Pulsation Damper replaced with Banjo Bolt
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Pulsation Damper replaced with Banjo Bolt
Taking my injectors out, I noticed the infamous pulsation damper (PD) loose screw, complete with gas leaks. Not wanting to add my car to the list of roadside BBQ hosts, I want to stop the leak. They way I understand it, there are three options.
1.) Replace with a new PD $124.51 (Mazdatrix Price) 2.) Swap fuel rails with a 88 - 91 which have built in PDs. Or 3.) Replace PD with a banjo fitting bolt.
Has anyone replaced their pulsation damper with a 12mm x 1.25 banjo bolt? If so, did you notice any adverse changes in how the engine ran?
I've got a feeling that a leaking PD with a screw missing isn't doing a great job of dampening anyway. So replacing it with a bolt may be alright.
1.) Replace with a new PD $124.51 (Mazdatrix Price) 2.) Swap fuel rails with a 88 - 91 which have built in PDs. Or 3.) Replace PD with a banjo fitting bolt.
Has anyone replaced their pulsation damper with a 12mm x 1.25 banjo bolt? If so, did you notice any adverse changes in how the engine ran?
I've got a feeling that a leaking PD with a screw missing isn't doing a great job of dampening anyway. So replacing it with a bolt may be alright.
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http://haxx0r.net/car/rx7/pulsation.html
I got *TWO* 89-91 fuel rails, each for under 30$. If you aren't under a time constraint, i suggest you look around on the for sale section here, and at http://www.thepartstrader.com for people parting out 89-91's..
-Tesla
I got *TWO* 89-91 fuel rails, each for under 30$. If you aren't under a time constraint, i suggest you look around on the for sale section here, and at http://www.thepartstrader.com for people parting out 89-91's..
-Tesla
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OOpps on my first post I meant to say '89 - '91 fuel rails have the built in PD.
Do used '89 - '91 have rubber diaphragms built in? If so, aren't they likely to be cracked being at least 10 years old?
Anyone out there with banjo bolt experience?
Do used '89 - '91 have rubber diaphragms built in? If so, aren't they likely to be cracked being at least 10 years old?
Anyone out there with banjo bolt experience?
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another option for ya... i bought a new one for my 87n/a,but,was unable to use it 'couse i'm using a 89-91 intake manifold,and there is not enough clearance for the older pd under there.so,if you want it,make me a offer.i'm thinking in the 80$ range.
david
david
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uhhhh, if the damper is suppose to smooth about the fuel pump bumps wouldnt just a bolt defeat the purpose? I jsut wanna know, ****, Ill put a banjo in there if it means no way of leakin.
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If the pulsation damper has a loose screw and is leaking (which mine was), I don't see how that does a good job a smoothing out the fuel pulses. So my thought is, a damper may not be necessary.
I am having a hard time finding a 12mm x 1.25 banjo fitting bolt. Anyone know where to search? I have looked into local fastener houses, J&L, McMaster Carr, some Aeroquip catalogs, made some calls and still haven't find one.
-john
I am having a hard time finding a 12mm x 1.25 banjo fitting bolt. Anyone know where to search? I have looked into local fastener houses, J&L, McMaster Carr, some Aeroquip catalogs, made some calls and still haven't find one.
-john
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Originally posted by noboost
If the pulsation damper has a loose screw and is leaking (which mine was), I don't see how that does a good job a smoothing out the fuel pulses. So my thought is, a damper may not be necessary.
I am having a hard time finding a 12mm x 1.25 banjo fitting bolt. Anyone know where to search? I have looked into local fastener houses, J&L, McMaster Carr, some Aeroquip catalogs, made some calls and still haven't find one.
-john
If the pulsation damper has a loose screw and is leaking (which mine was), I don't see how that does a good job a smoothing out the fuel pulses. So my thought is, a damper may not be necessary.
I am having a hard time finding a 12mm x 1.25 banjo fitting bolt. Anyone know where to search? I have looked into local fastener houses, J&L, McMaster Carr, some Aeroquip catalogs, made some calls and still haven't find one.
-john
The 89+ rails have the pulsation dampner built in. It's integral to the rail, and is designed so that it isn't as prone to leaking as the 88's are.. In fact, I've never heard of an 89+ with an engine fire, or a leaking PD.
Someone on here has an animated gif of the difference between the two.. he'll prolly chime in in a bit..
-Tesla
#10
If any one has questions to the exact specs heres the web page from Holley/Earl
Banjo Bolt Page info Click Here
Banjo Bolt Page info Click Here
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#13
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a banjo bolt is a bolt that has the center drilled out up to the head and a
....................___.....
______ ...__l.....l
l______l..l__.....l
__________l.....l
l_________ ......l
...................l___l....
hole drilled in the side so that fliud can pass through it, above is a cross section
Justin
....................___.....
______ ...__l.....l
l______l..l__.....l
__________l.....l
l_________ ......l
...................l___l....
hole drilled in the side so that fliud can pass through it, above is a cross section
Justin
Last edited by RX-7Impreza; 03-09-02 at 04:55 PM.
#16
I wish I was driving!
The pulsation dampner "damps" pulses from the fuel pump, a mini gasoline shock absorber. As I see it, this allows the fuel injectors to see an ABSOLUTELY constant fuel pressure. Otherwise, the injectors could fire at either a pump pulse or the time in between, where fuel pressure would be higher or lower. Higher or lower fuel pressures would allow minute differences in air fuel ratios, and with the engine running at the very edge of it safe level, you *could*go lean....
I would keep it if at all possible, unless you switch to a better style pump, such as an Aeromotive A1000 linear pump or the likes. That's what I run.... (almost). I have a sweet fuel set up.
Sean Cathcart
I would keep it if at all possible, unless you switch to a better style pump, such as an Aeromotive A1000 linear pump or the likes. That's what I run.... (almost). I have a sweet fuel set up.
Sean Cathcart
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despite the strength of the fuel pump you have you will still endager your car somewhat by doing the banjo bolt fix. with the injectors flicking open and closed so often you can create "dry spots" where the injectors open with not enough pressure to inject much fuel. this is minor but in high hp/ boost engines it can be a danger.
it is much better to get teh S5 fuel rail, they arent hard to locate...
Justin
it is much better to get teh S5 fuel rail, they arent hard to locate...
Justin
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Pinfield357,
The Banjo bolt takes the place of the pulsation damper. On the end of the primary fuel rail there is a pulsation damper that sandwiches a banjo fuel hose fitting (called a banjo fitting due to it's banjo shape). The pulsation damper can be removed and a banjo bolt can be installed. The banjo bolt sandwiches the stock banjo hose fitting onto the fuel rail.
So to answer your question "where would the gas go?" It would flow through the banjo bolt, which is hollow.
FWIW, I replaced my PD with a banjo bolt and saw no ill effects of idle quality.
-john
The Banjo bolt takes the place of the pulsation damper. On the end of the primary fuel rail there is a pulsation damper that sandwiches a banjo fuel hose fitting (called a banjo fitting due to it's banjo shape). The pulsation damper can be removed and a banjo bolt can be installed. The banjo bolt sandwiches the stock banjo hose fitting onto the fuel rail.
So to answer your question "where would the gas go?" It would flow through the banjo bolt, which is hollow.
FWIW, I replaced my PD with a banjo bolt and saw no ill effects of idle quality.
-john
#23
Originally posted by Pinfield357
ok i understand the the banjo bolt is hollow and the fuel flows threw it but where does it go once its threw the bolt? it has to go some where
ok i understand the the banjo bolt is hollow and the fuel flows threw it but where does it go once its threw the bolt? it has to go some where