I am just curious what anyone knows on what will happen if the fuel pressure is set too high. I had mine set at 65psi for quite a while due to not measuring it with the vacuum off, stupid me, how was I to know the damn install directions didn't mention anything. Could this harm anything? And how would this effect performance? Thanks.

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87 GTA 350 L98
K&N filters, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed IAC,

Fastest ET's
Stock-0-60 6.8, 1/4 15.0 @ 94
Best-0-60 4.7, 1/4 12.8 @ 112
Norm-0-60 5.2, 1/4 13.2 @ 108

 

Yea I know a negitive effect

BAD GAS MILLAGE :P

hehe, but seriously, better rich than lean.

 

Bad gas mileage is probably right, but shouldn't be anything real bad, hell a lot of supercharger kits add fuel by bumping the pressure under boost, unless your engine through some codes for being to rich i wouldn't worry bout it, but if it was to rich you could fry your cat, accelerate wear on your cylinder walls, and clog up your 02 sensor. But you're probably ok.
John

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89 Formula 350
86 Cutlass Salon
93 GMC 1500
97 Yamaha V-Max

 

OK beter lean than rich for performance. There are a lot of problems that come with too high fuel pressure. YOu are running you engine way rich. That will foul plugs and crud up you emissions equipment, especially you catalytic converter. This will also cause excessive carbon build up on valves an piston tops. This will also burn up you O2 sensor faster because of all the crud that will build up on it.
Yes you will also get bad gas milage. This is because you will be throwing in o much more fuel that will just goto waste. All the extra fuel has to come from somewhere and that means your fuel pumo will have to work a lot harder and will burn it up to.
Dont set it abouve 48psi with a stock pump and dont set it above 44psi unless you need a lot more fuel for a large increase in air flow.

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A fuel pump will generate just so much work, as you crank up the pressure, the volume it can deliver drops. Reset it and clear the computer and see how you do.

The ecm will try to maintain a 14.7 if it can't then you get a SES light.

Sounds like you had it soo high that instead of rich you were about the same as far as what the ecm was seeing or you'd set a code 44 or 45

 

Thanks for all the input guys, hopefully there will be even more. I had orginally intended to have the pressure set at 50 from a lot of recommendations, but didn't know to clog that vacuum line, and it appears that at idle it was actually putting 65. I did in fact blow a cat, although I think it took a while. However, I recently replaced it before I lowered the pressure and appears to have blown another cat. Can anyone think of any problems that would blow a cat this quick it was only like two weeks or less than 20 miles and not running that hard too. The bad cat is still on the car, although I will be gutting it out soon. I haven't really been using it in the mean time. I have the fuel pressure now set at warm idle to about 49.5 psi, and the timing will be set about 9 degrees. I also plan on capping the AIR stuff and removing just the belt from the smog pump. That way I can put it back on and swap a good cat when it is time for emissions. But I fear that there might still be a problem somewhere that made all this happen in the first place, but don't know what it is. The guys at random tech said that the cause for the extreme rich condition could be a missing cylinder, leaking injector, or A/F ratio way off the mark. How could I check for the leaking injector? I think I would probably feel the missing cyl. and I think the computer would put up a code for the way off A/F especially since I just put in a brand new O2. I'd really appreciate any further help.

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87 GTA 350 L98
K&N filters, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed IAC,

Fastest ET's
Stock-0-60 6.8, 1/4 15.0 @ 94
Best-0-60 4.7, 1/4 12.8 @ 112
Norm-0-60 5.2, 1/4 13.2 @ 108

 

some fuel injectors will lock up under high
fuel pressure.

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http://darcom.home.texas.net/

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