Fuel Pressure Regulator

Flyer58

Flyer58

YJ Enthusiast
Joined
Apr 12, 2020
Messages
937
Location
Magnolia, Texas
Where can I find a fuel pressure regulator with the proper 31 PSI control?

Yesterday I had a stupidity problem with my 2.4L MPI losing power and going into what modern cars do which is Limp Mode - not a YJ feature but that's what it seemed like and as I pulled into the driveway I barely had 25% normal power. It was relatively smooth, just no power. This happened shortly after checking out some local area flooding and driving down a road with about 6-8 inches of water and a strong current crossing the pavement. Glad I didn't get stuck.

So today I started troubleshooting by checking the plug wires and fuel pressure. In the end I found the one problem is the regulator keeps a steady 31 PSI with vacuum but never increases 8-10 PSI when the vacuum source is removed. I haven't checked the vacuum with a gauge yet but feel a good suction at idle with my fingertip. The vacuum lines and connectors look good. Pressure leak down test is ok for about 15 minutes.

31 PSI is where it needs to be under normal conditions but I don't feel like it works all the time.

I checked the internet, Amazon, big boxes, and they all offer one that fits but they say it's regulated to 41 PSI (or no info) and the complaints from YJ owners are they now get 140 miles per tank where they got 240 miles in the past. So the higher pressure isn't working.

Any idea where to find the proper one?

Now, to make a long story longer... My YJ fuel float still isn't working properly because the float is flooded and sinks so I always reset my trip odometer and fill the tank every 200 miles after the 20 gallon mod.

Well come to find out, as I was checking the fuel pressure I was getting erratic results at first so I wanted to flush the fuel rail by connecting a hose to the schrader valve port and turning on the key or jumping the fuel pump relay. Less than 1/2 a cup of gas came out then nothing. Rechecked and still nothing.

This should not happen because I was only 140 miles into a full tank yet all the pump was doing was pushing air.

Problem solved after I put four gallons of gas in the tank, primed the system, and now all is normal again. Runs smooth with power. Glad I made it home with 1/2 cup of fuel in the tank and didn't get stuck in the middle of the river.

So this brings me back to the fuel pressure regulator. Maybe at times it's exceeding the 31 PSI and cutting my range down to 140 miles/tank.

I want a 31 PSI regulator just to eliminate any more guessing.

Cheers
 
quadratec has 3 listed, didnt see what yr wrangler you are puting on. . they start at 60.00/80.00/260.00. good luck
 
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I seem to remember going to O’reillies to pick a regulator for a carb conversion and was adjustable one. Been a few years ago.going back to the store tomorrow or Thursday and can see if I pulls up again. I looked for the one that I picked up but it is lost somewhere in the garage of chaos ! I’ll look again tomorrow. If I have one I’ll send it to you. I decided to stay with TBI.

Dave
 
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Thanks so, I'll see what I can find here. Yes the pressure range is 31 -39 depending on vacuum. Mine seems to be stuck at 31 with or without vacuum which might be OK. I'm going to fill the tank today and do a MPG test. I'll let you know what I find.
 
have you put a fuel pressure tester on the line. i went back and reread your problem and i was wondering when did you last done a tune-up, right plug,gap timing , that vehicle should be getting more than 10 miles to gallon if it close to stock. lets us know .thanks
 
dieselearl said:
have you put a fuel pressure tester on the line. i went back and reread your problem and i was wondering when did you last done a tune-up, right plug,gap timing , that vehicle should be getting more than 10 miles to gallon if it close to stock. lets us know .thanks
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I'll keep updating this. The plugs, wires, cap, and throttle body are either new or cleaned about 1000 miles ago during a full engine rebuild. The only original items are the injectors, fuel pump and pressure regulator. Timing was checked ok but it's controlled by the ECP si there's nothing I can do to adjust it. The odometer has close to 100,000 miles on it which I think is accurate.
 
Update, I think all is good for now regarding the fuel pressure, or good as it can get using older Harbor Freight fuel pressure test kit.

I went on a short drive and with a warm engine the running fuel pressure was 32 psi with the vacuum attached and the pressure was 40 psi with the vacuum disconnected.

I did a 30 minute leak down test and found it's right at the limit of 11 psi.

Here's what the FSM says:
Allow engine to set for 30 minutes and
then compare the fuel pressure reading on the gauge
with the reading taken when engine was shut down.
A pressure drop of up to 138 kPa (20 psi) within 30
minutes is within specifications.

1715218083378.png


I'm calling it good for now and will do another MPG test soon. Maybe run it for 100 miles on a full tank and see how much it needs. I was getting about 14mpg with the 31's tires, AX-5 and OEM differentials.

I don't know what to say other than I didn't fill it up all the way last time.

Cheers and thanks for the help.
 
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Be sure to tighten all manifold bolts to spec. Mine were really loose and after tightening them my mpg is great…for a yj. Some people find the rear one is totally missing.
 
redbullet said:
Be sure to tighten all manifold bolts to spec. Mine were really loose and after tightening them my mpg is great…for a yj. Some people find the rear one is totally missing.
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I'll check for leaks. The first front bolt/stud was snapped off on mine and had it fixed when the head was redone at the shop. Seems to be a common problem.

Something else that different from the way the factory did business was the exhaust manifold went straight on the head with no gasket. The OEM gasket was only for the intake manifold ports. When I reassembled everything I used the recommended gasket which covered both intake and exhaust ports. it worked ok but one thing to watch out for is now the exhaust flange sits one mm higher than the intake flange. If you don't use the proper curved washers you may get an intake leak due to the manifold not being securely clamped tight.
 
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Ha,well heck. Full tank of gas but now my trip odometer doesn't reset. Push the button and nothing. Worked for the last few years so I don't know what to say. I think it may be a sealed case so I can't get to the internal parts.

On a positive note my new windshield wiper blades fit.
 
youtube has video on how to fix. does speed 0 and odometer still work, it not it probably the speed sensor on tranfer case. i am told that people with SMART phone has a appl on google that you can use, works the same way as your vehicle. good luck
 
dieselearl said:
youtube has video on how to fix. does speed 0 and odometer still work, it not it probably the speed sensor on tranfer case. i am told that people with SMART phone has a appl on google that you can use, works the same way as your vehicle. good luck
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Thanks, the speedometer, odometer and trip all work but I just couldn't reset the trip. I found a video about repairing the trip and it's pretty straight forward.

After watching the video it brought back memories of removing the clear plastic face cover to clean it when I had the gauge cluster out.

After driving about 14 miles today I just poked the reset button several times and all the trip tumblers reset to zero.

My guess is it needs a little cleaning and light lube.

Thanks again.
 
Flyer58 said:
Ha,well heck. Full tank of gas but now my trip odometer doesn't reset. Push the button and nothing. Worked for the last few years so I don't know what to say. I think it may be a sealed case so I can't get to the internal parts.

On a positive note my new windshield wiper blades fit.
Click to expand...
Happened to me before…I pushed the reset about five times in a row while moving and was able to reset it
 
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