I've searched all over the threads for this issue but only found posts about cars equipped with a cold start injector which I don't have. I have an 89 350TPI. On cold starts after 5-8 seconds of cranking the car eventually starts and any time during the rest of the day it starts right up, it does this pattern every time. I hear the fuel pump prime every time I turn the key. Can you have a bad fuel pump relay and still get primed with the turn of the key? (Also for the injectors to pulsate I believe you are supposed to get a signal at the end of every spark from the ignition module, so if the ignition module was bad they usually act up when they are hot not cold.) The car does have a little bit of a gas smell, then again the cats are out. The SES light has not thrown any codes of running rich, I wonder if that has anything to do with the long cold starts. Can someone shed some light on the long cold starts and why it starts right up anytime after the initial cold start? The car runs great after I start it, no hesitation or idle surging. Do I need new injectors or fuel pressure regulator maybe?

 

A list of things you have replaced will help us help you.

Im battling this issue myself. Its super annoying I know. Have you done a tune up or replaced anything to rule it out? Do you have a Voltmeter or a fuel Pressure gauge? Sometimes, codes won't be thrown if things are bad like the o2, you will just run really rich. With a voltmeter, check the TPS and injectors. My TPS was set low .48 idle, I bumped it up to .54 and noticed a better starting but it's still not perfect. I cleaned the IAC and TB that helped a bit too. My list of things to check is getting pretty bare now. All thats really left are the expensive things, MAF, ECM, Injectors.

 

Tune up was done less than 10k miles ago, new cap, rotor, spark plugs/wires, msd 5 blaster, throttle body has been cleaned, new air filter, even a whole new set fel-pro intake manifold seals and plenum/runner seals, so there are no vacuum leaks. IAC should not effect how the car starts, but how it idles. Timing is set to 6 degrees as it says on the sticker under the hood.

- I checked the TPS voltage tonight and it was at .56V (the spec is .54V +/- .075V).

- I ohmed out the injectors with a very accurate volt meter and got the following:
16.2, 11.7, 16.0, 10.3, 11.8, 16.2, 16.0, 16.0
The spec in my Haynes manual says 11-14 ohms but people on the forum say 12-17 so I don't know if the injectors are OK or should be replaced. I also primed the car and then unplugged the vacuum line into the fuel pressure regulator to see if there is a leak in the diaphragm (is that one way to tell or do I have to start it then check?)

I know there is plenty of power in the car and good throttle response but long cold starts and gas smell from the exhaust (you sure it's not because the cats are out? I know the exhaust should smell worse without cats so not sure on that one). I do get the blue smoke on start up after it's been sitting for a while, probably from needing valve seals but during the day sometimes it will smoke and it still starts right up, so I'm going to rule that out. I also read something about a fuel pump pulsator and something about the carbon canister for the fuel. I never did change the O2 sensor, I thought I would be getting a code thrown if the O2 was sensing rich or lean.

What do you think, injectors or not? What do you think I should do next?

 

Anybody?

 

If your car has the stock injectors, they could very well be your problem. The best thing to do is to attach a fuel pressure gauge to the Schrader valve on your fuel rail, and check the fuel pressure, which ought to be fine if the car runs normally.

What you will look for is whether or not your injectors are leaking down. If you turn the key on, the pump primes, and you should see about 40+ psi. If this bleeds down quickly, your injectors or your FPR are likely at fault. This would explain the hard starting, and the fuel smell.

One way to verify this is to mash the pedal to the floor when cold starting. If it starts more quickly, then you have a 'flooded' engine. You can tell if the FPR is leaking by removing the vacuum hose. If fuel drips out, your diaphragm is pierced. If not, your injectors are probably leaking down.

If they are, replace them with Bosch III's... I recommend southbay -- I got a complete set of reconditioned injectors and all necessary gaskets for around $160... yours will be more because I have a 305 and the 350 injectors cost more.

One thing I will say: after doing a lot of research, I have learned that the OEM injectors are far inferior to the Bosch III's, so you should see some benefit from going to them.

 

Two things to try. I've replaced about everything on my 89 and no help yet. But I notice that I can start the car a couple different ways that seem to help. Try hitting the starter for a couple seconds, let off, wait for the fuel pump to shut off, wait a couple seconds, then hit it again. If no help try turning the key to start real quickly when cold starting, don't wait for the fuel pump to run and build pressure. This actually works better for me, maybe six or eight revs and it fires off. The 89 actually is programmed to not start right off anyway from what I've read on the Corvette forums. It's supposed to roll over 8 revs to build oil pressure or something. Sure gets aggravating though.

