Car won’t start unless I press the gas
 

Everytime the car is cold, 100% of the time I have to use the gas to get it going. I usually rev it to 2k and keep it there for a sec after it cranks and then let it drop down slowly to idle. If i let go of the gas too quick, it shuts off. Also, if i rev it while its still cold, it shuts off. Now whenever the engine is hot, sometimes it will fire up without the gas. Also, when the engine is hot, I can rev it to whatever RPM I want and it will stay alive. This has been a problem for 2 years. I just need someone to narrow down the potential causes so I don’t blow my high school budget away lol. Also worth noting, the car sometimes shuts off when im turning (at least it usually happens when im turning). There has been twice where it shuts off at a stop light. IDK if that has anything to with it. The car runs perfectly fine other than all that. It accelerates perfect and runs the highway perfect

What do I need to change/ inspect? I’ve heard PCV Valve, Fuel Filter, Fuel Pump, IAC Valve, EGR Valve, and MAF Sensor.

More info: 1989 Camaro 305 TBI All Stock, 90k miles

Sorry. Ik this is alot. I’m trying to give as much info as I can to give yall an idea of what it potentially could be.

- Thanks, Kyler

Re: Car won’t start unless I press the gas
 

start with fuel pressure, you will need to get an adapter because there is no provision to check from factory. IIRC, you need 9-13 psi. I like to see 13-14 psi, no less. the stock regulator can be made adjustable. if you flick the throttle and see the needle move, replace the pump. I recommend a TPI pump from the same generation third gen. checking fuel pump voltage @ the tank with vehicle running is a good idea, should be same as battery voltage give or take a few milivolts. ability to datalog is invaluable as well with any EFI vehicle.

Re: Car won’t start unless I press the gas
 

I’ve never checked fuel pressure before. Where do I plug in the gauge at? Thanks for the reply.

Re: Car won’t start unless I press the gas
 

There are two ways of checking the fuel pressure. One adapter is for where the fuel filter is. There is another one for at the throttle body.
https://www.summitracing.com/parts/anm-01800001465
https://www.summitracing.com/parts/anm-cp7818/
a lot of parts stores rent the tester and have the adapters included.

Re: Car won’t start unless I press the gas
 

Hopefully Autozone has a rental. If my fuel pressure is too low, should I start by changing my fuel filter and test it again?

Re: Car won’t start unless I press the gas
 

Yes...but expect to need a fresh fuel pump. It's not likely the filter is the only problem when there's low fuel pressure.

Poor electrical supply to the pump (including the ground side of the circuit), clogged inlet "sock", and a plain ol' failed fuel pump are very likely root causes.

As far as the electrical supply, be sure to test both the voltage (near the pump) and the amperage draw of the pump.

Re: Car won’t start unless I press the gas
 

I would also borrow a timing light from auto zone and check timing.

Has the car done this since you owned it? Did anything change before hand? Really bad or incorrectly gapped spark plugs is also something to look at (and its free to inspect :) )

If you determine low fuel pressure do not buy a cheap pump, that is literally the one part I always insist on being OEM or a high quality race part. Its too much work to replace to cheap out on.

I don't think the fuel pressure tester autozone has on their loaner program comes with the adapter, they do sell one for around $20. The TBI doesn't have a port to test on you have to take a line loose and put the adapter in place.

Re: Car won’t start unless I press the gas
 

I’ve had the car for 2 years and this has always been a problem. I was only 15 when I got the car and someone told me that the car should do that because it’s 30 years old :confused: I changed the spark plugs a year ago with the proper gap. Since then I’ve put maybe 1000 miles on it, so I don’t think the problem is there. I haven’t touched the plug wires though.

Re: Car won’t start unless I press the gas
 

Changed the fuel filter. The fuel pump is making a growling noise now. Very loud. I made sure to put the filter in the right way. I was very careful because I don’t want to snap or twist the fuel lines. No gas is leaking. Do you think it’s about time to replace the pump?

Re: Car won’t start unless I press the gas
 

In MY driveway, no fuel pump gets replaced without testing the electrical supply (and ground) first. Voltage AND amperage of the supply, voltage on the ground near the pump.

In your case, I think it's fairly certain that the pump is damaged. I'm a little mystified that the pump didn't make noise until after the fuel filter was replaced. That's not something I can explain.

Re: Car won’t start unless I press the gas
 

Plugged or partially plugged filters will put excessive load on the pump. Resulting in eventual damage. Likely the pump was working harder and turning slower before the filter change and is now running faster and that causes noises.

These old style pumps were junk then, and are even worse junk now. Get a Deatschwerks DW200 pump kit for a C4 vette.

GD

Re: Car won’t start unless I press the gas
 

So I tested the fuel pressure. It’s around 9-10. The problem hasn’t gotten better or any worse. I still have to rev the car right when it turns over. Any other ideas?

Re: Car won’t start unless I press the gas
 

Don't need another idea. You've found an issue. 9-10 is too low. Time to find out why....low voltage to pump, plugged filter, failed hose inside tank bleeding pressure, or bad pump.

Re: Car won’t start unless I press the gas
 

I thought spec was 8--13. My '88 K1500 started just fine at 10 psi, although I eventually jacked the pressure up some trying to get rid of a false lean code created by a failed O2 sensor. (Increasing fuel pressure didn't help.)

Based on having adequate fuel pressure, I'd be looking at the data stream. Coolant temp sensor readings, IAC performance, MAP sensor output, and EGR position would be leading contenders for problems at idle when cold. Of course, its worth looking at all the other parameters as well.

