1988 GTA 305 TPI Hard Starting - Third Generation F-Body Message Boards

JeffD · 08-28-2005, 09:04 PM

Anyone,
I recently purchased a '88 GTA and immediately noticed that in the morning or after the car has sat anywhere for lets say over 30 mins it is hard to start. The engine will turn over and over and acts like it is not getting spark or fuel; however, if I floor the accelerator the engine will start up almost immediately. At that point I am getting a noticeable gas smell from the exhaust almost like the engine was/is flooded. Anyone had any experience with this and/or have some ideas? I just would not have guessed having to even touch the gas pedal in a TPI engine!! The previous owner told me he had the same issues, but that it would start fine in cold weather (won't be able to confirm that for another couple months here...South Carolina).

Help!
Jeff

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mopain · 08-28-2005, 09:58 PM

other than hard starting does the car run fine

87zjeff · 08-28-2005, 10:53 PM

i'm having the same issue. mine is because the fuel system is bleeding pressure. i am assuming mine is from a bad cold start injector/valve. it is the only thing that is the original factory part and the only thing i haven't checked on mine. i checked everything and this is the last thing i can't check. you might find the problem somewhere else but your symptoms are just like mine.

JeffD · 08-29-2005, 05:59 AM

Yes, other than the hard starting it does run good.

IROCThe5.7L · 08-29-2005, 06:06 AM

Leaking fuel injectors or a bad fuel pressure regulator. I'd put my money on the injectors.

mopain · 08-29-2005, 09:19 AM

injectors are a good bet. i just had to replace 5 of mine because the tips were cracked.

Zepher · 08-29-2005, 01:04 PM

FYI, when flooring the accelerator on a TPI car while trying to start the engine (TBI may be the same) the injectors won't fire. this is a feature of the ECM when the engine floods.
Found this out a couple of months ago while I was reading th e service manual I ordered from Helms.

IROCThe5.7L · 08-29-2005, 03:27 PM

Quote:

Originally posted by Zepher
FYI, when flooring the accelerator on a TPI car while trying to start the engine (TBI may be the same) the injectors won't fire. this is a feature of the ECM when the engine floods.
Found this out a couple of months ago while I was reading th e service manual I ordered from Helms.

Yeap. My engine would be flooded after sitting 20 + min. Holding the accelerator down while cranking would make the car start much faster. I'm guessing because it was not dumping fuel into an already flooded engine.

JeffD · 08-29-2005, 05:30 PM

Now if it is the injectors...what is the best way to go about checking them? I don't exactly have $300-400 to throw at a possibility. The better I can narrow this down the better. Does anyone have some suggestions on this? Anyone done this before?

Thanks a bunch!
Jeff

IROCThe5.7L · 08-29-2005, 06:31 PM

Quote:

Originally posted by JeffD
Now if it is the injectors...what is the best way to go about checking them? I don't exactly have $300-400 to throw at a possibility. The better I can narrow this down the better. Does anyone have some suggestions on this? Anyone done this before?

Thanks a bunch!
Jeff

Well first I would check your fuel pressure regulator since it is the easiest. Just pull the vacum line off of it and look/smell for gas.

As far as the injectors, I took off my intake, unbolted the fuel rail and lifted it up so I could see the injectors. I then primed my pump and watched four of my eight injectors drip.

I'm sure you could also pull some of your plugs after it sits a while and check if they are wet with fuel.

mopain · 08-29-2005, 08:45 PM

if the original injectors are still in the car, the will have a plastic like tip on the end. look at the tip to see if it is cracked. shouldn't be hard to see.

GOY · 08-29-2005, 08:51 PM

Put a pressure guage on that fuel rail. Run the car until it's warm, then shut it down and watch how quickly the pressure drops.

I'd feel confident in doing injectors and leaving any further diagnoses alone. If you can smell a strong gas smell, with no start, the injectors have got to be leaking. If fuel was leaking back to the tank (bad valve in the pump head), then you wouldn't be smelling the fuel. The fact you can start it by introducing large amounts of air suggests to much fuel to ignite the mixture under normal conditions, not the other way around.