 

This also something you can check, my car is a 92 gta L98. I had a problem like what you are talking about. After alot of checking and new parts I started to check the wires. I found that the wires to my temp. switch that goes to the Ecm had rubbed and touched each other. when this happens the Ecm thought the motor was already warm so it wouldn't start right when it was cold. (warm it would start ok.) It didn't put on a check engine light. Once I separated the wires it started to work right. I don't know if this will help you but It fixed mine. Just thought this would be something you can check. Hope this helps.

 

OK I ordered new Bosch III's and an adjustable FPR from TPIS. Last night I checked the vacuum hose on the fpr and no fuel was coming out of it, which is a good sign. Rob, which temp switch are you talking about, the one on the front of the intake manifold under the throttle body?

If this was true then it should have a delayed start every time even when the car is warm, correct?

 

Have you checked fuel pressure when this problem occurs? Also inlet air temp sensor and coolant temp sensor. BTW, IAC does control sartup air to the engine. Try the first cold start with slight openning of the throttle. If the engine starts easily, the problem may well be IAC related. Clean the throttle using carb cleaner, a small bore brush and a cloth. Perform minimum idle air adjustment procedure and IAC relearn. I will not attempt to detail these procedures in this post but you may find them by searching the tech board on this forum, or in the factory service manual.

 

Thanks doc, I will try like you suggested with the slight opening of the throttle upon startup, I believe I already tried that with no noticeable difference but I will try it again to make sure. The throttle body has already been cleaned thoroughly. The only thing I haven't done is the minimum idle air adjustment. (I did just recently put in a T56 from a 700R4 about a week ago but this problem is way before that)

 

Dont know why I didnt see it before, but you have two bad injectors. You say the car starts and runs fine after the first cold start each day? Your description doesnt sound like injector issue but you will want to address your injectors soon. Buy a blueprinted set. Bosch are the best.

 

Yes the car runs just fine, no hesitation. What are your recommendations doc? I already purchased a set of bosch iii injectors but anything else?

 

Check fuel pressure and decay rate. I recommend you do this after youve replaced your injectors. You dont want the results fouled by a leaky injector. Connect a pressure gauge and cycle the key until max pressure is acheived. If pressure is slow coming up, you may find it easier to start the motor, disconnect the vacuum from the fuel pressure regulator and shut the motor down. After the fuel pump stops running, pressure should drop slowly. The general rule for replacing a fuel pump is a drop of pressure to zero in under 20 seconds.

One thing that can cause a long crank and is often overlooked is the fuel pump relay itself. The fuel pump is normally powered by the relay until the oil pressure switch closes at about 4psi. On a cold start, with no power from the relay, the engine may take several seconds to build sufficient oil pressure and subsequent fuel pressure to start. After the first start the engine will be primed with oil and the fuel rails primed with fuel so that the engine may start faster on subsequent attempts. The above test for fuel pressure drop will show a bad FP relay. The pump should run and fuel pressure should come up when the key is turned on. If not, the relay or control circuit is bad and needs to be diagnosed and repaired.

 

Thanks doc. I am starting the injector replacements tonight. The fuel pump primes when I turn the key and I can hear the relay every time. I know that the oil pressure switch is in parallel with the FP relay so that if the FP relay was bad when 4psi was achieved it will power the FP. Sadly it was not as simple as this in my case. I will replace the injectors and report back. I am putting in an adjustable fuel pressure regulator while I'm at it. What is the recommended fuel pressure for the Bosch III (22lbs) so they atomize properly? TPIS says start at 47psi (which is not stock), Jon from fuelinjectorconnection.com recommends 50psi...Also I tried pushing in the throttle about 1/2 way while starting and it took longer that way.

 

If 1/2 throttle didnt help and fuel pump is priming with key on, definitely sounds like injector issue. 22lbs is the same rating as factory. I would set pressure just where factory pressure was, about 45-50psi. Once she's running, you can fine tune FP to acheve neutral BLM using a scan tool. Neutral BLM is 128.

 

ASE doc, can you recommend a scan tool for me? (I was thinking of the xtreme aldl from moates with tuner pro rt software). If there is something more user friendly and portable, I am open to suggestions.

 

Im not familiar with tuner pro sotfware. I dont believe you can make any program changes to your ECM through the ALDL to begin with unless you make hardware changes. The scantool I most recommend for the 3rd gen is the Snap On MT2500 "brick". Its very durable and will read codes and live data as well as any other machine. Plus they have "Troubleshooter" with common fixes for most DTCs. They sold new for $2500. Now they are available used for $300. Verify that the one you buy has the GM-1 interface w/power cable and domestic software. Also verify its operation before you close the deal.

