86-88 Pulsation Damper / Banjo Bolt
 

Hi peoples,

I recently pulled out my faulty Pulsation Damper (86'), screw backed out into plastic cap and discovered a slow leak.

Now before I replace this unit, I was wondering if anybody has completely removed this unit with a regular banjo bolt? I heard it could be done but was wondering about the performance at idle, low end and top end. My friend was saying that it would probably be noticeable at higher RPM's (stronger pulse).

If anybody has done this conversion please let me now about any noticeable differences. I would like to solve this problem once so I can move on and fix the rest of the car. (was flooded when i noticed the fuel leak so before i try unflooding it i want to do this preventive maintenance).

Maybe I should switch to a 89-up fuel rail/damper but I hear the unit fails with time regardless. Also harder to replace.

THX

There are many people who have replaced it with a banjo bolt with seemingly no ill effects. HOWEVER, I am from the school that says Mazda put it there for a reason, and therefore I suggest installing the '89 fuel rail/damper. They are much less failure prone then the '86 style.

i have an 88TII and i replaced the PD with a banjo bolt, and my car is fast as shit....
i havent noticed any ill side effects directly relating to that...
my idles kinda goofy, but its cold here and i took out the cold start, amongst other things....i say do it.....if you dont you will just keep replacing the PD's and they get expensive...the banjo bolt cost me less than $20 shipped....
ive HEARD, that the series 5 fuel rail is more reliable, but still fails...and if it does your still gonna have a fried engine....since i have done it with no ill effects, as have alot of the "guru's" on this forum, GO FOR IT....
=-dustin

Do I just get a generic banjo bolt that will fit in the rail, or do I need a special one? If it's special, where can I get the banjo bolt?

Thanks,
Glen

Summitracinge.com They have it but I don't have the EARLs part # sorry.

Thanks! :bigthumb:

If you are going to replace the PD with a Banjo bolt, make sure you replace your soft fuel lines under the hood as well.

Running without the PD is hell hard on the fuel lines and makes the lines act as the PD, rather than taking up the slack that a PD would normally do.

On 15 year old fuel lines, this makes them very prone to leaking or cracking.

I agree with Aaron, it is micky mouse to replace the PD with a bolt, but I disagree that the S5 rail is a solution. I personally have seen more S5 PD/rails leak than S4 PDs.

I replaced mine with a 90deg. hose fitting, effectivly the same as a banjo bolt. No ill effects here at all, I also replaced all my fuel lines at the same time.

Just make sure you remember the copper crush washers, they very important in stopping fuel leaking, just ask me how I know ;)

good advice, I'm leaning towards installing the banjo bolt. I'll also check my fuel lines. Is there any inline device to relieve the pressure from the fuel lines?

12mm x 1.25 banjo bolt
earls part no. 997591
Summit Part no. EAR-997591

http://fc3s-pro.com/TECH/FAQ/pd.htm

yeah, for while the car is running, its called a Pulsation damper.

For flooding issues when your injectors lock up, there is a device at Mazdatrix/raceing beat.

unplug the fuel pump plug in the hatch area under the carpet while the car is running, that'll use up the pressurized fuel in the system :bigthumb:

I think the pulsation damper is a crock of shit. modern fuel pumps don't puls like the ones driven mechanicly off motoer power. These old timers generally move a large diafram with either a lever or cog. The electric ones move a smaller diafram faster, and more accuratly. the pulses would be less intense and more frequent then in the old days when they didn't even use a PD on 4 bbl carbs and other crap. they still don't on 5000 horse funny cars.
Mazda put it there because the guy that engineered the fuel system though it would be a good idea "just incase" and they had nothing but trouble. I bet he doesn't work there anymore.
Just do it. I am going to.

You don't understand what the PD does.

The PD isn't for the fuel pump it's for the shockwave from the injectors closing.

They don't need a PD on a carb'd car because there is no fuel rail or feul injectors shutting off the flow of fuel.

