BlueTII

If you don't already know it the PD can blow out in the primary fuel rail causing big problems. I blew my engine at the track last week when the PD decided to fail causing a sudden drop in fuel pressure and instant detonation on the front rotor. Last month a friend blew his engine at the same track, so yesterday when we were installing his new engine we did the routine fuel system leak test and low and behold another PD fuel fountain. Check your PD regularly, if it goes undetected on the street your engine will catch fire, on the track your engine will blow. Just one more thing to add to your routine check list.

BTW we eliminated the PD from the car yesterday by tapping the fuel rail and installing a brass hose barb fitting. $1 vs $130 for new PD.

Elegant Black Monster

Thanks for the heads up. Would you mind explaining the pros and cons of eliminating the PD and perhaps a write up of how you eliminated it. That would be appreciated much.

volley1

Yes, please. If I can understand the pros and cons I may eliminate it also. Thanks.

BlueTII

I will find out the cons today when I fire the engine up. The PD is supposed to smooth out the pulses from the fuel pump making for a smoother idle. I have eliminated it on many FC's and there was no change to the idle.

FC's have the same PD problem but on the S4 there is actually a screw in the end that likes to fall out.

mcf

I have run without a FPD for about 15K miles without any noticeable change in operation, at any RPM range. So far, a good reliability modification.

YayeR

urmm what does it look like?

chris im saving up for a big project, ill tell you about it next time im at your shop (which should be soon, i still havent wired the guages and I've had this brand new fuel filter sitting in my garage for a months and I was hoping you could help me put it in) so you can tell me how stupid I am and why it won't work.

pomanferrari

iTrader: (1)

The Pulsation Damper is used to dampen pulsation hammering back and forth in the lines and the injector.

Without the damper, the pulses would cause the injector pintle to hammer back and forth against the valve seat during closing. At least that's what the Siemens injector people explained to me.

Mazda tried to take off weights by drilling out the pedals, using hollow fiber carpet. Do you think Mazda put the FPD just so the car is less reliable and heavier by about 8 ounces? They put it on for a reason. Take it off at your own risk, just like the AST.

CCarlisi

According to SX their aftermarket regulator operates as a pulsation damper. I posted the response of their engineering department in the thread below. I don't see how having a combo pulsation damper/regulator located downstream from the secondary rail will dampen the static created by the primary injectors cycling. However, a lot of people have done this without a problem.

https://www.rx7club.com/forum/showth...ion+damper+FPR

mcf

I agree. Madza put everything on the car for a reason, so caution should be made on ANY change you make to your car. If my injectors fail you can bet I'll report it back.

AMRAAM4

I'd be interested in knowing just how you regularly check this??? Are we suppsoe to rip off the TB/UIM/sol. rack on a regular basis?

DCrosby

From what I understand the FPD should go on normal street wear and tear.. every 50-60K....
Kind of like a timing belt (What's that?) so for the track I'd say half or quarter that to be sure.... Also (Previous discussion on this do a search) the FPD is made out of rubber and steel, and the FTBE found in a lot of gasoline in California (Other than 76) will slowly eat up rubber and cause your FPD to possibly go sooner, although I've spoken to some that say without FTBE the FPD should last a heck of a lot longer since it's the rubber / heat and FTBE that cuses it to leak... take one of those away and you might see a 30% longer life... who knows...

-DC

jantore

Where do i find this PD?

BlueTII

OK results were a flawless 750 rpm idle and no chance of the PD developing a leak and causing an engine fire.

AMRAAM - If you have have to, removing the UIM is not a very difficult task

All you have to do is put a jumper in your fuel pump connection and turn the key forward to see if it is leaking

SilverRX7

I love how overnight mechanics think they are smarter than OEM Mazda engineers and assume a part has negligable affects and therefore remove it... this is why these people blow engines.

Cetchup

Whoa. Sensing some hostility? I'm sure BlueTII dosn't think he is any "smarter" than Mazda engineers. He saw a problem with a part that those rocket scientists at Mazda developed and has thought up a way to maybe fix it. He never told anyone to 100% run out and do this. Just sharing his experience.

saxyman990

He also is not an "overnight mechanic." This guy has forgotten more things about RX-7's than you'll ever dream of knowing...

Besides, if all people were to use your logic, no one would ever change intakes, or exhaust, or ast's, or radiators, or get rid of that damn pre-cat....

cpa7man

iTrader: (2)

I think Silverrx7 needs to re-think his post. Mazda has made some awesome cars, and has also make some mistakes as well.

Thanks for the heads up bluetII.

bureau_c

That is an excellent point. On that note I think I will go out and put my old stock plastic AST back on the car. Oh wait, I'd better glue it back together first.

jds

InsaneGideon

I was running an 8psi blower in a miata with a stock fuel pump. At max boost (and max pressure from the aftermarket AFPR) the car would surge wildly. I hooked up an analog fuel press. meter directly to the send line near the rail and clamped off the return line. This was in effort to find max no-flow pressure of the pump. I was treated to a wild fuel press. fluctuation on the order of 40 psi, peak to peak. The damned gauge was about to vibrate out of my hand. A year earlier, with the exact same setup, no problems at all. Replacing the pump with a fresh one cured it.

I can see how a worn fuel pump can be more succeptable to pressure damping. So perhaps the PD is there for the case of an old or nearly-out-of-spec FP.

neptuneRX

No doubt the mazda engineers put things into the car with good intentions, I believe that 100%, but theory goes out the window when your car in burting in flames.

EpitrochoidMan

'OEM engineers put everything there for a reason and they knew what they were doing' I agree with that, to a point. But, engineers never work on cars, and not everything they put into cars is right. Don't believe me? Look at any ford vehicle.

Jonesboro

There's no need for an arguement here. Replace the FPD or eliminate it, that's your choice!

This thread by BlueTII is doing the right thing by reminding everyone that after 10 years of service the original Fuel Pulsation Damper on FDs have started failing and when they fail the result is often a costly engine fire.

If you choose to replace the FPD you should be good to go for another 10 years.

wonder1and

I have a FPD for sale if anyone needs one... only has 200 miles or so on it... then went single...
Thanks,
Ryker