Hey all,
I'm stumped. This is on an 86 Iroc with a 383, holley ecu, and stealth ram set up. I have a Kirban adjustable fuel pressure regulator put on its usual spot. New sending unit in tank, with Aeromotive pump. The steel braided line set up everyone uses from the steel lines to fuel rails. Lines in correct spots.

Ok, my problem is when I prime the pump, my gauge says I have 71lbs. As soon as.the pump stops priming, it falls to 10. When I try to adjust it down via the regulator, it does not change the presuure one bit. Even tried to go up, no difference. Checked all the lines for.proper placement. Made sure nothing is binding or pinched on the return line. Had a fuel pressure gauge going to the Holley ecu, and it said 69 lbs of pressure before i shut the pump off mid prime due to a.leak at the sending unit connection. (I took off ecu sensor too because of leak). Fixed all of that, no leaks, but still high pressure and no adjustment on brand new kirban.

Any ideas, is the Kirban bad? Is there a way to check it? Or do I need to buy another fpr to tell. I'm at a loss here and I don't want to just throw money at a regulator if it's probably something else. Thanks in advance.

 

If two gauges are indicating 69 and 71 PSI, the return line is unrestricted and intact, and the regulator doesn't adjust, it would seem that the regulator has a problem. If it is under warranty, replace it. If not, open the case and see just how badly damaged/obstructed it is.

 

That’s a really old not available fpr. I don’t think there is even a diaphragm replacement for it. Modifying the rail for a external aeromotive would be a good fix over holley replacement if there New one even mounts to the old rail.

 

Just ordered it maybe 2 years ago (although it took about 3 months to get) only was making them still in small batches? Didn't know they were no longer available. Definitely didn't want Holleys. I thought Aeromotive made.one also that would directly fit to the rail too? Is there any left that anyone knows about that would fit to the rail, dont really want to modify if I don't have to and realestate is hard to come by for external mounting since I still have everything. What gets me too is the pressure dropping the.second the pump stops priming. If there was a restriction any where on the return, you would think it wouldnt drop immediately. Has to be this 130 dollar never used fishing weight then. Nice.

 

Maybe I’m wrong worth a phone call

 

Ok, a little deeper dive shows avaible regulators:
Holley- non-adjustable rail install (512-515)
Kirban- adjustable (6547)
Accufab- (Buick GN 1986-1987) product code: BREG
These are all still available if anyone needs one.
As far as my issue, I plan on breaking the return line right after the regulator (braided line is only like 36 inches at most) and running it into a gas can. Verify my pressure is still high when I prime, then I know it's the regulator. Swap out for new and done. If not, I do own a.lighter, lol.

 

Great part number find

 

One more thought on this subject. Does anyone know the actual order that the sending units lines are in (outside of the tank)? I ask because on the 4 lines coming out, starting with the feed line (threaded) mine are hooked up:
Feed line
Next would be return line
then charcoal vent line
Finally tank vent
I know i can't mess up the feed line, but the return goes to the bottom of the sending unit, where the other 2 open up at the top lid on the sending unit, all connected by rubber hoses. That wouldn't make a restriction in the return would it, if something was switched? Maybe enough tank pressure to not let it drain properly? Just a thought as I try to figure this out with the least fuel spilling. Is my order correct, cause now I'm second guessing.

 

OK, just thought I would update this, in case someone else has the same issue. When i put the new sending unit in, I just matched up the lines from the unit, to the lines on the car in order that they were coming out of the tank. This was not correct. The first was the feed line so no problem there since its threaded to threaded. Next 3 was for the return, charcoal vent, and tank check valve which are all rubber.
I had the charcoal vent and return rubber lines swapped. When I swapped them back, i had no pressure regulator issues, other than having to set it at the correct pressure. So lesson learned, if the regulators pressure is high and you cant adjust it no matter what, you either have a restriction somewhere in the line, or the lines crossed.

 

Thanks for reporting your results. It seems that you performed the thorough assessment of the system and discovered the problem. Onward toward tuning the stroker.