The concept is even used in houses. Ever hear a clunk when your toilet stops filling or you turn a sink faucet off fast. Well that clunk is the simple plastic valve shutting off the flow of water. If the clunk is bad enough any poor or weak seams on your houses water supply will eventually leak, being shook apart.

Now imagine that same clunk happening in your fuel rail, 2100 times a minute just at idle.

The PD smooths out those clunks from the injectors, not a surge from the fuel pump.

And even some better homes have PDs on there water supply. Its not just something an engineer deceide was a good idea years ago.

And your post clearly convinces me more that people are replacing the PD and not even knowing what they are bypassing.

Go ask any dealer, or company like Racing beat or Mazdatrix, if they are using Banjo bolts, or if they are doing it the right way and just replacing the PD when they get old.

I knew exactly what I was removing and I can say that I havn't observed any noticable problems with it.

I've also heard that removing a PD can *potentially* lead to a blown engine. See, the PD serves to equalize the fuel pressure in the fuel rail. Without a PD, there are times when the fuel-pressure in the rail is lower than it should be due to the pulsing of the injectors, especially under heavy load (large amounts of boost, etc.) Now, i've never really heard of anyone blowing their engines because of this, but it certainly could happen.

Don't think so, but I could be wrong. The pressure in the fuel rail would never drop below the pressure controlled by the rgulator. If your stuffing fuel into the rail one way from the pump, and you get backpressure from the injectors opening and closing, you'd never get less pressure, it would be more. There's no where for the fuel to go to drop the pressure. Least that's how I figure it....

Another bypass would be to convert to a parrallel system like the one outlined on www.fc3s-pro.com

The use of stainless steel lines is not essential, and that would help to keep the cost down. Realistically, it's for looks. You will have to buy a aftermarket FPR, but I think in the long run you'd save money, especially if you plan to upgrade in the future.

Is there anyone out there that makes an inline PD that is less prone to failure then the stock Mazda part? I personally have no issues with running custom steel lines. I understand the porpose of the PD, and would like to keep one, but I just don't want my baby turning into a pile of burnt metal and plastic. Hence the desire of running a banjo bolt.

i guess it all depends on how paranoid you are....when i made my car a tree-hater, i redid a bunch of stuff....i replaced my fuel lines, put in the banjo bolt amoungst other stuff

Corprin, honestly, if you replace the pd every 6-7 years you wont have a fire caused by the pd.

Ok, this is (a post I was going to make on the archived thread a while ago) based on a decent grasp of physics, what I've read here, and in the archived one, and some life experience. My sink does the same thing when I turn on and off the water fast, you can hear the pipe bounce a few times inside it's hangers. Playing around with turning it on and off different amounts (the whole way, but with a restrictor valve so I knew I wasn't just opening it more) I verified well enough for me to consider it proof for myself that if the line was open when the pulse hit back or away, it would shoot out more or less water. Now this tells me a few things. For one, this along with your(plural and unspecific) fuel pressure gauges tells me that no PD = Pulsing. It also tells me that without some sort of limiting factor the pulses will get through the line. This tells me that unless the injectors are stopping the pulse somehow, it is getting into the engine, and that causes rich/lean variance. No, it won't likely make your motor run rich or lean, more likely it will make it run rich or lean for one combustion, and if lean, that's the one that'll detonate.

just my 2c

BTW... if shutting off the water in my kitchen sink real quickly could break the pipe in my basement eventually, but my house had come with a device to relieve that pressure, but that leaked after a while, and was mounted right above my circuit breakers, and take out my electricity... that sh|t's getting taken off, but my basement is empty, brick and concrete, has a good drain, and everything in my house is electric...

Additional response to GatorRX: If the pressure change is coming from the very end of the line (injectors) nothing before that short of a PD is guaranteed to stop the pulse... the pressure at the regulator could be one PSI, and there could be lower PSI after it (higher as well then, but that's why it's a pulse) correct me if i'm wrong someone

wow, sorry I didn't check the date on this one :) oh well, at worst someone read it again