Hows it going, Im 21 years old, and so is my TBI 305 RS . I've been in the dark on trying to fix a problem, and if you take the time to read this i would greatly appreciate it. My car has been running like a POS losing all compression when its warm and I try to accelerate or go uphill. It will backfire, hesitate, and then just lose all power causing me to let off the gas until it regains stability of fuel/spark. I say fuel or spark because i don't know which one it is. I have put in new spark plugs/wires (in correct firing order), distributor cap/rotor, fuel filter, and other things. I HAVE NOT REPLACED the O2 sensor, the EGR valve, either of the 2 fuel injectors, fuel pressure regulator, or fuel pump since Ive had the car which has been almost 6 years now (current mileage is 121 K). I bought the haynes manual for a complete engine tear down/rebuild for my car and in it lists all diagnostic symptoms, causes, and etc. In that it has the ignition timing listed as a cause for all the symptoms im having but it also lists the fuel elements. I haven't had the timing adjusted so I was hoping that is my issue. My uncle and a couple other people think it could be the throttle body, the fuel regulator, or the fuel pump. The service engine light DOES NOT come on and I don't know if the injectors or regulator would make it come on if faulty. Also, "it" is worse when it is hot. When it is a cool 50 degrees outside it wouldn't act up, only rarely, but the heat is making it worse it seems like. If you are still reading this my main question is do you think the timing is the problem, the fuel components, or something as simple as an o2 sensor? I don't know if the O2 Sensor would pull a code, and I am NOT getting the service light on at all, which does work. Timing? Fuel Injectors? Fuel pressure regulator? Fuel pump going out? or the throttle body itself? Which do you think? I really would like to hear from another 3rd gen owner. Thank you and please give me some insight if this sounds familiar.

 

Could be timing. Cost nothing to check it, so I'd start there. If you don't own a timing gun yet, now is a good time to buy one. You'll be glad to have one.

Welcome to the forum.

 

I'd start with a simple check of fuel pressure.

You can either buy this adapter:
OTC 7665
Actron CP7817

OR

go to Autozone and loan-a-tool their master fuel injection test kit,
Part Number: 27167
Alternate Part Number: CP9920A
which also contains the TBI adapter. It's $150 to rent, but you get your money back when you return it.

I bet you'll find the fuel pressure to be under 9 psi.

 

if my timing is good, and then i check the fuel pressure, if the fuel pressure is good then it would be safe to say i need to replace the FPR? and if the fuel pressure is low i should replace the fuel pump? does that sound right?

 

what should my fuel pressure be for the 305 5.0 V8 TBI???????

 

I agree that you need to start by checking your fuel pressure. Factory spec for TBI is 9-13 PSI.

Also, just because you don't have a check engine light on doesn't necessarily mean there are no stored codes. To check, just stick a paper clip in the two terminals on the rightmost side of the top row of your ALDL connector (it's a 12 pin connector under your steering column, google image it if you have trouble finding it), then turn the key to run but don't try to start the engine and count the blinks of the check engine light. The blinks should come in pairs, so the standard 1 blink, short pause, 2 blinks represents 12 and is normal. Anything after that (23, 45, 54, etc.) you should write down and post back here.

 

9-13 psi is the spec. You'll want to be toward the high end of that.

If your pressure measures good, your FPR is good.

What you're describing is a loss of a power under high-load conditions, which is pretty typical of a fuel pump failing or the rubber fuel hose coupler in the tank failing. The fuel supply can (barely) keep up at low loads, but then when hi fuel flow is demanded your fuel system can't keep up.

You can get proof-positive of this if you can get the gauge within view while driving the car... stuck under a wiper blade or similar, and go engage in the driving activity that makes the car loose power.

 

thanks guys, I changed the fuel pressure regulator, took it for a drive and i didn't have much hesitation at all getting on the highway accelerating. The real test will be when it is nice and hot outside. Ive had the car for 6 years, put 65 K on it, so should i replace the EGR valve if i havent? and would the EGR valve put my service light on if faulty?? Also, I will try the paper clip trick and see if I am pulling a code, honestly i never knew my car would pull a code and not have the light come on so this i am new to. If my problem is still there should i replace the fuel pump, or the egr valve ? I didn't get to test my fuel pressure, this older guy i knew said to change the regulator and then the egr valve if nothing, but again, would the egr valve throw a code? and would it be the service light or blinks?

 

i will check it and get back to you, and thanks in advance

 

"much hesitation" MUCH?! There shouldn't be any. Try running some injector cleaner through your tank, have you checked for gas leaks?

 

If you don't pull the codes first and check your actual fuel pressure under load, you're just going to be throwing parts (and money) at the car blindly. If you have deep pockets and lots of time to spare, that might work out for you, but if you're on a limited budget like most people, it's much smarter to take a diagnostic route and find out what is causing your misfire condition so you can get to the root of the problem.

 

I agree. If you replaced the FPR without so much as taking the time to check your fuel pressure, you clearly aren't interested in solving the problem, just buying parts.