pulsation damper removal

Guest · Jun 15, 2003

well the head gasket job is done, and the motor fired up right away and no leaks... well almost. the fuel pulsation damper was damaged when i removed the fuel line. and i'd rather swap it out than pay big dollars to replace it.
so can anybody reccomend the easiest, ie least time consuming way to remove it ?? ideally there'd be a banjo bolt that is a direct swap for the FPD. realistically though i'd be surprised if there was , as the FPD is a different size on each side of the fuel line fitting.
How about swapping on a fuel line from a 7MGE, as they don't have an FPD. Is the fitting and banjo bolt the same thread size as the 7mGTE ???

flubyux2 · Jun 15, 2003

you dont really wanna do that... the pulsation damper is there to dampen out the pulsation that is caused by the rapid opening and closing of the fuel injectors...

think of it like the water pipes in an old house: you are brushing your teeth and then you turn the water off... you just turn it off cuz thats what you do... then all of a sudden, you hear a weird, almost scary rattling sound of things clanging together inside the walls... thats called Water Hammer effect, and tis caused by the rapid closing of the water valve... almost like the compressor surge when you close the throttle and dont have a BOV to vent the pressure that will build up...

so you see, the FPD is there to alleviate the "water hammer" effect... if you take it out... things will brreak in the future... just liek water hammer in an old house causes the pipes to break and leak inside the walls.

Trent · Jun 15, 2003

I'll agree and disagree with that one. I had one that kept backing out the screws in the top so mine did not good. When the bigger fuel system was put in, I had the fuel dampener bypass installed. It's a stainless line that goes back to the feed line under the car and has a fitting that will go into the fuel rail and also has the necessary fittings to mate to that adapter as well as the fuel feed line. I've had it for quite some time and never had a problem. The person I purchased it from also never had any problems either. I don't see any reason why not to put something better in it's place. It's a restriction in my eyes.

flubyux2 · Jun 15, 2003

well, i personlly dont know of any particular failures related to the FPD sooo... with that being said... feel free to remove it...

but the FPD is there for the exact reason i just explained... i guess Toyota had soemting in mind when they designed the fuel system and wasnt exactly for all-out power w/o compromise.

so, i guess, the next thing would be to install an AN fitting and run all the way down to the little J pipe and eliminate that too... How bout that Trent?

btw, the FPD is just another point of failure... FC3S have had problems w/ FPD failures, leaking fuel and causing engine fires soo... best to just eliminate another potential problem.

Trent · Jun 15, 2003

Yes mine eliminates that J-tube also. That is one of the things I have going in my head right now to do when I get to MVP. They currently supply the same kit for the MKIV's to bypass that POS as well. I can assure you it will be made available

drjonez · Jun 15, 2003

the FPD is another source of failure/restriction. the MKIV guys have identified the screw backing out to cause a drop in fuel flow, a few guys have lost engines to this. if do you do keep the FPD, just make sure you have that screw in TIGHT. toyo put it in place for NVH reasons....

as for removing it via SS lines/fittings, search the SOGI archives, there are several good writeups on it.

FWIW i have been running sans FPD and J-block for over 3 yrs.....no problems, no increased noise, etc.

Larry_A · Jun 15, 2003

Opinions Everywhere

Why is it I find myself in the position of Devil's Advocate so often?

According to AEM, the FPD serves a significant role, & should always be used in high-pressure fuel inj applications.

From their EFI Basics doc w/the EMS:

"Measures must be taken to eliminate excessive pulsations in the fuel rail so the injectors get even fuel flow."

In another section:

"In applications where a new fuel system must be installed, a fuel pressure dampener is integral to ensuring consistent fuel flow to the injectors."

Key word: integral

Insofar as the Toyota unit's screw coming loose, that failure is way over rated, IMNSHO. I won't deny the possibility, but I've disassembled an FPD, & played with a new one. Neithr one could move, even with the screws sitting on my desk. In fact, upon removal of the old one, the screw was sitting on top of the unit, not lost due to the plastic cover. There was no way in hell that thing could move...unless you used a hammer on it, like I did.

Problems or not, the FPD does serve a purpose, & running w/o one will not provide the benefits that it imbibes. Are those benefits worth not having? They're not to the people who've discarded them.

My fuel rail is getting a -08AN line from the tank to a 'Y' of two -06AN lines, one into each rail end. The rail will have an FPD of some kind.

Guest · Jun 15, 2003

thanks guys for pointing out the FPD 's purpose. i'm not going to worry about it though. the way i see it is if 7MGE motors didn't have them and other 7mgte people are now running w/o them, then its not absolutely integral. how much could it possibly stabilize the psi anyways ?? i dissected an fpd and the spring in there is quite stiff w/ very little allowable travel for the diaphragm. that translates to very little pressure change and also when considering the large volume of a fuel rail . so it's only going to stabilize the psi by eliminating a couple psi - if that - and when it's 40 psi or whatever it is on a 7mgte, i don't think a couple psi really makes a difference.

also - i already tried a second fpd i found at the pic a part and it also leaked. as far as i can tell they were both leaking from around the 'lip' , where the bottom half is crimped around the top half of the diaphragm casing.
as far as the little screw unit on top, it's too small and delicate for my liking. after 15 years of service i have my doubts as to how reliable it would be.
so considering that a new fpd is also huge coin i'd rather axe it and eliminate a possible cause of a potentially deadly fuel leak.

