Mine screws right on the schrader valve too, but doesn't have anything to depress the schrader valve tip to allow the fuel to pass in order to get a pressure reading. It's not designed like a tire pressure gauge which depresses the schrader valve tip in order to get a pressure reading. The end that screws onto the rail is an open tube.

In order to get a reading, I have to remove the schrader valve to allow the fuel to pass into and pressurize the guage.

Other guys a running the same type gauge and post complaining about the gauge not working. All they do to correct this is remove the schrader valve.

Jake

 

Good post and I think your leson got lost along the way. I agree with you in the fact of not looking at your numbers but rather the fact you did not have a change when you blocked off the line the with the bad FPR, how you blocked it off and what percentage of change you see is kind of irevelent if you know hwta the AFR is when your "normal" FPR is present. Again good post

 

Mine has a pin in it to depress the pin in the schredar valve.

 

Thanks, just trying to share and help.

Jake

 

Okay, since yours has a pin that keeps the schrader valve pin depressed, you don't need to remove the valve.

Jake

 

No, I had to remove the valve because my fuel pressure gauge doesn't have the little pin that can depress the pin in the schrader valve. Without removing the valve I wouldn't get any pressure reading at all.

That's why posted the procedure I used to test mine to help distinguish my procedure from the gauges others might have.

I decided to post on this primarily because I HAD NO IDEA I had a failed FPR. Engine ran fine. I drive the car everyday and recently returned from the Chicago area and didn't have a single problem or indication that the FPR wasn't up to snuff during the thousand mile drive.

Of course I didn't do any WOT blasts during the trip. I bet that would have cause the engine to go lean. Good thing I didn't.

So my thinking was, "Hey, I wonder how many other guys are experiencing the same thing - bad FPRs and not know it? So, let me post what I found so they can check theirs."

Jake

 

Quick question for you, JAKE. When reading the fuel pressure with the engine running, how much variation do you normally see (ie how much does the needle wobble)?

 

Very, very little. I'd say while watching it for a minute or so, the pressure may move less that a psi three or four times. The vast majority of the time it's rock steady.

I don't know if that's normal or not, never seen anything in writing on that point, but that's what mine does.

Jake

 

Hey Jake,

I took your advice and I tried your pliers trick today.

I had to swap out the hard vacuum tube for a rubber hose that I could squeeze off first. I used a six inch length of rubber vacuum hose for the test.

Note: I had previously raised my fuel pressure setting to 54 psi (without vacuum) a year or so ago by using a nickel under the stock regulator lid.

The results were of no surprise to me. The pliers trick didn't work.

All tests were performed with the car idling using a tpis fuel pressure gauge:

Running normally with vacuum applied: 46 psi.
Running w-hose pinched off with pliers: 46 psi.

This was repeated several times.

With vacuum line removed at regulator (open to atmosphere): 54 psi.

My car pulls about 15" of vacuum at idle.

This was exactly the expected behavior.

My regulator is working properly.

It is worth noting that our cars and regulators are different, mine is an L98 with a factory regulator with a nickel under the lid, it looks like you have a MR with an aftermarket regulator, so these differences may explain the differing results.

The pliers trick is not a reliable method for testing the regulator. Instead, simply pull the vacuum line from the regulator and leave the regulator open to atmosphere when testing.

I suspect that your new working regulator is really leaking vacuum. You may want to check it.

 

I have a 86 with a 415 and a Mini-Ram AND a 96 with a 388 LT1. Both have adjustable fuel pressure regulators. The regulators are a different make and design and are not interchangable. The pliars method works just as I posted on both engines exactly the same way.

If it hadn't worked as I posted, I wouldn't have posted as I did and I would have taken the new Borg Warner adjustable FPR back to O'Reilly's where I bought it for a refund. Why would I keep a FPR that acted no differently than the stock one I removed??

I didn't and don't have a hard vacuum line feeding the regulator and the regulator has a dedicated vacuum line, not 'T'd off. In other words, there is nothing else feeding off the vacuum hose that connects to the regulator. It's a single hose that runs from the intake to the regulator with nothing else attached to it.

I attach the fuel pressure gauge to the schrader valve location with the valve removed.

Just to put this to rest once and for all, I'd like someone who's near Dallas to come by and I'll demonstrate it on both cars. I'll even buy lunch.

I live at 500 Rolling Hills Place, Lancaster, TX, just south of Dallas right off I35E.

If no one takes me up on that offer, I'll take pictures and post the results. This thing seems to have taken on a life of its own.

BTW, there's a very noticable difference in engine performance with the new regulator. Hard to explain, but the engine is quieter, smoother, pulls harder, more responsive and even the exhaust temp leaving the muffler tips on the LT1 is not as hot as before.

Jake