Speed Density question

~The Jester~ · 06-16-2004, 06:56 AM

A friend of mine recently bought an 88 GT. Car ran really well, but lately he's complaining that the car is running really lean and won't get out of it's own way. Any ideas??? He was thinking O2 sensor, but I thought they usually made the car rich when they went bad.

Help??? P.S. He's a recently converted Chevrolet guy, so I don't want him to get a bad taste in his mouth for Fords already.

Dark_5.0 · 06-16-2004, 02:08 PM

Sounds like a weak fuel pump to me or a clogged fuel filter. I would change them both and see what happens.

tmoss · 06-17-2004, 07:37 AM

At wide open throttle, the EEC ignores the O2 sensors, so if your talking about lackluster WOT performance, I agree about fuel delivery. Don't forget the MAP sensor either, but if it is not getting enough vacuum signal and it's good it makes the motor rich, not lean. Could be going bad though.

skiwesser · 06-17-2004, 04:23 PM

If the fuel pump sounds good when it cycles when you turn the key on, then I'd change filter first, I guess thats a given.
When my pump went out it just would'nt start one day, and I could'nt hear it cycle(no whining sound like usual), so I checked that it was getting power and knew it was gone. If you can hear it cycle when you turn the key on I'd get a fuel press. guage that hooks to shrader valve first( you can tell if your getting fuel by pressing shrader valve, but be careful it'll spray) before assuming it's the pump and swapping it out. BTW if it is the pump upgrade!!

~The Jester~ · 06-18-2004, 06:34 AM

Thanks for the help! I'll get bowtie boy headed in the right direction. I thought it was a fuel problem, but I couldn't find the float bowls or a Holley black fuel pump ANYWHERE on that car. HA!

Thanks again!

06-16-2004, 06:56 AM	#1
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Speed Density question A friend of mine recently bought an 88 GT. Car ran really well, but lately he's complaining that the car is running really lean and won't get out of it's own way. Any ideas??? He was thinking O2 sensor, but I thought they usually made the car rich when they went bad. Help??? P.S. He's a recently converted Chevrolet guy, so I don't want him to get a bad taste in his mouth for Fords already. __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

06-16-2004, 02:08 PM	#2
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Sounds like a weak fuel pump to me or a clogged fuel filter. I would change them both and see what happens. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

06-17-2004, 07:37 AM	#3
tmoss Registered Member Join Date: Mar 2003 Location: Saint Louis, MO Posts: 634	At wide open throttle, the EEC ignores the O2 sensors, so if your talking about lackluster WOT performance, I agree about fuel delivery. Don't forget the MAP sensor either, but if it is not getting enough vacuum signal and it's good it makes the motor rich, not lean. Could be going bad though. __________________ Tom (Torque) Moss 88Gt 5spd Vert, FLowmaster Catbacks, stock cam advanced 4° @ 108.5° ICL, NMRA prepped GT40P heads 1.85/1.55 valves and 1.7 rockers, MAC P headers Jet-Hot coated, 97 Exlporer intake (ported lower), TB and injectors. 277RWHP/330RWTQ (SAE). http://www.fastlanecars.com/

06-17-2004, 04:23 PM	#4
skiwesser Registered Member Join Date: Sep 2000 Location: rock hill,S.C. 29730 Posts: 420	If the fuel pump sounds good when it cycles when you turn the key on, then I'd change filter first, I guess thats a given. When my pump went out it just would'nt start one day, and I could'nt hear it cycle(no whining sound like usual), so I checked that it was getting power and knew it was gone. If you can hear it cycle when you turn the key on I'd get a fuel press. guage that hooks to shrader valve first( you can tell if your getting fuel by pressing shrader valve, but be careful it'll spray) before assuming it's the pump and swapping it out. BTW if it is the pump upgrade!! __________________ 88 GT: subs,pullies, 1 3/4 longtubes, flowmasters, AFR 165's,T,F #1 cam,Thyphoon intake, 24# inj., 73mm C&L,65mmT.B., 190LPH pump, Eagle sir rods, forged pistons in a newly rebuilt 306. DYNO TUNED TO 300.97 RWHP 337RWTQ

06-18-2004, 06:34 AM	#5
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Thanks for the help! I'll get bowtie boy headed in the right direction. I thought it was a fuel problem, but I couldn't find the float bowls or a Holley black fuel pump ANYWHERE on that car. HA! Thanks again! __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

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