Finally fired the stroker, runs and sounds good, maybe too good because I got in an interesting discussion with a neighbor and then later with a local Sheriff who came by to see "how I was doing".

Anyways engine feels strong, problem is I can't seem to adjust fuel pressure at all, reads a constant 30psi. I'm running a parallel fuel system, stock hard lines to 6AN adapters and stainless 6AN line, (supply and return). Supply goes to a y-block that feeds the end of each rail, (firewall end), and each rail has a 6AN return to the FPR. FPR is an Aeromotive 13101 bypass regulator mounted on the front driver side frame rail, (where ABS used to be). Two lines from the fuel rail output connect to two 10AN-6AN adapters on the FPR and finally fuel is returned to the tank via a 6AN/6AN adapter, 6AN Stainless line to stock hard line. Fuel pump is a Walbro 255, brand new supplied with a Racetronix kit, (the one that comes complete with wiring harness).

A couple of other things of note. Racetronix kit is connected at the battery which is relocated in the trunk. All cable running to the front of the car to a terminal box made with copper bar stock is 2/0 welding cable, overkill but I didn't want any voltage drop. Output at alternator is exactly the same as the voltage measured at the rear of the car, (Battery Terminal) measured with a DVM.

Here are my ideas, let me know if you have any others:

1. Sending unit wiring issue, possibly too low a voltage.
2. Fuel filter, I'm going to check it, not brand new but the lines and fuel filter have been sitting on the floor of the garage for a good while.
3. Charcoal cannister has been removed and the line capped. The only vent for the tank is what came stock, I checked and there is a vent that opens when the tank pressure rises. Wondering if I'll need to uncap the charcoal vent box, possible air in the lines??

I'm betting on something electrical with the gauge. It read zero for a good while when the car was happily idling away. Magically it began working showing about 30lbs of pressure just after I fired the car the second time, but the gauge is showing no change with the vacuum connection removed and running the adjustment from stop to stop. I suppose it's possible that I'm not running any more than 29 or so pounds, which is below the bottom end of the regulator range, (30 to 75psi), but I would doubt it.

 

How bout some love for the fuel pressure question??

 

Why did you rule out the possibility of the FPR being a problem?

 

Thanks for the response. Really I guess just wishful thinking, but the FPR is a brand new Aeromotive unit, but certainly could be faulty. How could I check it?

 

Just to verify, you have the lines coming into the regulator on each side and then the fitting going downward goes to the return, correct?

 

Aeromotive FPR's have been known to fail. About a year ago they had so many problems they came on here and offered anyone with a problem a free replacement, no questions asked.

 

Thanks I'll keep that in mind. I got the thing from Summit and they'd probably send me a new one no questions asked.

 

Update on the problem. Put a mechanical fuel pressure gauge on the system and the problem isn't electrical. I did notice that I'm getting pretty serious "Bleed Down", the pump primes goes to about 30psi which bleeds off completely in about 15 or twenty seconds. Anyways I reason that I'm probably leaking from the hose between the pump and the sending unit fittings, so I drop the tank to inspect the pump. Pump looks fine and I don't see any evidence of leaks in the plastic hose. The regulator vacuum hose is completely dry, so it isn't bleeding back there.

I did find a very small amount of metallic particles in the pump bucket. Very perplexing but I believe that they came from the steel braid line, small fragments of the braid from twisting on the AN fittings.

I guess I could believe that the particles could cause the pump check valve to work improperly, but all of this happened immediately, remember this was an initial start up problem, no fuel has ever run through the system.

I'm going to flush the system by hooking the pump up with the gas tank on the ground and putting the return into a bucket. Then I'm going to remove the injectors and clean them too.

I'm still at a loss to explain the lack of pressure. Pump is a brand new Walbro unit, and I'm running the Racetronix harness. I have another walbro pump, from before beginning the build, I replaced it mainly because it would intermittently shut off and then on a restart attempt you couldn't hear it prime. I've had problem with the fuel system since the day that I installed this kit.

At any rate I'm planning on replacing this pump as well, I don't want to put it back in and have it fail a month down the road because of the metal particles. Maybe I should bite the bullet, sump the tank and use an external pump.

This is very frustrating, I'm ready to put this car back on the road, I've had it down for this build for over a year, an now it's fighting me every step of the way.

 

Is the Aeromotive regulator a 13909 or a 13109?

 

It must be the 13109. I searched the Aeromotive site and there were no results for a 13909. I will be running the 13109 in my car once I get it back together, hopefully within a month.

 

Sorry, that was a typo, it's the 13101 FPR, to 10AN (Inlet), 6AN Outlet. I'm going to bypass the regulator and use the mechanical gauge to get a pressure reading. I don't understand how the regulator could cause a bleed back issue, but of course certainly could effect maximum pressure.

Shouldn't be a problem just priming the pump without any regulator installed, correct. I won't attempt to start it that way.

 

Yes, supply side goes to y-block, which goes to firewall end of the rails, each rail is then connected to the regulator and return goes back to the tank, (bottom 6AN fitting on FPR), via 6AN line.

 

Check to see if the hose from the fuel pump to the hard line is still connected. On 3 seperate occassions the hose slipped off and caused inconsisent fuel pressure along with hard starts.

-B

 

Thanks for the reply. I probably should have updated this thread. Problem turned out to be a bad regulator. As soon as I put the new one in, much more pressure than needed. Brand new Aeromotive regulator too. Summit overnighted a new one and problem solved.

Thanks again.

 

BTW Injuneer I think this was a "subtle" hint that you were giving me here that to which I wished I would have paid more attention to at the time. Yanked the tank with all of the hassle only to find out it was the regulator all along. I guess I have a hard time believing new parts are bad.

Thanks.