Ok, so there are a couple issues that i don't think are related but both are driving me nuts.

So first thing that i don't have a lot of info on is boost pressure. I've been tuning this new engine and slowly upping the boost. I'm using the haltech boost controller with a mac solenoid. I'm doing standard duty cycle control.

So for the last week i've had it set on duty cycles that have been giving me a solid 16psi +/- a small amount here and there as i move through the rpm range.

2 nights ago i was doing some pulls and doing some a/f adjustments. After i did some adjustments i went back out and did 3 pulls all of which the boost was solid at 14.5 psi. No boost controller adjustments at all. I was really confused so i put it away for the night. Yesterday before i took it out i was checking the exhaust and found a slight leak at one of my downpipes. Ok, so this was my boost issue i guess. Well i went out and did some pulls anyways just to see and low and behold the boost is back up to 16psi again. The map wasn't touched from the day before. So the boost leak was in fact not the issue with it.

so, what else could have caused this? Is there a possibility the solenoid is dying or was this just a fluke with the solenoid? Other than a dying solenoid i have no idea what this could be.


Next problem: fuel pressure. I've been having this problem ever since i installed my CJM stage 3 with twinpump. I have hks 1000cc injectors and i'm running pumpgas. I have the idle fuel pressure set to right at 40-41 psi with vac reference. i was using a T off of the evap line for vac reference and i assumed this might have caused problems so yesterday i drilled and tapped my own source for my FPR vac source on the plenum. Well the problem didn't change.

So when i start the car and after it's done warming up it idles nicely at 40-41 psi of fuel pressure and i'm at -14.5 to -15.0 inHG in the haltech for my vac at idle. 1050 rpms.

So i go and do a few pulls and then as i'm idling and adjusting the fuel map i noticed that my idle fuel corrections are adding crazy amounts of fuel. I checked the fuel pressure and it's down to 36psi. Well that's the issue. I didn't change anything and just let it be. Later the fuel pressure was down to 32psi. The idle was still the same around -14.5 and 1050 rpms so it shouldn't have been seeing more vac to cause a drop in fuel pressure. So i cruised around for a while then when i got back to the garage i checked it again and it was back up to 41psi.

The car has a half tank of fuel which is normally what i keep in it so that didn't change either. A year ago i had a diaphragm in the FPR fail on me and fall into pieces. I replaced that with a new aeromotive diaphragm. I don't think it has failed again because when it failed the first time the a/f went extremely rich and the fuel pressure went through the roof. Completely different symptoms.

So, vac is the same, idle is the same, didn't change anything and my idle fuel pressure changes. Some of the things i'm thinking: bad spring in the FPR and it gets soft when the fuel heats up from use, possibly 1 of my walbros is going bad in the setup (but i'm not getting any issues of lean with my boost pulls so that kind of rules the fuel pump problem out), or maybe i have the idle fuel pressure too low. The FPR says 40-75psi so i'm curious if that means before or after vac reference. Maybe at 41psi i'm right at the low end so the spring is right at the edge of not working properly.

additional info: i forgot to add. i have a 4 gauge wire run back from the battery to a splitter box and about a foot of 12 gauge wire runs to each of my pumps. My ground wire is about a foot long as well and it's 12 gauge. My voltage in the logs is always from 13.8-14.0 volts. With that setup i'm pretty confident it's not a voltage loss at the pumps. They also wouldn't have too much draw since we are dealing with a problem at idle.

I've tried to do anything i can do to repeat the situation and it seems like there is no 1 set thing like as the car is run longer the fuel pressure consistently drops down to 36 every time. No, sometimes it does, sometimes it doesn't.

thoughts on what it could be? My next test is to take off my vac reference on the FPR and drive it around and see if i can get the pressure to lower like that. The only bad thing is since i won't have boost reference i don't want to make any pulls without adjusting my fuel map (lower pressure will make it lean). If it still does it with no reference the i know it's not the vac reference causing it (which i don't think it is).

Thanks for any suggestions you can offer.

 

the return hole in the FPR is soo small, that even with the adjstment screw all the way out, ~36psi is as low as you can go.

just pull the 4 bolts off the FPR and check the diaphragm. if its bad, and is leaking, that will def cause your issue. Obviously you dont have any leaks around injectors killing the pressure, as you'd def smell/hear/see that.

have you tried tuning your BCS with closed loop? That way you can see if the BCS is adding more or less duty to hit the 16psi target. Temp/baro changes will effect boost levels with an open loop duty cycle only control.

But you said you were at 14 psi, tightened the downpipe and went back to 16psi. So its all fixed now?