But that's

Red Devil · 08-29-2005, 10:59 PM

Quote:

Originally posted by GOY
Put a pressure guage on that fuel rail. Run the car until it's warm, then shut it down and watch how quickly the pressure drops...

I'd bet on that 9th injector, I've seen a slew of them go. Can't remember if the '88s had multecs or not, I know the '89s did. If you have those POS injectors I'll bet dollars to donuts (so long as GOY don't steal 'em

) that they've already crapped out.

GOY · 08-29-2005, 11:13 PM

Quote:

Originally posted by Red Devil
donuts (so long as GOY don't steal 'em )

Since Coc tends to kill your appetite, I guess I'll have to eat them Red Devil, sorry. Get off the junk and maybe I'll share. That is if you can stop talking long enough to get one in your mouth.

(Pretty sad, now you are going to follow me from thread to thread, humping my leg to try to get a "Burn" in.

, but please make them original.)

Red Devil · 08-30-2005, 10:39 AM

Thanks for the nice personal attacks GOY!

Take the twig outta your ***. I made a joke, (and a universal one at that) not my fault you are a sore loser. Were I you I'd stop slinging the baseless personal attacks and circumventing the board spell checker. Or better yet keep it up, I'm sure the mods must be fully enjoying seeing you calling me a crack head and wanting to stuff my mouth with your pecker.

What little credit I had given you just dissolved away. Grow up. If you can't stand losing a debate, don't debate or go get some education in it to better yourself at it. If you want to hang out with 5 year olds feel free to keep practicing Name calling 101.

JeffD · 08-30-2005, 04:59 PM

Thanks guys those are great ideas and I will be checking on this as soon as possible. I also noticed the other morning that I had a puff of blue smoke come out the exhaust when I first started it. How difficult is it to pull the intake and rebuild the heads (specifically replacing the valve stem seals)? How long should I plan on to do this job?

Thanks a bunch!
Jeff

mopain · 08-30-2005, 10:46 PM

it shouldn't take to long to do. i have a four day weekend this week and i'm doing the same thing to mine. as long as you don't have to take it to a machine shop for any work you could have it done in a day.

if you do take it to a machine shop it really just depends on how long it takes them to finish their work.

good luck

JeffD · 09-03-2005, 05:14 PM

Quote:

Originally posted by GOY
Put a pressure guage on that fuel rail. Run the car until it's warm, then shut it down and watch how quickly the pressure drops.

I'd feel confident in doing injectors and leaving any further diagnoses alone. If you can smell a strong gas smell, with no start, the injectors have got to be leaking. If fuel was leaking back to the tank (bad valve in the pump head), then you wouldn't be smelling the fuel. The fact you can start it by introducing large amounts of air suggests to much fuel to ignite the mixture under normal conditions, not the other way around.

But that's

Ok so I hooked up the pressure gauge and when I turned the key on and pressured the system the gauge went to 40psi. Turned the car on and it ran at about 37-38psi. When I shut the car off the pressure went back to 40psi. The gauge noticeably went down and was at 0psi in under 5 minutes. Thoughts anyone?

Jeff

IROCThe5.7L · 09-03-2005, 06:48 PM

Your pressure is bleeding off way too fast. Do you have an adjustable fuel pressure regulator?

Here is my my pressure vs time when I had four leaking injectors:

JeffD · 09-03-2005, 07:13 PM

Quote:

Originally posted by IROCThe5.7L
Your pressure is bleeding off way too fast. Do you have an adjustable fuel pressure regulator?

Here is my my pressure vs time when I had four leaking injectors:

Hey IROC. Wow!! I would say mine was bleeding off way too fast also!! I thought maybe the system wouldn't hold pressure and just bleed back to the tank. I guess I am wrong. I am not sure if my fuel pressure regulator is adjustable or not. All I can see right next to my gauge connection point are basically two vacuum lines that go to the regulator. How would I know if it is adjustbale or not?

