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05-02-2008, 09:24 AM
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#1
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Regular Member
Join Date: Jul 2007
Location: St Peters MO
Posts: 31
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Symptoms of a bad fuel pump?
- i have a 1994 A4 z28 and i took my car to the dyno about a week ago and they couldnt get it over 4500RPM on it and it only dynoed at 217 rwhp (the car ran mid 13's back in november and nothing has changed) which didnt make sense....seemed to be cutting out real bad and i just replaced my opti and plugs about 5000 miles ago..the car seems to bog down real bad too when i first start it up and sounds like its poping and missing untill it shifts
ive made sure the cats arnt clogged, ive replaced the fuel filter and ive ran my OBD1 scanner and i keep getting a "Fuel lean malfunction" reading
heres a vid of how the car runs when its first started up
http://s34.photobucket.com/albums/d1...t=100_2220.flv
could it be my pump? i hooked up a pressure tester and im getting around 20psi and less when i drive the car
help!
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05-02-2008, 10:29 AM
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#2
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Regular Member
Join Date: Jun 2006
Location: Winnipeg Manitoba,
Posts: 318
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20 PSI is awfully low, should be more then double that.
check your fuel pressure regulator, if its ok, then it sure seems like your fuel pump crapped the bed.
__________________
1994 Trans Am GT M6, MSD 8.5 mm wires, MSD Blaster coil, !cat, TB bypass, Flowmaster american thunder exhaust, Custom Stainless 3.5" Quad exhaust tips, Custom CAI, 561 heads w/ stage 3 port & polish, 3 angle valve job, comp 918 springs, LT4 Hot Cam, Comp Cams 1.6 R/R, port matched intake, 4:10 gears, Eagle Alloys.
Sounds like a raped ape! 
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05-02-2008, 11:41 AM
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#3
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Regular Member
Join Date: Apr 2008
Posts: 192
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Quote:
Originally Posted by JesusKnievel
- the car seems to bog down real bad too when i first start it up and sounds like its poping and missing untill it shifts
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My old firebird did exactly the same thing! It would also feel like a misfire when the car when into overdrive. I changed the fuel pump and it fixed all my problems, like he said also check the regulator and the filter. Also if you get a pump from autozone or anyplace, TEST it before you put it in! if you do it right and drop the tank you will be VERY pissed when you strap the tank back in a try to fire her up and you get no fuel. I had to tank my back and get a 2nd...I hate autozone....
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1993 L32 v6 192,000 - GONE!
1996 LT1 v8 60,000 SLP ram air, !air, !egr, !evap, cc503, 1.6rr, pacesetter LT w/ORY, flow master 80, PerformaBuilt lvl 2, 3200 stall, 32# Red tops, Tune by Soloman
1997 LA1 v6 Venture Van!
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05-02-2008, 01:18 PM
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#4
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Regular Member
Join Date: Jul 2007
Location: St Peters MO
Posts: 31
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well im doing the old "hack the SH*T out of the trunk" square cut thing
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05-02-2008, 02:39 PM
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#5
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Regular Member
Join Date: Oct 2007
Location: Orange County, CA
Posts: 592
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When my pump went bad, the symptom was a high-end stumble around 5000rpm. I hooked up a gauge and got 40ish at prime and idle but the pressure would drop to ~20 close to readline. Replaced the pump, and pressure was good to go again. I also did the trap door method.
__________________
"When you are knowledgeable about all aspects of your rebuilding project, it will likely succeed with flying colors."
"If you don't know that it's right, presume it isn't."
1999 Chevrolet Camaro SS, M6, K&N FIPK CAI, Mangaflow Cat-back
1997 Chevrolet Camaro SS, M6, Flowmaster Cat-back
Project: LQ4 build-up in progress
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05-03-2008, 06:49 PM
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#6
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Regular Member
Join Date: Nov 2007
Location: AZ
Posts: 188
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20psi ouch. That sounds like the pump, my car did the same thing it could only build about 24psi. I got a racetronix kit, and installed it using the trap door, solved the pressure issue. The trap door is the way to go, only a couple minutes of cutting. Good luck, hope it fixes your pressure!
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05-05-2008, 04:01 AM
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#7
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Regular Member
Join Date: Aug 2006
Location: Benton Harbor, MI
Posts: 895
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had this issue with both my roadmasters. the first one, I drove home 300 miles like that... it was a pain on the highway! It had a mean miss, and back fire. I swapped a bunch of parts before I put a fuel PSI gauge on it, and saw 20psi.  car was much quicker after that.