 

so a couple updates and i'll address your suggestions:

so i took the car out. First fired it up and let it warm up. at full operating temperature it was idling at 41psi. I drove it to sam's club to get some groceries. At sams club it was now at 38psi. I went in a shopped, took about an hour. Fired the car up in the parking lot to leave and checked the fuel pressure. It read 30psi on the dot and my fuel correction was at full positive correction at idle. At all these times my vacuum on the engine was exactly the same. Got the car home and the fuel pressure is back up to 38psi.

Rich, i have it set on 12psi closed loop right now but i'm not sure what to log to check what you asked.

With open loop i'm aware that baro and temp changes will affect the boost with a set duty cycle. The thing is i did 2 pulls at 16psi (which it was set to all week) then 10 minutes later i did 3 pulls which were all at 14.5 psi boost. Baro and temp won't change it that much in that short of a time frame so i'm not sure that was the issue here.

Now that it's back to normal (16psi of boost) i have not changed anything. I didn't tighten the bolts on the downpipe or anything...it just went back up to 16psi.

 

ahh ok, hmm, not sure about the boost then. unless your BOV is sticking and not closing all the way all the time

unless a pump is going, its gotta be the FPR. that or your gauge sender is bad. turn off closed loop fueling and verfiy that your AFR is really changing.

i thought there was a log for duty cycle on the BCS. I was thinking that way you can verify that the BCS is working if your log an increase in duty cycle and the boost actually goes up when its trying to target 16psi. if the duty cycle is rising but the boost isnt moving, then you can start troubleshooting from there.

but if its at 16psi again and you arent seeing that issue, prolly cant do much until it happens again.

 

sweet, i added boost duty cycle to my auto log. we'll see what that does if i ever have an issue again.

The gauge i'm looking at for the fuel pressure is mounted directly to the FPR so i don't think the gauge is bad but i guess it could be. I'll turn off closed loop and see how much of an a/f swing i see when the fuel pressure drops.

I never thought about the BOV leaking. It's a TiAl 50mm and only a year old but i guess anything is possible.


I wonder if i can get a FPR from a friend and throw it in there to see if it continues to happen. I'll ask around and try to find one. I don't really want to shell out 130$ for a new regulator to just test.

thanks for the tips...i'll start checking things out tonight and tomorrow morning.

 

when the fuel pressure is at its highest when idle, which seems to be about 41 for where you have it set. at that very moment see if you can adjust it to go lower than 41, or if 41 is the lowest it will even go. if you cannot lower it beyond 41 at the moment it would be there with current setting, then i would believe there is an outside factor regulating pressure and that the regulator is actually set lower than 41.

in that case i would check the return fuel filter/diffuser in the twin pump for anything clogging it up, perhaps old pieces of regulator diagrahm.

this could also be tested by noting if fuel pressure actually climbs past 41 as soon as you go into boost. if it doesnt climb immediately into boost, then it is actually set lower.

otherwise, this regulator might just be plain bad. fuel pressure is only regulated by the regulator, or any restrictions preventing it from doing its job.

 

I'll open up the pump again and see if more of that diaphragm has clogged the diffuser. That thought did cross my mind briefly.

When it's at it's highest, 41psi, if i pinch the vac hose off the pressure immediately rises to about 46-48psi line.

 

when my diffuser clogged i couldnt get it below 50 or 60psi.

so unless its not that clogged, thats prolly not it, but worth the 2 minutes it takes to check.

 

Ya, possibly one chunk stuck in there holding it at 41psi until it circulates enough to dislodge and drop the pressure.

 

I've heard of people running without the diffuser with no problems. We only put it there because there is just so much return fuel volume if both pumps are running at idle, I was worried about it blasting in with too much velocity. Since it didn't restrict enough to back up the regulator I figured might as well just in case. Honestly never crossed my mind about gunk clogging it up. If the pumps are staged anyway then I'd say ditch it if you want.

The last thing I would try, if when the pressure is going on the low end, if you can raise it back up at the regulator and it behaves normal at that temporary setting... It's gotta be the regulator.

 

They aren't staged yet Charles but I have been thinking about staging them.

I'll see what the diffuser looks like and if its clear of gunk then ill try raising the pressure to see if that makes the issue go away

 

ok, updates for today.

I pulled apart the twin pump and checked the diffuser for clogs. It looked clean to me but i removed it and blew it out with compressed air just in case.

Pulled apart the FPR and everything looked great in there. No weird wear on the diaphragm and visually no holes or tears.

I re-assembled everything and fired the car up. At idle i adjusted the fuel pressure to 42psi. When I take away vac reference it goes to 50psi.

