Howi

iTrader: (2)

my i ask where did you "look into" to get this info?
many american cars don't have it (such as your suv, stangs.... etc) don't have PD's cuz the injectors spray continuously, not like our 7s.

Icemark

I don't know who was smoking what when they told you that the PD was to smooth pulsations from the fuel pump, but that would be radically wrong.

And its is common for Ford to use a integrated PD/FPR on their cars. I would have to see a fluid schematic to tell you for sure if the exploder you have (which has had factory recalls for fuel lines popping and coming off) has one.

As NZ says, you can't compare a varible nozzle that limits flow to an injector which switchs on a off flow.

Icemark

From their web page (and many others):

NZConvertible

A parallel rail arrangement doesn't change the need for a PD, so whatever the advantages are, they don't include eliminating the need for a PD.
You were misinformed. Most automotive fuel pumps are impeller types, so there are no pulsations generated by the pump. As has been explained many times before on PD threads, the pulsations are generated by the opening and closing of the injectors. I'm not doubting your knowledge of jet engine fuel systems, but automotive EFI systems work very differently.

NZConvertible

Only mechanical fuel injection sprays continuously. All EFI systems use pulsed injectors, whether they're made in the US or elsewhere.

cluosborne

I've been searching, and researching almost every post on this subject in preparation of pulling, rebuilding, and installing the motor in my 1988 GTU.

At this time, I'm not looking for high performance gains, or putting in a standalone fuel injection system. I just want to perform as clean, reliable, and *safe* an installation as I can.

I'm concerned about the risk of fire if I simply replace the PD with a new OEM one and it fails. If I put in a Banjo bolt or elimination kit, that would elminate such a risk (with the installation of new fuel lines).

So... for stock or mildly modified cars, is the banjo bolt a permanent solution or not?

If not, excluding the science and terminology that has so passionately been used, why? What problems would arise?

Will using a new OEM 86-88 PD increase or decrease the risk of fire? (Risk of fire is the one thing that is making me consider elminating it.)

If the PD did fail and started leaking fuel, is there a way to keep raw fuel from ending up on the exhaust manifold? Could it be directed away?

Finally, regardless of what I do, where I can a get a set of stock fitting SS or rubber fuel lines?

ERAUMAZDA

Jet engines go through the otto cycle but the spary is continous. That is why a PD is not needed. Injectors

Icemark

I personally believe that not using a PD and using a banjo bolt increases the possibility of fuel fire tenfold, because of busting, leaking, or loosening fuel lines. Using a banjo bolt to prevent fires is like using a nail to patch a tire. Yeah it works, but would you want to drive on a 1000 miles with it?

To top it off you have the fuel delivery issues as mentioned above.

Yeah there are people that say they have driven for years with a banjo bolt without any problems, but there are also people that have blown engines or bust fuel lines. Could they be related??? Hard to say, but do you want to be the guinea pig? There have been proven and duplicable issues however (when a PD is not used) on other cars.

Mazda put a PD on, because they felt the injection system required it and they have built and tested a lot more cars than any of us have.

It is very very very unlikely that a new PD would fail, in less than 50-100K miles unless there is another issue (such as high under hood temps from replacing the stock fan with some insufficient one, or a oversized turbo and no heat shielding, or other similar problems).

New fuel line can be found almost anywhere. Remember SS ones should be fuel line specific and covered with some sort of protection to prevent sand, grit, and dust from getting in between the SS braids when SS lines are used on a street vehicle.

Project84

I looked at 3 different websites for companies that make pulsation dampeners, but what do they know? I also ran across a kit that is designed to by the fuel PD on the 93-98 Supras, But nobody would ever remove or bypass the fuel PD. Everyone knows at least 10 people who did that and the fuel injectors shot out so hard that they cracked the block. Just ask around on this forum. Look at how many threads there are about people wishing they never replaced their leaking PD with a banjo bolt.

Yo, I'm done with this. Y'all do your own thing and I'm gonna do mine.

cluosborne

Thanks, Icemark, for replying.

NZConvertible

They use the Brayton cycle, not Otto.

sectachrome

they should last 10+ years, i dont see the big deal in just replacing it with another PD. theyre not even expensive.

phinsn98

iTrader: (2)

Well it turns out it wasn't the PD it is the fuel preasure regulator which is apparently on the secondary fuel rail. As far as it not being a big deal, I can think of something else I'd rather spend $125 on. I can't quite figure out where the cost comes from but again it's more then I'd like to spend for something like that.

late

NZConvertible

J-spec motor.

asherwood

After all that I have read, I agree, JUST REPLACE IT!

But, where I am, inexpensive is not what the dealer charges...$215CDN

asherwood

Damn, double post!

phinsn98

iTrader: (2)

No it's not a Jspec motor...Mazda reman

NZConvertible

Oops sorry, got that mixed up.

Sergei The Saint

Will that one fit on a S4 t2? Rex4KLife?

RETed

I know of at least half a dozen FC owners with banjo bolts, and they have zero problems.  The amount of rubber fuel line already in the car is enough to dampen any pulsations in the fuel rail.  These cars all run stock sized injectors, so I dunno how a large (i.e 1600's) injector system would react to a banjo bolt - it doesn't matter as high performance motors running 1600's (under standalone EMS) control all would easily have a parallel rail system with an aftermarket FPR.

We can argue this back and forth, and I don't see nay-sayers prove a banjo bolt will cause fires due to loosening hoses.  I know Mazda's PD design will eventually fail - no one can deny that.  I know the banjo bolt works through my experience, and that's good enough proof of that.

Remember, the sheer volume of fuel throughout the fuel system damps itself - we're not talking glycol-based brake fluids here.

Keep in mind that the fuel injectors all switch to batch.  I think fuel system running sequential injection are more susceptible to pulsations due to injectors firing out of phase?

Also, that "water column shock" analogy is only remotely applicable here.  The primaries are not dead-ended - the pulses can still travel upstream, where it will eventually hit the fuel filter, or downstream into the secondaries.  The secondaries are almost the same, but the pulse can either hit the primaries or back out the FPR.  Remember, there's a SHORT LENGTH OF HOSE that connects the two rails, so that is a damper in itself.

We can over-analyze the whole scenario, and it still comes down to a $10 banjo bolt, or a $100+ piece of junk that WILL leak in the future.  It's your choice.


-Ted

WAYNE88N/A

i,ve been an aircraft mechanic/ inspector for goin on 20 years, and i,ve never heard of these otto/ brayton cycles you guys are talkin about. Is that something in the school textbooks? Our jet's cycle is 1)suck 2)squeeze 3)bang 4) blow!!! on a related subject, anybody know if the o-ring on the fuel press reg is the same size as the injector o-rings? Just r/r my PD too, and can't stand putting 16 year old o-rings back in!

Sergei The Saint

Speaking of those rings, I found a couple black O rings when I was taking off the fuel rail. Do I need to put these back, because I cant seem to find where they go.

NZConvertible

I hear what you're saying, and I'm not necessarily saying you're wrong, but I've also yet to hear any banjo bolt proponents answer the question I asked earlier. If they aren't necessary, why does nearly every EFI car ever made have one?

You don't need to have an in-depth knowledge of thermodynamic cycles to know how to fix the engines that use them. All 4-stroke petrol engines use the Otto cycle or a derivation of it, and all jet engines use the Brayton cycle. Stick those names into Google and you'll get tons of info.

STR8BALLIN - R

is that your 7 in the avatar, any large pics of it? thing looks badass!