My 87 IROC, 305TPI, 5sp has been running rough at light throttle openings. When the pedal is mashed there is no problem. The symptom is that the car is cutting in a out (quickly) and therefore bucking. I checked the plug wires and put in new Splitfire plugs. The old plugs had 40K on them and were very white at the eletrode. I assume this means the car is running hot and the timing is suspect?? Is there anything else it could be (not I have added fuel injector cleaner the last couple of weeks). Thanks.

Tom

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'87 IROC, 305TPI, 5Sp, , 190K miles, all original except for K&N filter, Vin F

 

I bought my firebird (5 speed too)cheap from a lady because it was doing that. Fuel pump is about toast.



------------------[*]my Formula Homepage [*]Collision P/Ns & Diagrams

"Always do sober what you said you'd do drunk. That will teach
you to keep your mouth shut."

 

fuel pressure and volume are definitely a suspect but I wouldn't just stick a pump in it. thinking you're fixing it. You might as well do a good tune up like fuel filter, air filter and such.

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Kyle Osterholt
Okarche, Oklahoma
ASE Master Certified
86 T/A 383 TPI
89 TTA #1002 T-top/Leather
89 TTA #1358 Hardtop/Leather
80 T/A Pace Car
73 Opel GT
73 bronco
2000 Ducati 996 Monoposto
83 MSE #52

 

Agreed; throw a fuel pump pressure gauge on it before you drop the tank. It would suck to replace the pump and have the same problem!


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-Tom P (Hot rodded 1986 Firebird 2.8l)

 

Thanks for the input. But, if the fuel pump was about to go wouldn't the car stumble at full throttle and not at partial?? I did check the timing and when the computer is plugged in, it is way advanced. In fact the timing light is skipping around and not not constant. Does that indicate a computer problem? If I had to guess on how far the timing is advanced at idle I would say by looking that it is 20 degrees. The car does ping some as well (always has) but until recently ran smooth at light pedal effort. Could it be my MAF or IAC? I did check the computer for trouble codes and none are stored.

 

maybe the TPS is a little off or screwy?

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16

 

Yes, did replace the TPS about a year ago (in vain as it was actually my plug wires were worn out). I have the original and should give it a try and or measure the voltage across the existing one. Would that be enough though to make it run rough. I tried disconnecting the computer and driving the car (took off single wire so time the car) and it exhibited the same problem. Was ok at high throttle but no good at partial.

 

Timing bouncing around a little is normal. but when you unplug the black/tan wire it should be steady.

 

cool...another TPI 305 IROC 5spd from 87? It is black on black.

 

I should clarify...........the timing was not bouncing around with the EST connected. The timing light was eradically lighting. The mark on the timing indicator was steady. When I disconnected the wire, the light was steady and the mark was at 2Degees BTC. This is were it has been for the last year and been running good.
The car, seems to have the same hesitation problem with or without the EST wire connected. At full throttle the car runs fine, it is only at the minimal throttle opening that I am having a stumble. Again, I am getting no trouble codes.........am thinking of submiting to dealer check, although that goes against my principles.

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'87 IROC, 305TPI, 5Sp, , 190K miles, all original except for K&N filter, Vin F

 

Hmm, I didn't mean to say your pump is toast (guess I should've checked what I said sooner). What I meant to say was "fuel pump was about toast.", as in mine, my bad.

I would recommend checking your FP under load. I can't explain why mine ran fine under WOT but could nearly give one whiplash under light/mild throttle, it would jerk & cut out at cruise speed as well.

After fiddling with everything i could think of (not realling knowing much about TPI at the time) and changing countless things, I broke down to have it looked at. After missing my car for a day the shop called up & said they found the problem & had me come in to see. With a FP gauge hooked up and the car idling it was running the stock FP (37-ish psi), a snap of the throttle to rev it it would sharply drop to around 23psi then shoot up to about 40psi. They said when they watched it taking it for a spin it would do this as well & was in sync w/the jerking/cutting out.

While your problem may be something entirely different, checking the FP at least wouldn't hurt.

[This message has been edited by deadbird (edited December 03, 2001).]

 

Thank you kindly for your time. I really hope it isnt the fuel pump as in 2/00 I broke down heading to Vermont and it was the fuel pump. It cost over 500 bucks to replace it (had no choice, too far to tow). So, I guess my best option is to go to the dealer. Thanks again.

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'87 IROC, 305TPI, 5Sp, , 190K miles, all original except for K&N filter, Vin F