I then was checking the fuel pumps and listening when i decided to move the relay to the fuel pumps. It was hot enough it burned my hand. I only used a single 40amp relay for both fuel pumps to simplify the install. The walbros shouldn't pull a lot of amps but the fact that the relay is heating up so much makes me think that the fuel pumps might be drawing enough current to heat up the relay to the point that resistance at the relay is increased which would reduce current flow to my pumps.

While i was messing around i decided to check fuel pressure with just 1 pump running at a time. I checked each pump separately and they each produced 38psi of pressure so only a 4psi pressure by disconnecting a pump.

So, right now my only theory lies in the relay theory. Anyone else think that this could be the main issue? I have small sections of 14g wire running from the distribution block to the relay and relay to the fuel pump. I think for the short amount of wire that should be sufficient in size. I couldn't fit the 12g wires into the twinpump connector so i had to move to a smaller size.

It appears that the most current draw i have seen from someone testing a 255 walbro is 11.5 amps at 73psi of fuel pressure. Doesn't seem like the 23amps total would harm my 40amp relay but then again maybe it is.

 

Ok, so i kept just 1 pump hooked up:

1 pump running: now 42psi (earlier today it was 38psi with a single pump)

went to radio shack and got 60amp relay. When i came out I swapped the relays and checked fuel pressure. Now it's down to 30psi.

Drove home, checked it when i got home: back up to 42psi still on a single pump.

I'm now officially going crazy. Anyone have an aeromotive FPR i can use to swap out. I'm not sure what else can go wrong with a simple FPR but something has to be going on with it. Maybe the spring is crappy and has fluctuations?

 

weird. i almost think its your sender. i dont think I could ever get 30psi even with the FPR wide open. did you check your AFR with 30psi?

 

ya, it had max fuel correction (+15%) and it was idling at 16:1 a/f so it was definitely lean.

what sender? you talking about fuel pressure sender? The gauge is mounted directly to the FPR so no sending unit on it. I just get out and check it while it's sitting there idling.

 

ahh, i was think you have an electronic FP gauge. so you really have no idea besides AFR what your FP is doing while you are driving?

any new developments?

 

Sorry been out of pocket Jeff - reading this late. When you looked at the wiring around the relay was there any oxide coating (green or white) that you noticed? I would double check to see if the insulation around your wiring to the pumps looks melted.

Occasionally I need to replace wiring going to my radiator fans. I cut out segments and patch in new segments (and have gradually gone from some crimp connections to all soldered connections) - the internals slowly get covered with an oxide coating. It's weird but may be a symptom of heavy constant current draw.

If it's not a big hassle, you may want to run new wiring from the battery to the pumps and just test to see if it fixes the issue. Actually just use spare low gauge wiring to extend the leads for your multimeter and measure the resistance for positive and negative going to your battery (after disconnecting the battery!).

Unfortunately if the relay is hot, I have a feeling you have one pump that is drawing too much current and may be failing. Did you try to alternate between the two pumps (running alone), and see if pressure jumped back up?

 

So i put in a 60a 14v automotive relay. The relay doesn't run as hot now but it's still warm. The other relay was an old one i had in the garage for quite a while so it wasn't the best thing to run in there anyways.

I went ahead and hooked back up both pumps and drove the crap out of it. The pressure was set again at 42psi at idle and after checking it with back to back runs or just cruising over the course of the day it occasionally was down to 38psi but that was as far as it dropped. My a/f seems to be ok in boost and it's actually quite rich on tip in.

 

I've gone through every wire and nothing looks bad. All my connections are soldered. I even soldered the wires into the pins for all the connectors just so none of them pull out and to get the best connection.

I have a 4 gauge wire from the battery running to a fused distribution block then about 8" of 14g wire from that to the relay then on to the fuel pump itself. These were all installed last year and look in great condition.

I ran both pumps separately and each produced the same 42psi sometimes and it would drop to the lowest of 38psi. Both pumps were the same outcome after testing it driving around.


Rich, i also forgot to comment on your fuel pressure question. I do not have a way of knowing what the fuel pressure is doing while i'm driving. I assume it's ok once i boost because my a/f is ok under boost. I'm just concerned that i'm seeing different fuel pressures at idle when it should be exactly the same every time (or so i'm told).

 

1st question for boost is what is the wastegate spring pressure, i had greddy tt and when it got hot with the 8psi spring it would only hold 14psi with blitz boost controller, but when it cooled down it would hold 18psi. swapped out to 14psi spring and dont have any issues now.
I also had a similar problem with fuel but i had a typhoon fuel pump, it turned out to be a bad FPR, changed it out and no problems now. My buddies got a g with the same problem as you, he fixed it by putting 2 FPR on the car. 1 per line. he had done a 10gallon pump with both running through fpr, but separated and saw which pump did what, and when he separated it he had no more problems, you said you had 2 FPR only 1 installed, its worth a shot.