i have also seen were the 02 sensor wiring was messed up and wouldn't read correctly. I have just recently replaced an ignition switch on an older xj that was doing the same thing. The brown wire on the switch had burnt up.

 

What about a bad fuel pressure regulator? At least for the 50lb problem.

 

Clear Flood same for Renix.

 

Would that have anything to do with it "sometimes" starting during HNS if I press the pedal a bit? That's the ONLY way I have ever had it catch. Then it's ruff as you know what until it clears. I'm no mechanic but to me it's almost like it's flooded & has to clear.
Also those pressure readings are affected whether or not the gas cap is on or off. When on it drops 15-20 in just a few minutes. Off is when it goes up & sits there.

btw the CPS is fine.......especially after I drilled out the upper mount hole to 3/8 then re-mounted with down pressure.

 

Jw I had to just barely tap the gas peddle to get mine to run this afternoon after it had started. I quickly just tapped the gas very slightly when I did the jeep reved way up around 2500-3000rpm as if I had floored the gas all the sudden. Any idea what would cause this.

 

Bad TPS comes to mind.

 

I would like to see fuel pressure readings when it is hard to start. Leave the gauge on and secured somehow. I tuned my supercharged Miata with a fuel pressure gauge zip tied to the wiper blade so I could watch it through the windshield....

 

I'll do that tomorrow. I gotta get some rest now & quit thinking about that dynamite. I'll report back.......

 

Yeah. Don't let that fuse get too short. I admire your tenacity.

 

I don't want distract, but that there is one of your less complicated tests!

Not from Jeeps, but with some knowledge of regulators I don't think the spring should hold more than about 39#. If somehow there were crud in the line potentially it might lodge in a way to do that, block the release.

 

Yea, and if its sometimes 50 and sometimes low makes me think the spring maybe stuck and then sometimes after driving its unstuck. Pull plugs and check for flooding OP please

 

Ill have to check it soon then thanks to you I have a wonderful write up to follow

 

Or crap in the fuel return line? Dented fuel return line?

This is why the fuel pressure gauge needs to be semi-permanently attached to the Jeep for diagnostic purposes.

 

Here's my update. This afternoon I drove 12 miles. Outside temp was 65*. Went in the store for maybe 10 or 12 minutes. I had HNS when I came out & the only way it finally started was to press the foot feed just a little. Ruff running for about 1/8 of a mile then it leveled out.
Get home & bled the vale & popped the gauge on. Maybe took 3 minutes.

Again I had to lightly press the FF to start. Even ruff the PSI was 39 & 31. (with VH on or off) After it finally leveled out I shut it off & slowly the gauge goes up to 40 & was gradually still creeping higher.

I re-start & let it run for 5 minutes at about 1800 rpm. Trying to really get it good & warm. FP is a steady 31 at idle. When I rev it the pressure drops about 5 psi then jumps up to about 35 to 38. When I release the rev it's a steady 31. Unplug the vac line on the FR & it jumps to 39.

We had a clipper wind & the outside temp is dropping & I didn't want to let anything cool off. I shut down again the PSI starts going up. Within 2 minutes it's up to 40 & creeping. I pull the gauge off of the windshield & close the hood to trap the heat. The TS is reading right at 210.

I wait exactly 8 minutes & have HNS. I don't press the FF to start & so it doesn't. I raise the hood & the PSI is @45. I close the hood & wait 40 minutes.

Open the hood & the gauge is at zero.
I turn the key & she fires right up. Smooth as velvet. I curse & smoke a cigarette.I shutdown & the pressure slowly begins to DROP.

So hot the PSI goes up & stays up & I have HNS. As she cools off the PSI starts dropping & starting is no problem.

I also noticed during all testing of this If I'm standing at the rear bumper after I shutdown, I smell raw gas at bumper level. I don't find a leak & the lines aren't damaged or leaking. To the naked eye anyway.

btw........ya shoulda seen those stumps sailing across the blue sky today.

 

So fuel pressure rises and HNS. Original injectors?

Pressure rising may be normal. Injectors not holding the higher pressure may be the problem. This is jogging some memory cells from the dealership bTW.