Fuel Pulsation Dampener

Justin

Justin

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Mar 31, 2005
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Can the fuel pressure dampener go bad? From what I found its fairly useless... does anyone contradict that? The NA's don't have one so I figured I'd just pull it off and replace it with the lines from the NA. Unless there are flexible lines avaliable? Hmmm?

Basically I wanna know if there's any reason NOT to remove this.....
 
lagged

lagged

1991 1JZ
Mar 30, 2005
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i got rid of mine. see mkiiitech.com for part numbers of fittings.

the only thing that i have noticed is more noise that i can hear in the cockpit.

my fuel pressure stays stable and reacts how it should while driving.
 
Justin

Justin

Speakers?
Mar 31, 2005
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lagged said:
i got rid of mine. see mkiiitech.com for part numbers of fittings.

the only thing that i have noticed is more noise that i can hear in the cockpit.

my fuel pressure stays stable and reacts how it should while driving.
Click to expand...


I dont' know why I didn't think of mkiiitech in the first place :p

I'm going to get an AFPR here shortly so i think i'll do both at once...

thanks man :
 
Nick M

Nick M

Black Rifles Matter
Sep 9, 2005
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I hate to say it, but it is more over engineering by Toyota. The intention is just as the name implies. When the injector opens, it leaves a nice gap of air. The pulsation dampner is another way of increasing pressure so you dont have that gap but for a very short time. And GE's do come with one. And yes, they can go bad. There is a screw in there that can work its way loose. You aren't supposed to actually do anything with it, no adjustments, etc. With a high volume pump, you can probably easily get away with not having one.

This is a by product on not having sequential injection.
 
lagged

lagged

1991 1JZ
Mar 30, 2005
2,616
0
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new rochelle
Nick M said:
I hate to say it, but it is more over engineering by Toyota. The intention is just as the name implies. When the injector opens, it leaves a nice gap of air. The pulsation dampner is another way of increasing pressure so you dont have that gap but for a very short time. And GE's do come with one. And yes, they can go bad. There is a screw in there that can work its way loose. You aren't supposed to actually do anything with it, no adjustments, etc. With a high volume pump, you can probably easily get away with not having one.

This is a by product on not having sequential injection.
Click to expand...

i think later model GEs didnt come with it.
 
3p141592654

3p141592654

90T
Oct 11, 2005
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The purpose of the FPD is to smooth out the pressure spikes that occur when an injector closes. These spikes are too fast to be seen by a typical fuel pressure gauge. It is entirely analogous to water hammer that occurs when you shut off a water valve quickly in your home. The spikes do cause stress on the fuel system and injector pintles, and increase noise. If you don't care about long term reliability and noise then by all means remove it. Toyota built its reputation on reliability, which is why they include the device. The auto industry is very bottom line driven, so the inclusion of parts with no function is not going to happen.
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
I wouldn't call it useless or even over engineering. It's an example of proper engineering, of Toyota doing things "right" to a fine degree. As Nick said, it's there to dampen the jitters in fuel pressure caused by the injectors opening and closing. You can't see them on a fuel gauge but if you look at fuel pressure with an electronic presssure sensor and a scope the differences between dampener/no dampener are apparent. It actually does a decent job of smoothing things out.

It is needed? Technically, from a hydraulic engineering standpoint, yes. You may not feel anything with it removed but any variations in fuel pressure effect the amount of fuel injected. It's your call but it's not useless and does what it's supposed to. My opinion is it should be left in, if only because by removing it you're making the system less precise. It's akin to taking the second hand off a fine watch. The dampener also provides a quick and dirty method of verifying fuel pressure.

* I see 3p beat me to it and nicely done too. Water hammer is a very good analogy.
 
IHI-RHC7

IHI-RHC7

"The Boss"
Apr 1, 2005
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My question would be in reguards to it's level of restriction.
Are there any people making over say 500 whp with their fpd intact?
 
IHI-RHC7

IHI-RHC7

"The Boss"
Apr 1, 2005
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I see.
The way I saw it when I disassembled mine was that the fuel enters through the banjo fitting in typical fashion, but there is no hole in the banjo bolt to feed the rail, instead fuel flows upwards into the fpd and down through a hollow stud to which the fpd is fixed.
If that is correct, fuel must flow through the fpd to get to the rail, albeit the fpd "part" is sitting above the hollow stud... Gotta go, I'll check back around noon...
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
Makes no sense. There should be a hole in the banjo bolt to feed the rail. The dampener just screws into the end of the rail to provide a spring loaded volume. It sounds like you're referring to the fuel pressure regulator, not the dampener.
 
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lagged

lagged

1991 1JZ
Mar 30, 2005
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new rochelle
well, for anyone wanting to upgrade to -6an stainless steel fuel lines, summit DOES carry AN banjo bolt fittings, if they have an appropriate size i dont know, but its worth checking out for those interested.
 
IHI-RHC7

IHI-RHC7

"The Boss"
Apr 1, 2005
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No, I concurr that it doesn't make sense, but I'm pretty sure fuel must travel through the damper before the rail, I remeber being a tad bit horrified when I looked at it last time.
I'll dig one up and look at it. Looking at the EPC, the stud is an integral part of the FPD and the fuel does flow into the FPD before it feeds the rail. I'll have to get one in hand to show what I mean...
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
Huh, no kidding. Now I'll have to go pull mine apart to see. Damn you guys ;)

*edit* I stand corrected. You're right Jake. It is on the feed side. I checked my TCCS books and the breakdown is in there. It's acting more as a regulator than an accumulator. Damn, learn something new everyday. That makes your orignial question valid but I'm not sure the resrtiction would be an issue as long as the pressure was upped enough.
 
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boost fiend

boost fiend

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Jul 24, 2005
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so if it is on the feed side and could be chucked in theroy, would it really do anygood to be there in a situation where theres a 255 fuel pump in the tank, if the fpd is calibrated? just a thought.

it is kinda a weird lil device they put there.
 
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