Jeep: 1993 YJ 4.0
So I wanted a adjustable FPR, because having the ability to adjust/raise the fuel pressure, opens the doors to a lot more of a selection of fuel injectors to run, where if you still have stock fuel pressure, you have limited choices. It can also help with fine tuning. I did not want to pay the high price for the hesco one. Yea it is drop in and super easy to install, but where is the fun in that? Plus I have a slightly bad taste in my mouth from a past experience with them.
So I set out to find a more cost effective DIY solution. After some looking around, I decide on a FPR from a mid 90's chevy LT1 V8. Stock pressure is 43.5 psi, and aftermarket adjustable models are not hard to find and are reasonably priced. The one I ended up getting was this one:
https://www.summitracing.com/parts/acc-74566
To go a tiny bit off topic, I am running a home brew MPFI fuel injection system on the AMC 401 in my 79 cherokee, and it just so happens I used the exact same adjustable FPR. I have had it on there for around 2-3 years with zero issues.
So now, how do I use this FPR on a jeep fuel rail. Well first, I make a trip to the local pull-a-part junk yard and get a fuel rail from a 96 cherokee. It is the returnless style. I also pick up a fuel rail from a LT1 V8 out of a 95 or 96 caprice. I got the fuel rails for like $5 each. There is a small section of hard line coming out of the LT1 FPR that you will also need, and might as well grab the quick connect fitting from the fuel line as well. Here are a couple pictures of the LT1 fuel rail I just left the stock FPR attached so you can see how it mounts.
Next, I chop the FPR end off the LT1 fuel rail. The inside bore of it has a flat spot, I used a die grinder and make it round. I then tapped it to 3/8 pipe thread. I go to a local hydraulic supply store and pick up two 3/8 pipe to #6 JIC adapters and a elbow. Total cost, $8.
I drill out the end of the cherokee fuel rail that is next to the firewall. I grind down the OD of the threaded portion of one of the adapters and then grind a flat spot in it to make it a snug slip fit into the end of the fuel rail. I then have a friend TIG weld it on.
Modded LT1 fuel rail and the new adjustable FPR:
So for safety's sake, I want to pressure test the fuel rail. I borrow a cap from a co-worker to cap the new #6 JIC fitting on the fuel rail. I then stick some old injectors into it, fill it about 75% full of carb cleaner and using a clamped on air line, pressurize the fuel rail. I was only planning to test to 50 psi, but my finger slipped and it shot to 100 psi! But, no leaks and no blowout at 100 psi, so it should be perfectly safe at normal fuel injection pressures.
So on to installing it. On my YJ, the stock feed and return lines have different size quick connects at the fuel rail. But the actual hard lines are the same size. The stock return line quick connect just happens to be the same size as the feed line on the cherokee fuel rail. So simply remove the stock feed line. There is a quick connect on the frame next to the bellhousing. Now disconnect the return line from the hard line on the frame rail and move it to the feed line. They are both the same size quick connect on the frame mounted hard line. I simply cut the quick connect off the factory feed line that connected to the frame hard line, then got a new section of fuel hose, and using the quick connect saved from the LT1, connected the two together.
I then bolted on the new fuel rail and FPR:
I then ran a new length of vac hose the the new FPR, as the original hose will not reach. I removed the fuel pump relay, and using a jumper wire, turned on the fuel pump to check for leaks while the engine was not running. No leaks were found. I also used this time to adjust the FPR to stock fuel pressure using a fuel pressure gauge that connects to the test port on the fuel rail. I remove the jumper, reinstall the relay, and give it a test. Engine starts and run like normal. I double check for leaks and double check the fuel pressure. All was good. A short test drive and it acts perfectly normal.
All in all, I have a little over $100 in this. Not a huge savings over the hesco unit, but its money I can spend on other things. And in the end, I actually like this setup better. I like how the fuel rail is now "cross flow" Vs the factory style. Now if air or bad fuel get into the fuel rail, it will just get pushed back to the return, instead of being trapped in the fuel rail like the factory setup.
I am not the best at making writeups and my pictures are a little lacking, but hopefully it is good enough to see what I did and how I did it. If anyone has any questions I'll try my best to answer.