For that matter, when was the last time the vehicle had proper "tune-up" services performed? Cap, rotor, plug wires, spark plugs inspected, tested, or replaced. Timing checked (including timing advance). Filters inspected or replaced. EGR operation tested. IAC passage spray-cleaned with aerosol carb cleaner. PCV operation tested. Ignition coil output tested.

Re: Car won’t start unless I press the gas
 

That's what I thought too. 9-13 at least. I'm making a list of things to check or replace on the car.

I checked the voltage going to the TPS. I got .74 at closed throttle and 4.42 at WOT. Sounds about right, but just wondering if that closed throttle reading is a little high.
So far I have:
- Cleaned IAC
- Rebuilt TBI
- Replaced starter
- Gapped spark plugs
- Replaced fuel filter
- Replaced PCV valve
- Replaced CTS
- Replaced battery (not for this problem. Just throwing it out there)

Re: Car won’t start unless I press the gas
 

OK, my mistake guys. Sorry.

I thought I had read here (repeatedly) that TBI driveability and starting issues could start at 10...that it's happy place was at the top end of a very narrow 11-13 pound range, 14 or 15 being even better if the pump and an adjustable regulator could achieve it. Good to know it can sink as low as 8 and still be OK.

Re: Car won’t start unless I press the gas
 

All good. Don’t worry about it haha.

I’m just trying to see what the problem can possibly be. It’s not gonna be pinpointed, but I just need to know where to go now. Fuel pressure is tested and it’s on the lower side of the spectrum. Now is that something to be looked at more in depth or should I continue with the search?

Re: Car won’t start unless I press the gas
 

Does the pump prime? If not, you can expect the engine to have a long crank time because the pump won't run until the engine has oil pressure.

If the pump does prime when you turn the key to "Run" or "Crank", I'd be looking at that list of tune-up items, and connect the scan tool.

Re: Car won’t start unless I press the gas
 

Pump does prime. Although when I connected the fuel pressure gauge, it looked like it was dropping a bit of pressure after the pump primed. IDK if thats normal, but is that something I should look into?

I did the paper clip trick and it flashed no codes at all. Nothing. The only code was to tell u the computer is working.

Re: Car won’t start unless I press the gas
 

I've got some thoughts that may be of help to you. I believe you may have more than one issue here.

First question, when you say the car shuts off when turning.. Is it possible that this is happening when you're making right turns when under 1/4 tank?
Second question, have you noticed the car "shutting off" while driving on bumpy roads at all?

Reason for the first question is, I've had my 88 TBI car since I was 16 and I know how the whole high school budget thing goes. If you're running low on fuel and make a right turn with some momentum all your fuel will slosh over and make the pump run dry and shut the car down.
I did it a few times in my younger years, once even with a dead battery, on my way to buy a new battery. Ahh the memories!

Then for the second question, if you notice it on left and right turns and possibly even over bumpy roads then I would certainly be looking at the wiring inside the tank for the pump and sender.
Also from experience.. at 17 I replaced my pump and paid no attention to the subharness inside the tank. If I made turns to quickly or hit a particulary bumpy road, the bad connection in the harness would cause my fuel pump to lose power.


Another thing, you say you replaced the coolant temp sensor. Which one did you replace? There is two on your car. One on top of the engine, and one in the passenger side cylinder head. One feeds the computer info, the other is for the temp gauge. Don't remember which is which at the moment. but if you didn't change the one the computer reads off of, then it could be telling the computer to load it up with fuel, requiring you to press the gas a little to help get a little more air to offset the extra fuel.

Lastly, how does the fuel coming out of the injectors look? Does it spray in a nice cone?

EDIT: Almost forgot! Have you checked the map sensor or its vacuum line at all?

Hopefully one or more of those things above help narrow it down a bit.

Re: Car won’t start unless I press the gas
 

TBI does not retain pressure. No, don't waste more time with that.

I didn't ask about using a paper clip, and "codes" are not the data stream.

Re: Car won’t start unless I press the gas
 

It usually is about 1/2 a tank or below. Only left turns it feels like. Bumpy roads have no issues, although, it makes my dash sound like it’s about to commit suicide.

I replaced the one on top. Didn’t know there was another one

It comes out as a cone. I just recently rebuilt the entire TBI and also cleaned the injectors.

I’ve been trying to find vacuum leaks, but I can’t find one. I haven’t checked MAP sensor. How do I check it tho?

Re: Car won’t start unless I press the gas
 

I double checked since my last post, and yes you changed the one for the ECM. The one in the passenger side cylinder head is for the temp gauge.

Okay good, that eliminates another variable.


The easiest way I know of to check the MAP sensor, is to unplug it and start the car up to see if it makes any difference in how it runs/starts.
It would also be a good idea to unbolt it, take the vacuum line off of it, and see if there is any gunk or such that you can see from looking into the vacuum nipple. If it is dirty you may get by with some MAF sensor cleaner, but would be a good idea to replace it.
Of course it would be a good idea to inspect the vacuum line for it also, it should go to the rear port on the TBI.

Re: Car won’t start unless I press the gas
 

Okay. I’ll look at it. Thank you.

Re: Car won’t start unless I press the gas
 

Today was the first day I’ve driven the car in a month or so. It started right up with no gas or anything.

Weird thing is that it went back to what it was doing, so still tryna find the problem. I still gotta take a look at the MAP sensor

Re: Car won’t start unless I press the gas
 

How do I upload a video on here? I pressed the paper clip attachment button but it wont work :/

Re: Car won’t start unless I press the gas
 

It might be easier for you to upload it to youtube and post a link to the video

Re: Car won’t start unless I press the gas
 

That’s what I thought. I can upload a video tmo and hopefully someone who has ran into something like this can help me.