost the exact same pulsation damper as the s4's do. Runs $95 from a dealer. (cheaper if you work at a toyota dealership )
I did the banjo bolt damper delete, no problems with oem driveablilty

SecondGenPat

oh and jjcobm,
I did exactly what you are thinking about with a friends s5 rail, no problems in a year. I used a MIG welder because it was what i had available. a TIG should work just as well. Just have a professional do it.
-Pat

hypestar1983

as an ex 86driver i have to say that far more supra owners have done this than us and are quicker to delete the fpd because of the same malfunction and the fact that more people have used the banjo bolt trick and yeilded no side effects even in the boosted supras that see well over 550 horse power.

jjcobm

iTrader: (18)

Well just to update, I found a PD on the classifieds for a good deal. Now my car is running happy with it and new vacuum hoses. I will definetly be going the TIG route if this beast ever leaks on me again. I went as far a wrapping the guy with heat wrap just so those engine temps dont deteriorate it (not sure if its true), but thats how paranoid I am. This is all assuming I still have my NA engine by the time it leaks.

I rather be safe knowing that I don't have to worry about an engine fire with a TIG welded PD or after marker FPR than to drive one day and smell fuel like I did ($220 dollard for a new PD? WHAT?). If you do TIG it, you still have the diaphram in there so in theory wouldn't it still absorb the shock? A leaking PD is not a funny experience.

Thanks for all the feedback once again.