GC99TA

iTrader: (30)

EDIT: Problem Solved. See Post #22

I've been chasing a lean condition at WOT and have a few questions. I currently have no way of monitoring my fuel pressure, but I have noticed that both my in-dash voltmeter and autotap logged ignition voltage dive to 11.XX volts at WOT. However a digital Volt gauge plugged into the cig lighter doesn't budge from 13.XX Volts during the entire run.

I suspected belt slippage at the alt, so I installed a Katech tensioner, which didn't change the condition at all. Anyway my real question is, if the voltage at my alternator is dropping at high RPM, would that affect my fuel pressure enough to cause a WOT lean condition, or would the battery be able to supply enough voltage for that short (say 10 seconds) period of time?

The car has a stock intank pump, an inline Walbro 255, and SVO 42lb injectors. Most other mods are in my signature. Thanks guys.

2THOUSANDZ

Yes, your pump isn't getting enough volts to keep up with the fuel demand.

Do you have a hot-wire kit?

How old is the alternator?

STALL UP

iTrader: (2)

I would say that the lean condition is coming from the inline 255 being feed /choked by the stock intank.

GC99TA

iTrader: (30)

No hot-wire kit. The alternator was replaced about 6000 miles ago. Bought it from Advance.

Do you think the problem is with the alternator itself, or is there just too much of a voltage demand running both pumps? I should also say that I do have underdrive pullies, but I would think that would be more of an issue at low RPM and not at high. The car charges fine at all other RPMs and conditions except heavy load and high RPM.

GC99TA

iTrader: (30)

I had someone mention that once before. I'm not saying that it's not the issue, because I'm open to any possibility. But, I've had the inline installed for several years and have put alot of nitrous (dry) to this thing and have never had a WOT lean condition before.

Now that I see two problems at once (voltage drop at WOT and lean condition at WOT), I was more likely to associate the two together. However, I still may remove the inline and try making a few passes on the stock pump alone.

Have you seen an inline pump cause a lean problem before? Thanks.

MeentSS02

iTrader: (11)

Figure out what is causing the voltage drop...that would be my primary concern. Once that comes back, your fuel pressure should too, and that'll take care of your lean condition. Voltage drop like you are having at WOT is not a good thing.

2THOUSANDZ

I think the problem is somewhere in the charging system, rather it be the alternator or battery. I don't think the underdrive pulley has anything to do with it.

How many things/accessories do you have on when the car is under heavy load? These all play a part in how much voltage the pump will be getting.

I've never dealt with a in-line pump, so i can't help you out there. I know the principle behind the pump. How does this wire up?

Also, I would not be spraying the car until this is figured out.....

GC99TA

iTrader: (30)

Yeah, I posted in the electronics forum asking specifically what could be causing the voltage drop issue. I want to get it solved whether it's causing the lean condition or not.....although I highly suspect it is after all this feedback. Since I'm not getting any feedback in there yet, any ideas in here about what could be causing this? Can a bad ground cause this? Too much load from having two pump? Bad regulator in the alt? Remember, it only does this at high RPM.

GC99TA

iTrader: (30)

I'll have to see if I can dig out the receipt for the alternator. I can't remember if it had a lifetime warrenty or not. I get this same condition with two different batteries (diehard gold and my lightweight Odyssey), so I'd think the alt over the battery.

There isn't much on at all.......headlights are off, stereo system and AC have been removed completely. The only things I can think of that are being powered (aside from the obvious like the PCM ect) is the additional fuel pump.

My inline pump is powered by a dedicated hot wire coming off of the battery. This dedicated hot goes through a relay, which is triggered by the stock pumps 12V source. Basically, when the stock pump gets power, the relay gets triggered and the inline gets power straight from the battery.

Oh, and yeah, there's no way in hell I'll be spraying this thing anytime soon I hate seeing it go that lean just on the motor. Scares the **** out of me, but oddly enough, I get very little if any KR. I would think my Wideband was giving false readings if it weren't for the stock O2s showing lean too.

