I got an aremotive eliminator fuel pump. Still red in color, same size just more volume than the AE1000. In second year with this & no problems yet.

Ok, I have been working with procharger on my problem also. Same red regulator as shown above. I have twins, one motor works great, 30 lbs idle 55 wot, the other motor is 30 lbs idle and 50 lbs wot, even if I set it at 40 lbs idle it is still 50 lbs wot. I agree they are not the same, sometimes they are 38 lbs at an idle other times 30, however in my case it is alway on the high side which is ok. I also see a fluctuation on my "bad" motor by 4-5 lbs about every 15 seconds when at an idle on a mechanicle gauge, it will bounce from 35 to 30 and right back to 35. I was starting to think I have a bad pump until reading this post. Now I wonder about the regulator. I may swap mine between motors and see what happens. Maybe I have a bad one also. I have had great help from PC so far, if it all who you talk to, I think there is only one support guy that is good on the marine side.

You may also have a stock regulator problem if you have the cool fuel system, PC has a kit to eliminate the stock regulator from the circuit.

Anyone know why the fuel pressure would bounce 4-5 lbs in a second at idle? Is this a fuel pump problem or a regulator issue?

tssteph, for you to never get over 50psi I am going to say fuel pump or it could be just filters.

I was wondering if the regulator was not working correctly it would never hold back more fuel.
My past experience with cars is either an electric pumps works or doesn't.
I will swap regulators from one motor to the other and see if the problem follows. Since the pressure is eractic at an idle I can check oh the hose.

One way to is to clamp off the return line & then see what the max pressure that the pump will build

Gpm,i looked at the weldon pump,it looks impressive. How well does their regulator boost reference? This time on dyno Crockett set up motor with 40 psi base pressure and we boost reference the presure up to about 70-75 psi,some regulators only raise pressure 1 psi for every 1lb boost but i need one that is adjustable for about 3.5psi-4psi per lb boost,Thanks for any info,Smitty

How much pressure are you running for base pressure,how much under boost,how big of injectors and what kinda hp are you making,thanks,Smitty

The regulator is 1 to 1, you should be running at least 43.5lbs at idle, that's where the injectors are rated. Why are you running 75lbs at top end, are your injectors to small?

GPM, I was wondering same question about why 70 psi, but if I remember correctly with the intake he is using there is a problem in putting in bigger injectors.

As to what I have, 96lbs injectors, aprox +/- 1000 hp (never dynoed) With the areomotive regulator when it is boost refrenced the presssure goes up & down with vacuum or pressure so I set at 43lbs with engine off. Once started pressure goes down below 43, as boost come on it goes up 1 for 1, so at 10 lbs of boost running 53 lbs of pressure. If you are going to run 70 lbs of pressure you are going to need one hell of a pump to give you enough fuel for 900+ HP. If you look at areomotives web site they say the eliminator pump is good for 1600 HP - Naturally Aspirated & 1100 HP - forced air induction all because the pump will not pump as much fuel at the higher pressures.

Gpm,i'm running 63lb injectors ,they are largest ones that are high impedance and can be fired by mefi-3. I could have used bigger injectors if i spent another 2000$ plus dollars on a fast stand alone computer or similar. So I am still stuck with boost referencing the fuel regulator under boost which brings up the problem at hand,if i buy too big of a fuel pump my regulators i'm using won't return enough fuel and will cause my off boost fuel presure to go too high. On dyno we used a magnaflow carburated style fuel pump (500gph) to feed my essex pump and had 70-75psi under boost. The regulators that will handle big excess flow from big output pumps usually have a 1-1 boost reference which won't work with my EFI program. I will probably have to install a booster pump on a msd window switch to come in at 4000 rpms when i really start using the most fuel. Right now I'm researching what my options are while i wait for my tailpipes to show up for boat.Smitty