Aeromotive FPR ?
 

Hello Rotaryfreinds,

I have just installed the RX7 store fuelsystem, with new secondary fuelrail and BOSH 1680 cc injectors (I have keept the primary stock) the system came with the Aeromotive FPR and when I pressuriced the system to look for leaks etc. at first the gauge showed about 38psi dropping very slowly to about 30 and apparently stayed there, then I thougt maybe there was a little air in the system, so I pressuriced it quickly to 38 psi once again, but then when I shot off the ignition it dropped slowly all the way to 0 psi ! I did it again and the gauge shows 38 psi when ignition on, but now when I shut ignition off, the pressure imidiately drops to 0 on the gauge ? can anyone tell me if I have done something wrong and what to look for ? I can not see, hear, smell any leaks by the fuellines, FPR, fuelrails etc. so why can't it hold pressure ? where could the pressure go ? I have hooked the system up like stock, in series, with stock fuelline going to the secondary and stock returnline going to the buttom of the FPR ! hope anyone can help me ;-) thank's in advance.

Rene
DENMARK

Make sure the small vacuum port nipple screw isn't screwed into the hole too far. If its screwed in too far it can contact the diaphragm spring and lock it into position. Try backing the nipple out some and see if it cures your problem.

Aftermarket regulators like the Aeromotive are not intended to hold pressure once the pump is off.. but they do usually hold some residual pressure for quite a while anyway... so your immediate drop to zero would usually indicate a pressure leak somewhere.

If you have no external leaks, the fuel pump hose in the tank could be leaking, or the check valve in the fuel pump could be dysfunctional. Less likely, but you could have a sticky injector as well.

Hello guys, thanks for your reply ;-) I have now plugged off the return line on the FPR to see if it was a leak in the fuel rails/injectors but luckily this was not the case, it now holds pressure for quite a while, but still drops very very slowly, but as I can read this is pretty normal with the aeromotive FPR ? Anyway, as soon as I connect the return line to the FPR the pressure drops quickly again ! So this tells me I have a leaky fuel pump or something else ? Any good solutions to pressure test the fuel pump, check valve etc. ? Thanks in advance :-)

Rene
Denmark

Mine goes 38psi while running, turn it off and it drops to 20psi then slowly falls over a few mins

Given there are no leaks and car drives normal, it's OK, mine does the same.

Back in the day I called the Aeromotive tech line about this very same issue. Was told that it is perfectly normal. Apparently holding pressure for 20 minutes is just an emissions compliance.

Yes holding pressure like OEM regulators is a cleaner and faster engine start which people are used to these days. My brand new mustang primes the pump the second you touch the clutch pedal.

To the OP, it sounds like you have determined that your regulator is dropping system pressure quickly through the return outlet. This is the only place the regulator is able to loose pressure to... so I would expect pressure to hold very well with the return line capped off.

Again, these regulators are not supposed to hold full pressure for a long time. But they dont usually go to immediate zero with the engine off either. If it does, I would suspect that a containment could possibly be inside the regulator, stopping the valve from fully seating and holding pressure to the best of its ability. However, if its not causing a problem, I dont think I would chase it.

https://www.rx7club.com/3rd-generati...ssure-1033578/

I made a thread about adjustment a while back. Didn't really care about the pressure after the car was off.

Hi guys ;-)

Thank's again ! yes with the returnline plugged off, the pressure will hold for quite a time, but still drops slowly, but this is pretty normal I can understand :-) I am deffinately sure now, that I do not have a leak in the fuelinjectors, fuelrail etc. I took out the sparkplugs to see if any fuel had leaked into the motor/chambers, but this is not the case, so it has to be in the returnline, fuelpump or checkvalve I guess ? or could it still be inside the FPR where the little ball is ? I guess I can take it apart to inspect/clean it inside ?

Rene
DENMARK

Hello again rotary friends,

Just giving you guys an update. As mentioned, I would take the FPR apart to see if any dirt/debris had hung up at the ball valve in the FPR ! and guess what, there was dirt/debris on that ball valve ! I guess it must have been from the new fuellines, that I must admit I forgot to rinse, blowing air through it, before installation. So this must be VERY important to do before installation of new fuelinjectors, fuelrails, fuelhoses, FPR etc. ;-) anyway, I cleaned the hoses and the FPR and blew it with an airgun and now it holds pressure as it should, with the returnline on :-) the pressure still drops after shutting off the fuelpump, but only slowly from 38 psi to 20 psi and then it holds pressure for hours before down to 0, and this is what everyone says the aeromotive FPR does/should do, even aeromotive them self write it in the installationinstructions (I had not see that at first) that it is not designed to hold pressure for very long periods, like the OEM FPR !

Thank's again guys.

Rene
DENMARK