2nd car, it ran really really slow at the dragstrip, stumbled off idle, and had good pressure(43) at idle. it just felt slow to me. replaced the fuel filter, and it gained 60hp. then a week later it died at the gas station, right after I put a full tank in. I got to a parking spot, and then it wouldn't start...
the trap door method scares me. I don't need a another exposed area to allow rust. Maybe dropping the tank of a B-body is that much easier?
__________________
~Cory Magner "My name is Cory, and I'm an addict."
95 DCM Buick RMS 14.21 at 91.79 "Jesus" Motor Swap at 85k
95 DCM Buick RMS 13.52 at 99.33 Buffmans Car Cracked Piston at 180k 
RAISS, Tri-Y's, Pypes X pipe, Spintech Prostreets, 3000 Edge, 3.73's, Eaton Posi, and the rest of the Bolt-ons.
Coming soon! 845 cammed 96 9C1 engine.
And 7 other LT1 B-body's... Is there Rehab for this Sh*t?
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05-07-2008, 06:27 PM
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#8
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Regular Member
Join Date: Jul 2007
Location: St Peters MO
Posts: 31
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whats the probability of it being the fuel pump over the regulator? im buying a used one tonight out of a 95 z28 with 30K miles on it for 20$
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05-07-2008, 06:39 PM
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#9
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Regular Member
Join Date: May 2008
Location: Ft. Worthless, TX
Posts: 178
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regulators dont go bad very often, fuel pumps seem to be common on these cars. Mine has 91k and i just replaced the fuel pump.
trap door method style and was done in under 2 hours taking my sweet time.
__________________
95 Trans Am A4, leather, T-Tops, flowmaster, & !Cats
[SIGPIC][/SIGPIC]
84 FJ60 Toyota Land Cruiser, Lifted, Locked, and Wheeled. ROTW
93 Toyota Camry LE
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05-07-2008, 06:40 PM
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#10
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Regular Member
Join Date: Jun 2006
Location: Winnipeg Manitoba,
Posts: 318
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Quote:
Originally Posted by JesusKnievel
whats the probability of it being the fuel pump over the regulator? im buying a used one tonight out of a 95 z28 with 30K miles on it for 20$
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More then likely the fuel pump at that low of a pressure. Although you can sometimes save money with used, I dont think this is one of those places you want to cheap out. Lot of work if the pump only lasts a little while again. Its like buying used underwear, you just dont 
__________________
1994 Trans Am GT M6, MSD 8.5 mm wires, MSD Blaster coil, !cat, TB bypass, Flowmaster american thunder exhaust, Custom Stainless 3.5" Quad exhaust tips, Custom CAI, 561 heads w/ stage 3 port & polish, 3 angle valve job, comp 918 springs, LT4 Hot Cam, Comp Cams 1.6 R/R, port matched intake, 4:10 gears, Eagle Alloys.
Sounds like a raped ape!
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05-07-2008, 08:39 PM
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#11
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Regular Member
Join Date: Jul 2007
Location: St Peters MO
Posts: 31
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well i checked again and my pressure was 19 at idle and 11 at around 5K..
hoping to swap the pump out tomorrow so i can run this b**ch Friday night
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05-07-2008, 10:37 PM
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#12
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Regular Member
Join Date: May 2008
Location: Ft. Worthless, TX
Posts: 178
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Quote:
Originally Posted by DJ_Kovacs
More then likely the fuel pump at that low of a pressure. Although you can sometimes save money with used, I dont think this is one of those places you want to cheap out. Lot of work if the pump only lasts a little while again. Its like buying used underwear, you just dont |
u dont use hand me down undies? 
__________________
95 Trans Am A4, leather, T-Tops, flowmaster, & !Cats
[SIGPIC][/SIGPIC]
84 FJ60 Toyota Land Cruiser, Lifted, Locked, and Wheeled. ROTW
93 Toyota Camry LE
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05-08-2008, 09:28 AM
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#13
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Regular Member
Join Date: Jun 2006
Location: Winnipeg Manitoba,
Posts: 318
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Quote:
Originally Posted by LOW-LIFE
u dont use hand me down undies? |
Hand me downs and buying used undies are two different things
__________________
1994 Trans Am GT M6, MSD 8.5 mm wires, MSD Blaster coil, !cat, TB bypass, Flowmaster american thunder exhaust, Custom Stainless 3.5" Quad exhaust tips, Custom CAI, 561 heads w/ stage 3 port & polish, 3 angle valve job, comp 918 springs, LT4 Hot Cam, Comp Cams 1.6 R/R, port matched intake, 4:10 gears, Eagle Alloys.
Sounds like a raped ape!
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