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ive taken my car to a mechanic today and he doesnt know the problem. ive had this power loss since i rebuilt my engine back in may.
about 180-190psi compression
33psi fuel pressure
about a year old 02 sensor and temp sensor, new distributor, plug, wires, rotor, cap, tps sensor, maf sensor, new fuel filter, new clutch, new fuel injectors. everything seems to check out fine. got a backpressure test on my car today and they said its basically perfect. not sure what else to look for. ignition timing is right at 10 degrees. it just lags, especially on the highway. the car had pull before i rebuilt my engine and now after about 5 months of going back and forth with it and still nothing.

i mean something has got to be wrong.

i did some more tests today, replaced the fuel filter again cuz my old one broke. did a fuel pressure test. got about 35psi at idle but if you rev or accelerate the car the pressure drops instantly only about 5lbs. and if you pinch the line the pressure increases very instantly. which on the manual shows the pressure regulator being bad. i dont think the pump is bad, but the regulator i have it costs 231 bucks and i only see it for sale at rockauto. i wonder if i can use the 1 vacuum port regulator and plug off one of the solenoids to the FPR. anyone tried this? i had a aftermarket regulator on there but it never really worked and i think it was just a piece of crap and had pressure all over the place from 20psi all the way to 60psi one time i checked it. so i just tossed it and went back to my old one.

i think i may have found my problem, i was going over my vacuum hoses and i took off the hose that goes to the vacuum chamber and bam just filled with gas. wtf? what would cause this? i mean the whole thing was heavy and a ton came out. totally weird huh?

id say your FPR is bad, try getting one from a junkyard. shouldent cost more then 20 bucks.

Bumpysbro wrote:i wonder if i can use the 1 vacuum port regulator and plug off one of the solenoids to the FPR. anyone tried this?

Hopefully others will chime in here if they've tried the FPR mod in this manner to maintain constant increased fuel pressure. First, would recommend you follow the FPR testing steps #1-8 on pages F1-120-121 of the online shop manual if not already done so. If the FPR is bad, wouldn't seem to make any dif if you did the PRC/FPR mod or not. Also, ya mentioned having no prob til the engine rebuild was completed. Are you confident the PRC solenoids are good and the related vac hoses are all definitely intact? Maybe something got punctured during the rebuild? (EDIT: Oops, just saw your followup post about gas in the vac line. I was writing when that came across...)

The recommended method for a PRC solenoid/FPR mod is to tap a switch into the PRC solenoid control line and ground it whenever you want/need the extra fuel at lower/mid rpms. This is sometimes done to reportedly produce a couple more hp at lower/mid rpms when fuel pressure would otherwise range anywhere from 28-44psi. Since fuel pressure rises to 44-55psi range at WOT when intake vacuum is lowest, you can also achieve this higher pressure level as a constant by simulating this low vac condition in the way you have suggested. Fuel mileage could suffer though. In this condition the ECU runs the engine in "open loop" and ignores the 02 sensor. To make it happen the way you asked about, on the FPR, I believe you would d/c the upper vac hose and plug the upper FPR port and the hose = zero intake vacuum condition. The lower hose would remain attached to the lower FPR port.

Sorry I can't offer actual experience with the modification method you asked about but thought I'd give your interesting problem-thread a bump cuz it's got me curious too... and I didn't see it getting much traction with other members responding yet...

ya i think that too, maybe the diaphram ruptured but sure is weird that i got gas in the vacuum chamber. i mean alot too, never noticed it until tonight. and i thought i was getting a egr valve code but turned out to be a Purge Solenoid valve code, since that is interconnected with EVAP system to the charcoal canister. im gonna test my other prc solenoids tonight and see where im at. thanks for the response guys i really appreciate it, just a tought problem that i think i might be coming up on.

i really need to get a vacuum gauge and see what my readings are probably would tell me alot. i mean with the gas in the lines must of choked the whole sytem for air. during the rebuild i got new vacuum hoses you know the color ones maybe their crap and choking off the whole system. maybe something there huh. thanks guys


oh and do you guys have any idea where to buy new solenoids you know like Purge, PRC, or VICS solenoids for the engine. or are they just dealership parts only

i got a vacuum pump and i did a test for vacuum on the intake manifold. i got a reading of 19 or 20inHG. so i guess that more then perfect correct? so i guess my problem is fuel related. i put in a different fuel pump and the car seems to have more power. i still think the pressure regulator is dead but just my guess. ill see if i can find one in a junkyard but if all else fails ill just buy a new one. thanks guys

i think i nailed it down, i tested fuel pressure and when i disconncted either 1 or both of the vacuum hoses to the regulator the psi reading stayed the same. it says on the online manual it should jump either 10 or 20psi correct. i guess thats my problem, i checked the egr but tests showed up that its ok and working. thanks guys ill keep you updated
Jon

I dont really have anything to add about the FPR other than I have a spare I might consider selling to you if the price is right. PM me with an offer you think is fair. I was going to save it.. but I am going to sell my RS as soon as I have the GS on the road.. so I dont really have a need for it. Also.. 18-20 HG is right about what you would expect for decent vacuum.. the real indicator though is how steady the needle stayed. If it was rock solid.. your in great shape.. bouncing around a bit.. no big deal.. bouncing so fast you cant really see the needle.. valve seating problem.. which you shouldnt have since you just rebuilt the engine.

There is another thread around here where I posted a TON of information on how to use a Vacuum gauge as a diagnostic tool. I think the thread was by Bling Bling and he was asking about various aftermarket gauges to install in his car. Hope this helps.

Tunes67

Hopefully you get everything settled eventually. It'll be nice to have someone possibly available for a norcal meet.

ya same here. once i get this done i wouldnt mind a drive to meet up somewhere

wow cant believe i overlooked this, when i ordered new plug wires when i was installing them i broke the 4th one so i decided to reuse my old wires. and i tested it bam all other wires were getting like 8.5ohms or something like that and that one was getting like 2 or 2.5. i tried a another wire wow what power. i know my regulator is bad but damn that got alot of it back. haha always check the easy ones first.

if you had fuel in your vac lines i wouldent be driving the car much without replacing the regulator, if fuel gets into your break booster who knows what it will do.

ahh ya i didnt think of that, i did notice that my brakes are noticeably weaker and harder to stop. i think the gas got trapped in the vacuum chamber. i hope i did find any through the other lines.

well i put a new fuel pressure regulator on and tested the fuel pressure bam came up perfect but i did a pressure hold test and the manual says it should stay above 21psi for more then 5 minutes. mine stayed above 20psi for 5 seconds and went to 0 in about 20 seconds so thats bad. and i disconnected my egr and conditions improved. i get my new pump tomorrow and see what happens. thanks to tunes who supplied me with my new regulator.
Jon