Old Geezer

iTrader: (3)

Bad grounds.
Corroded bat ends.
Pump feed wiring fubar.
Pump grnd[s] bad.
Relays bad.
Batt cells going south.
1 of the two pumps took a crap?
GET a FP gauge, and see WTF the FP reads when this happens?

GC99TA

iTrader: (30)

Thanks. I'll start checking grounds, relays, and pump wiring. I've had this condition with two different batteries, so I've ruled that out, as well as the terminals.....they're real clean. I can hear my inline pump running, but I may need to take a closer listen for my stock intank pump.

Does anyone know where I can get a manual FP "test" gauge with a lead long enough to hook to the schrader valve and still be able to tape the gauge to my windshield? At this point I really don't want to buy a more permanent type FP gauge (although it probably wouldn't hurt).

RAMPANT

iTrader: (17)

I ordered one of these to make sure I do not have this issue.

http://www.speedinc.com/cont.cfm?cid=C0000096


I had heard of it before and liked the concept.

GC99TA

iTrader: (30)

Thanks! That's pretty cool. I might have to invest in one of those myself......once I determine what's causing the root of my problem.

MeentSS02

iTrader: (11)

I would look towards the alternator as a possible problem source...seems that if anyone has problems with them, they have been from the ones they got from Advance/Auto Zone with the lifetime warranties. They don't tend to be the best quality...if you are seeing the drop in voltage on your in dash volt-o-meter, I'd look no further than the alternator.

GC99TA

iTrader: (30)

Yeah, the alternator is getting replaced before I spend any money (or too much time) on any other solution. Unfortunately, I have to wait about a week or so before I can exchange my alternator though. The receipt (warrenty) is in the box, which is in my storage shed behind my in-laws' house in PA. They're mailing me the receipt tomorrow. Oh well, I have to work all weekend anyway.

I'll be sure to post up once this is all resolved. I've searched and found a few other people that have had this exact problem (at least one with a reman alternator). I PM'd two of them about the resolution; one guy hasn't had a chance to replace his alternator yet and the other guy said he thinks his was from belt slippage from not having his manual tentioner installed properly?

Fran D

iTrader: (5)

Do you have an external fuel pressure regulator or are you relying on the in-tank POS?

GC99TA

iTrader: (30)

In-tank for now.

Fran D

iTrader: (5)

Well, as already suggested in this thread, you may want to try a hot-wire kit and, perhaps, the voltage booster. Both are pretty simple fixes and they may help. However, I found that the in-tank FPR can be a real liability. I'm not making anywhere near your power (<112 MPH), but I was unable to solve a similar high RPM lean-out until I had a stable, deterministic fuel pressure. I went through a Racetronix pump and hot-wire kit (after my stock pump failed) and I also use the voltage booster (you do need to make sure you're getting 13+ V at the pump at WOT). Both helped, to a degree, but didn't solve it. Cutting in the external regulator seems to have taken care of that.

Just some food for thought.

GC99TA

iTrader: (30)

Thanks. That's very good information. I'm normally as proactive as I can be (subject to my finaces) to upgrade things BEFORE they become a liability, however I haven't done a real good of a job on my fuel system. The inline Walbro was kind of a bandaid fix I used years ago before the Racetronics kit came availabe, and until now everything had peformed very well. I'm already compiling a list of fuel system upgrades, to include a Racetronics in-tank set up with the hotwire kit, and a return-style regulator close to, if not on the rails. What I hadn't considered was the voltage booster until RAMPANT and you brought it to my attention. I'll be adding that as well. Hopefully I'll be replacing my alternator later this week see if that at least cures the voltage drop issue, but i won't be fully satisfied (or spraying the car) until I'm sure I have solid fuel pressure 100% of the time.

Where did you plumb your regulator? Is it physically on the rails, or just mounted on the DS inner-fender? Still stock rails I assume? Thanks.

Fran D

iTrader: (5)

Yep, stock rails, I don't need anything more at the moment. I used the external regulator to replace the stock fuel distribution tee in front of the left rear tire (it's where my return line goes back to the tank). Set it once to 59 psi and have now forgotten it.