Larry_A · Jun 16, 2003

Metallion said:
.....the way i see it is if 7MGE motors didn't have them.....

If that's the logic you've chosen, then having a turbo doesn't serve as a point of differentiation, either.

..... and other 7mgte people are now running w/o them, then its not absolutely integral.....

I'm certain there are some very high HP engines in the world w/o FPDs. Just because something is possible, doesn't make it right. There are very few individuals who participate in this forum who are qualified to say the FPD is not integral, & we can agree that neither you, nor I are amongst them.

how much could it possibly stabilize the psi anyways ?? .....

I rest my case.

Guest · Jun 16, 2003

the non turbo engines do have them.if you need or want one i have a few laying around.

adjuster · Jun 16, 2003

Here's my .02.
Cheap FPD. Get about one foot of fuel line. The rubber type. Get a fitting that will adapt a standard fuel line barb end to it. Then plug the end of one side of the 1 foot long fuel hose, and clamp it on good. Then clamp the other end to the barb fitting.
The slight expansion of the rubber fuel line will "Dampen" the pulses. This will work up to the rated fuel line pressure. Generally more than your fuel system will ever see. No leaks, and less than 5.00 total cost. (Assuming you can get a fitting for where the stock FPD goes.)
What do you experts think about this idea? Stock type rubber fuel line expands with pressure, and contracts when the pressure goes away, if you don't belive it, grab your fuel line and feel your pump working, and then have someone shut off the engine and start the car again. Very easy test, and you will feel the line expand/contract. Same effect as expensive FPD, IMHO.

Guest · Jun 16, 2003

You could get another used pulsation dampener for like 5 dollars.

Why remove it? I don't get it. Obviously it has its place and purpose.

Manufacturers are not so stupid, as to be wasting money putting things on your car, that do NOTHING!

They would much rather make more profit instead.

The Non-turbo doesn't have the pulsation dampener (looking at the TSRM). The turbo does. So obviously there seems to be a need for it, with larger injectors, creating more pressure variations.

Seems like a good idea to me, to keep it.

Larry_A · Jun 16, 2003

The disclaimer hasn't been mentioned thus far, so here it is:

OEM FPDs will present a restriction at some point during the quest for more power, dependant wholly upon on how far one wishes to go. So if you really must flow more than it is capable of, either a larger FPD, or its removal will be nec.

That was for Adam.

Larry_A · Jun 16, 2003

Shawndude said:
The Non-turbo doesn't have the pulsation dampener (looking at the TSRM). The turbo does. So obviously there seems to be a need for it, with larger injectors, creating more pressure variations.

'87-'88 NAs have FPDs, verified. A '92 just checked moments ago, does not.

Guest · Jun 16, 2003

The FPD (sheesh more acronyms), is not really the restriction, it is the bolt that mounts it to the fuel rail. I can't see why you couldn't just drill out the banjo bolt openings larger, while still retaining the FPD.

I think the FPD is mounted there just for convenience, rather than having to be in that location. In theory the pressure should be equal throughout the fuel rail.

Here is a nice cross section picture of a FPD (see page 8):

http://www.autoshop101.com/forms/h22.pdf

toypro · Jun 16, 2003

All that as been said are valid points. I ran my 7m for at least a year without the dampner in place with 0 ill effects. It was removed when the fuel system was re-done. When I did the fuel lines on the 1jz, it was left out again, with the same 0 ill effects noted. The dampner on the 1jz is not part of the fuel rail, it is located on the motor mount fuel line bracket,but still used the same banjo style fitting. If I had seen a fpd that was a flow through type with -an fittings, I would have considered it when I did the 1jz fuel system,but I didn't look and if someone was to point one out to me now, I would not be going back and re-doing the lines.....

Guest · Jun 16, 2003

i went back to the pic a part today and found another fpd for 4$ so i'll try that out. If it doesn't work then as a backup i found a banjo bolt w/ same thread as FPD that's on both turbos and NA's. It bolts into the rear of the housing below the thermostat and is for the lower of the two turbo cooling lines, or on the NA the line loops up to the thermostat housing instead.
I have yet to try it but looks to me this bolt w/ an oversize washer could be used in place of the FPD .

flubyux2 · Jun 18, 2003

i would KEEP the FPD...just nto where it currently resides... its a smart position, right on the fuel rail, and absorbes the pulsations right there instead of making it travel further upstream thru the tubing. but, I agree, the BAnjo bolt is the problem... tyring to pump ~200 something liters per hour thru that stuipd little hole in the banjo bolt, after forcing it to make that sharp 90* turn, AFTER forcing it to circulate aroudn the banjo fitting is riduculous. If i had a choice and the means, i would eliminate every goddamn banjo bolt on the car. its more of a convenience item as far as assembly goes and less of a performance item as far as power production goes.

yes, i like convenience, but only to a certain point. i wont sacrifice piece of mind and power for my laziness. but i wont sacrifice piece of mind for convenience such as eliminated the FPD all together. I would just rig up something like Adjuster suggested, and keep it clipped to the fuel line so it stays out of the way and keeps a clean appearance.

pulsation damper removal

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