Thanks!
Jeff

GMTech · 09-03-2005, 07:16 PM

I am agreeing with the others on one or more injectors leaking. All it takes is a small amount of deposits to cause the pintle to hang open.

Like the others said, take off the plenum and unbolt the fuel rail. Support the rail so the injectors are no longer in the lower intake and prime the fuel system. If any inejctors spray or drip, they need replaced. If you have the cold start injector, don't overlook that either.

JeffD · 09-03-2005, 07:46 PM

Thanks for the input GMTech. Question for you though: what is a cold start injector?

Jeff

GMTech · 09-03-2005, 08:17 PM

If you look at the picture below, you'll see I circled where the Cold Start Injector would be, on an equipped car. If you have an injector mounted in the runner where I circled below, then you have one.

It was used to spray additional fuel into the intake during cold starts. It was the fuel injection version of the carburator's "choke". As technology advanced, engineers discovered instead of adding a "cold start injector", they could just hold the original 8 injectors open longer on a cold start to get the same effect, and therefore was removed in later model TPI's.

burnout88 · 09-04-2005, 10:41 AM

Sounds like the injectors are leaking to me. Just an FYI Ford 19lb injectors will work fine. That is what I put in my car as a replacement and they are much less prone to leaking. I picked up a set used from a 5.0 mustang guy with 35K on them for 25 bucks.

A lot of mustang guys have good stock set's just lying around. Often they upgrade there injectors more frequently then TPI people. (Easier for them to do).

IROCThe5.7L · 09-04-2005, 05:48 PM

Jeff, you can also send your injectors to rich@cruzinperformance.com. He will clean and flowmatch them. He does great work.

GMTech · 09-04-2005, 06:15 PM

IROCthe5.7L, thats an excellent graph. You should make a new one, now that you no longer have the leakdown, for comparison sake. We all know that residual fuel pressure doesn't last forever, even on a "good" system, so it would be interesting to graph a known good leakdown rate.

JeffD · 03-19-2006, 05:52 PM

OK. I replaced the injectors with some Accel injectors recommended in another post I have in here. The process was fairly straight forward except for a few things:
1) the bolt holding the fuel lines to the block just forward and below the water thermostat housing was an absolute pain to get off in order to remove the fuel lines to get the fuel rail lifted up. It might have been easier to remove the alternator in order to have better access to it.
2) buy gaskets for the air plenum, plenum runners and the thermostat
3) A shop vac is handy to remove any debris that gets in around the intake and even while you are cleaning off old gasket material it is a blessing if some material actually falls in.
4) A universal socket to handle the torx bolts under the runners and especially near the firewall is a must (some masking tape for an extra measure of safety wouldn't hurt either!)
5) REMEMBER to remove old o-rings out of fuel rail prior to installing new injectors...the injectors will go in with two o-rings in there! 6) The fuel takes a little encouragement to come out...just slowly work it back and forth and the entire assembly will "pop" out
7) Take a digital photo of things as they were PRIOR to disassembly and along the way...this can assist with where everything runs i.e. electrical wiring for the injectors and vacuum lines
8) Draining some coolant out prior to removing upper coolant lines will avoid any coolant from spilling out on to the intake/injector areas
9) Air plenum and runners will become a little "united" over time i.e. metal gaskets adhering to either side, so they will take some gentle persuasion to separate...just keep in mind they are aluminum and the runners are thin so don't go banging on things
10) The job takes about 6-7 hours to do assuming you don't run into anything major or something else that needs to be repaired or replaced in the process. I did it in just over 6 1/2 and that was with fighting the fuel line bolt I mentioned earlier

The end result is that the car fires over like it was right off the lot...no more 5 second turnovers with heavy gas fumes out the tail pipe! Fuel rail pressure bleed off is also very much improved i.e. no more leaking injectors. Originally my 42psi was bleeding off to 0 psi in under 5 mins. Now my pressure is 42 psi after the system is pressurized and is still at 32 psi after 2 hours. Not bad! Thanks to all of you who gave me pointers in doing this. Valve stem seals are next!!

Jeff