roelker87

What exactley does this do? What would symptoms be ifthis wasent working correctley? Could it be vapor lock like symptoms?

roelker87

Its a 95 3.0 3vze

SoCal4Running

It is supposed to even out the fuel pressure. The fuel pumps output is not smooth but rather pulsing as it preasurizes the fuel.

The pulsation dampener is a spring diaphragm that evens out the pressure in the fuel rail so the injectors all have the same pressure behind them when they open.

Don't think a faulty dampener would show ip as vapor lock.

93toyrunner2

If you take off the plastic cap, and turn the screw all the way in, your fuel pressure will be extremely high. I did this without realizing it, and had to replace all my connecting rubber fuel line (old) with new injector fuel line. The old ones just started leaking everywhere.

roelker87

So my problem is after driveing about 15 miles and parking for about 20 mins wont start up or will start go to 500 rpms and die. But if I crack the cold start injecter it will start up. Or if I leave it for an hr or so it will start up. Have replaced fuel pump and relay fuel pressure regulator egr plugs cap and roter mass air flow. Have spark at coil and plug, replaced fuel cap and have tried 3 differant fuel treaments, and can't figure it out

roelker87

I can drive to work and home fine but if I have to run around town it will do this almost everytime I shut it off

roelker87

Have also replaced upper intake manifold and cold start injecter

roelker87

Have also replaced ecu

xxxtreme22r

sounds like a failing ?? COR (circuit opening relay) ?? aka cold start relay. the COR is basically the EFI's version of the electric choke if I understand it's operation correctly. I might be slightly wrong, but I know I am in the right ballpark. Your check engine light doesn't happen to be on would it?

roelker87

No check engin light. It was on said starter signal circute vss cir, and egr malfunction fixed the egr and starter signale. Reset light and hasn't come back on

myyota

I doubt turning the screw in all the way on pulsation dampener will cause extremely high fuel presure. The fuel presure regulator set the fuel presure, not the pulsation dampener

MudHippy

That's correct. As a matter of fact the screw does nothing to affect the function of the dampner. It doesn't even need to be there. I know why it's really there, but I'm not going to start a debate about it. You figure it out, it ain't that inobvious.
Right, except for the fuel pump being the cause of the pulsation part. These engine's use a turbine pump which has less discharge pulsation than the older rotor cell pumps. The injectors are the real cause of any significant pulsations in the fuel rails, requiring the dampner to smooth them out.

myyota

Actually the screw needs to be in the bottom of the damper or it will leak fuel. When i got my 4Runner i had to replace the damper because the screw had fallen out and was leaking fuel, its not a cheap part either, a new one is around $100 dollars, but i was able to find a good used one for half of that.

MudHippy

It's not possible for the screw itself to stop a leak under normal conditions. One of the reasons it's there is to potentially stop a leak from occuring though, not gonna say how though. But I will tell you one thing for sure. If you go remove the screw from your new one right now, it's not going to leak. It takes another process, which wouldn't happen under normal conditions for the leak to arise. The reason being that these systems are always highly pressurized(fuel pump running or not). Hence, the screw is useless/does absolutely nothing. It's just a neat little ornament sticking out to tell you there's pressure in the system. I have no idea how many thousands of miles mine had the screw riding around in the plastic cap...I'll bet it was quite a few.

myyota

On the new used one that i got the screw on the bottom of the damper had an o-ring on it.
On the 90 and newer 22RE`s, they no longer use a damper, they replaced it with a banjo bolt. Maybe they found out that the damper wasn`t necessary so it was eliminated. Whats your opinion on this ?, i was thinking of finding a banjo bolt and installing it in place of the damper, it would be one less thing to go wrong. Your opinion ?.

SoCal4Running

It's not uncommon for the screw to fall out of the dampener and lay in the plastic cap. It will NOT leak with the screw out and the dampener does NOT set the fuel pressure.

myyota

When i got my 4Runner the screw on the bottom of the damper was missing, and it was leaking gas. Maybe the diaphragm in the damper was bad ?. Either way, once i replaced the damper it was all good.

DavidPayne

How hard was it to replace the fuel damper? Did you have to pull the air intake chamber to replace. I think my damper is leaking. Can't tell for sure because I can't see the whole thing but gas is leaking like crazy in that general area.
Thanks for the help.

SoCal4Running

On my 86 it's not hard to change. Remove intake tube and it's able to be removed with a wrench.

The intake plenum can stay on.

Kalihi,HI

Aloha from Hawaii,
I had to pull my plenum to change my PCV and decided to replace the injectors as well as they were very old and gunked. In removing the fuel rails, I noticed the screw in my pulsation dampener was out and sitting in the plastic cap. I did not have any fuel leaks. As I put everything back together, how tight/far in should I screw the screw in the pulsation dampener? Also just because the screw was out doesn't mean I need to replace the dampener right? Lastly, has anyone ever heard of a type of gasket made for brake and fuel lines that has a rubber lining on the inner circle of the gasket? I bought 8 to replace my old gaskets for the No.2 & 3 fuel pipes to the fuel delivery rails as no one in Hawaii carries those gaskets. The shop I bought them from told me they are a newer type of gasket that is the right size and they told me it should seal even better than the original gasket. Also if my old gaskets look fine, do I really need to replace them?