3FE Pulse Damper 23270-73010

ColoradoBoy

Too many interests, not enough time...
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I have dug into some issues (some PM, some chasing my low idle issue) and have found that the screw in the top of this damper has come out. (captured by the plastic protective cover on top) In your 3FE experience, can this be screwed back in with a drop of Loc-Tite & be good, or am I better off installing a new part? Could this be part of my low idle (OK when starting cold, dropping to less than 650 RPM when slowing/stopped & in gear; getting worse as the operating temperatures get higher; chug-chug-chug) issue? I imagine that the screw is holding some sort of valve assy to keep fuel at a consistent pressure/flow?

I currently have the injectors out for a rebuild (WitchHunter) and would like to take care of this fuel damper while it is easy to get to. I'm also installing a new gasket for the push rod cover (wow, 30+ year old cork gasket is HARD!) as part of my attempts to eliminate vacuum issues that my be contributing to the poorly running motor. After getting the cover off, I noticed that the push rods for #6 cylinder are very loose, compared to the rest. I'm betting that I did not get things re-tightened properly when I adjusted the valves last month, so I'll be doing that again as I put everything back together (and could potentially be part of my chug-chugging when running, if both the intake and exhaust valves for #6 are way too loose?). Looking at EGR and Air Pump delete, as I already have things torn apart, and once done, eliminate a bunch of hoses/systems that also simplify troubleshooting moving forward.

Items that have been addressed/replaced to date:
new rubber boots for air intake
EFI Relay: 28300-16010
OEM fuel pump
OEM fuel filter
Fuel Pressure Regulator, 23280-74100
Fuel Pressure Damper 23207-20011
OEM spark plugs, wires, dist. cap & rotor (also pulled distributor, cleaned and re-set gaps, new o-rings)
Valve cover gasket & grommets, PCV valve, grommet & hose
OEM Throttle Position Sensor
AFM tested and verified as good
oil dipstick in good shape, added small o-ring to try and help any potential vacuum issue
Charcoal Canister Rebuild
Vacuum hose replacements & tube cleaning (still finishing up- a few hoses left to complete)

Anything major that I'm overlooking related to the low idle issue?

Thank you again to the MUD community and help!
 
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I have dug into some issues (some PM, some chasing my low idle issue) and have found that the screw in the top of this damper has come out. (captured by the plastic protective cover on top) In your 3FE experience, can this be screwed back in with a drop of Loc-Tite & be good, or am I better off installing a new part? Could this be part of my low idle (OK when starting cold, dropping to less than 650 RPM when slowing/stopped & in gear; getting worse as the operating temperatures get higher; chug-chug-chug) issue? I imagine that the screw is holding some sort of valve assy to keep fuel at a consistent pressure/flow?
The FPD is a pressure vessel exactly like an expansion tank in a circulating hot water home heating system. Its job is to minimize fuel pressure fluctuations as the 2 sets of injectors fire.
While I doubt this would cause your rough running issue, it should be replaced with a new OEM part.
Your issue sounds more like faulty O2 sensors or bad O2 sensor connections. From a cold start the O2s are not in system and slowly come on line as the coolant temp climbs towards NOT.
 

ColoradoBoy

Too many interests, not enough time...
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Joined
Jun 17, 2018
Messages
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Colorado
The FPD is a pressure vessel exactly like an expansion tank in a circulating hot water home heating system. Its job is to minimize fuel pressure fluctuations as the 2 sets of injectors fire.
While I doubt this would cause your rough running issue, it should be replaced with a new OEM part.
Your issue sounds more like faulty O2 sensors or bad O2 sensor connections. From a cold start the O2s are not in system and slowly come on line as the coolant temp climbs towards NOT.
Thank you again, Jon. I'll get a new part on order. Got new O2 sensors soon after picking up the rig when we replaced the exhaust front-to-back. I would hope that those parts would last longer, but you can't trust anything these days... I'll check into that.

And pics of the progress as she sits today:

IMG_7435.jpg
IMG_7430.jpg
IMG_7456.jpg
 
Joined
Aug 26, 2007
Messages
189
Location
Baton Rouge, LA
In my experience with rough low idle, especially when cold, vacuum leaks are usually the culprit because the vacuum hoses are stiff and dont make a good seal. You might also want to clean your idle air control valve and its seat in the manifold. Check the cold start sensor circuit and associated vacuum lines, but I have removed that completely due to living in Louisiana. My 3fe is never really smooth cold start in cold weather because I have removed the EGR and the cold start system but once it goes into closed loop it runs great... unless there is a small vacuum leak or the IAC valve is dirty. Most of the time it is in high idle because the AC is running, again, Louisiana.
 

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