I am planning on gutting the internals of the stem, but leaving the outer section of the stem, as it keeps the filter centered and makes sure only filtered fuel is headed out. You are right on the guts of it though, it is simply there to prevent it being ran without a filter. I would be interested to see if somewhere it mentions lining those windows up. I guess it is kind of common sense, but at the same time, not everybody will realize it I'm sure.

One of the first things we tried was sending units and gauges, I was kinda bummed it didn't turn out to be something easy like that. All in all it was a cheap fix though too. Rich had a stock FPR to put on there and everything else, I only ended up buying a couple short bolts and some fitting caps because we couldn't get the one FRx fitting out of the head. Unfortunately I also put a new pump on so that added a bit to the cost, but on the bring side, I have a new pump.

Baatzy

 

I need to write this down before I forget......

First thing we did was take a known good sending unit out of my Excursion and put it in Baatzy's truck. We were thinking this was going to be the issue - but we go the same exact readings with my sending unit....

EDIT: we also installed a manual FP gauge on the drivers side port to verify all the readings from the electrical gauge. The ISSPRO gauge was spot on with the mechanical gauge during all our testing.

65-ish psi with KOEO, once the glow plugs went off she would climb to 80 psi and the bowl/filter cap would leak.


oh well, we decided - lets check out the gauge and get some voltage readings. So we first checked the power voltage to the gauge and she held steady at battery voltage. Then the sensor checked out good as well. IIRC 4.5V from the sensor = 100 psi. 2.5V = 50 psi and .5V = 0 psi.

Just to make sure - we took the gauge out of my truck and put it in his. Same readings........damn

 

Time to dig deeper.

We just couldn't wrap our head around the pressure drop he was experiencing during acceleration and the high PSI readings at idle.

Then we noticed that the pressure would fluctuate depending on voltage, something ExPACamper brought up.

We noticed that with the alternator on and the voltage up at 13.7 or so after the glow plugs were off - the PSI would climb to 80. But with battery voltage only, we only would see 65 psi (approx). So Baatzy took her for a ride with the alternator disconnected just to see what she read. IIRC, the Fuel Pressure didn't go up higher than 65ish, but she still would loose pressure ( down to 40) during acceleration. Baatzy, correct me if I'm wrong - it was a few days ago.......

 

Then we decided to just take off the FRx and put it back to stock. Just easier to troubleshoot when it is stock and no extras. So we fought the darn fittings Baatzy's cousin torqued to gorilla setting ......Got the FRx off and the FP reguator returned to stock. Had to make a run to Ace Hardware to get some new bolts (what size were the Baatzy??) since the ones that came with the FXr were too long for the stock FPR housing.

We got the fuel bowl back to stock and fired her up. The Fuel pressure didn't climb past 58 or so. We were happy about that. But what we did notice was a squeal from the fuel bowl while we were priming her up with the KOEO. So we took of the filter to take a peak and that was when we noticed the window in the Fuel Filter Check Valve Assembly wasn't lined up and causing a restriction in flow. Rocky (Rockin S Performance) showed me that a few years ago, since then I gut the insides of the assembly since I'm not gonna forget to put a fuel filter in there and it can be a restriction in the higher HP tunes.

After we got the window turned in the check valve assembly and the stock FPR back on all was good in the world again. We are not exactly sure what was causing the high pressure readings, but when you read Riffraff's instructions it does say that higher pressures can result from incorrectly installing the spring. We could't see anything that was wrong when we took the spring & housing off. The next step - I think is to install the FRx again with the stock spring and see what happens. The low pressure must have been from the restriction in the check valve assembly.

 

You guys are doing some great work! Let us know what you find with the FRx

 

It would not go above 65 psi with the alternator disconnected, except when I would let off, it would bump up slightly. Also, the bolts for the FPR are M5 x 0.8. I believe 16mm long is the length we finally settled on as the closest correct length.

Eventually I am going to reinstall the FRx, but I need to get new head-to-line fittings first, and would like to get another set of springs to try.

So far the stock setup has been working well, #8 is a little louder but it sounded like it was running better than before, so I'm not sure what to make of that.

Baatzy

 

As you've seen on my current thread, I'm tinkering with a similar problem, but pretty sure it is all related to poppet and spring action.

I had help with the major work last spring and an afternoon turned into a couple of days, finishing up the DAY BEFORE leaving for almost 2 weeks with the camper. Long days, late nights.

No complaints, my buddies were awesome and I appreciate all the help. But they installed the FRx while I was dealing with the 4/4 with bad threads, so I didn't know what all was involved or done there

After pulling my FRx regulator off the bowl yesterday and seeing how little room there is with the lines and EOT sensor, I'm willing to bet that FRx/spring misalignment is more common than we think.

I'm going to dig into her again today, removing the lower line, too, and see what I can accomplish.

My gold spring may be damaged and the others were lost during the install, so there's that possibility, too.

I'm wondering if there is something about the inside structure of the FRx FPR on the spring side that I'm missing?

Maybe there is a tit or something it should sit on? Something that would prevent the "slip it into place" method I used from allowing it to seat properly

I didn't have very good visibility yesterday, which I will correct for today.

Do you have your FRx handy?

If so, can you take a pic of the spring side of the regulator, showing the inside of it? What bumps, grooves, ****, whatever are inside it?

 

This is what I have. Hope it helps.

 

Excellent pics, thanks!

Notice the double-step in the FPR in the last pic? Think that's what I missed.

At least that's the hope. I hope I didn't damage/stretch the spring

 

Scotttahoe,

What pressure are you seeing?

 

I'm seeing 70psi on my gauge with the gold spring at idle.