 

I don't want to make any changes to the ECM I just want to read live data without spending too much. Any other scantools that will do the job for cheaper?

 

A few years ago, everyone made scan tools for the OBDI GMs. Now they are few and far between. The tough part is the interface. The 12 pin GM ALDL is unique to select GM model years(82-95). Of course, almost any generic scan tool from that period will work fine. However, many of them were cheaply made and may be in bad shape by now. $300 is really not a bad deal at all. Post a thread on the DYI PROM forum. RBob is the moderator over there and he's pretty sharp on everything ECM. He may have some better answers for you.

 

ASE doc, I also forgot to mention I always have a good amount of pressure build up when I take the cap off the gas tank that I can actually hear, if that provides any insight to anything (check valve etc). Also do I really need to scan for BLM or can I just put the afpr pressure where it is originally on the current fpr?

 

You can just set it where the factory unit is. However, its an aftermarket part and may function slightly different. Thats why I suggest using BLM to verify factory AFR.

The pressure in the tank may be an issue with the purge system and tank vent valve. However, its more likely this would cause problems on hot starting than on your first cold start everyday.

 

ASE doc, I took some fuel pressure measurements before I started any work. When the pump first primes, I have 38psi from the schrader valve then it drops slowly maybe in a minute or more to 15-20psi and gets real slow from there. When I primed it again it went back to 38psi and just stayed there. When the car is running and the vacuum hose is disconnected, I get a steady pressure of 43psi. With the vacuum connected, it is 33psi steady. I just started working on it last night. Here are some pictures of where I am at right now. Just need to loosen the 4 bolts on for the rails and the fuel lines and they should come right out. Do the new injectors "click" into the intake manifold like the old ones? I also heard that you don't re-use the old injector clips?

 

The clips retain the injectors in the rails for assembly purposes. They are not necessary but you can install them if you like, makes no real difference. Be sure to lube the injector o-rings with vaseline or equivilent to ease assembly and prevent damage and a subsequent leak. Be sure that manifold/injector bungs are thorouglhy cleaned of any dust or debri and that no o-rings are left behind from old injectors.

 

I usually just use motor oil to lube the o-rings, will that be ok or should I really use vaseline?

 

Motor oil works okay but its a little thin. A light grease, like vaseline, does better to prevent tearing an o-ring. However, years ago, I used to use ATF and never really had a problem. It was suggested by an injection expert I know that vaseline was better, so I started using it.

 

I know now I'm sounding picky. What about all-purpose white lithium grease? (I don't think I have any vaseline) Do I put the grease on the fuel rail end as well or just intake manifold end?

 

White lithium grease should be fine, as long as its not too heavy. I have white lithium assembly lube that would work. Apply it to both o-rings on each injector. The petrolium base of the grease will dissolve quickly in gas. So its okay of a small amount gets into the fuel stream. Just dont heap it onto the inlet end of the injector.

 

all this useful info howdo you check to see which injector(S) are good.bad?

 

ASE doc, I put the new injectors in and afpr, when I primed the car one of the injectors leaked from the top (rail side) after I had bolted the rail already to the manifold. So I wiggled that injector up and down and left and right and the leak was gone. I primed it 4 or 5 more times to make sure. Should I worry about anything you think and take the rails and injectors out to make sure? (Please say no ) Here are some more progress pics below.

Take a volt meter and measure the impedance across the 2 pins of the injector to see if it is within 12-16ohm range.

 

I too have an "eternal cold cranking" F-body. Very interested to see how this ends, so don't give up.

I have an 89 L98 in my car, and new Bosch III's, but the problem still lives on. Swapping the injectors didn't fix my problem, but hopefully it fixes yours. I have yet to swap the FPR, but my FP is right on.

I had a thought though. This problem could be in the PROM. WHat kind of chip do you have? I had a similar issue with my 87 GN. I got a custom chip burned and it went away. What do you think about that?

 

The ECM is stock, no after market chip or anything. My fuel pressure was right on with the old regulator but I wanted to have the option to change it for future mods or in case these injectors needed a little higher pressure. I will set it back to stock 43.5psi when it is running. Right now I am worried about that injector leak that I solved by wiggling it all around as an attempt to re-seat the injector. I really hope that that's all it was. I called fuelinjectorconnection and they said it was common and just probably the o-ring got snagged to one side a little and as long as it's not leaking now when I prime it (which I did prime 4-5 times with no leak), then I should be fine. Also can someone verify what the torque specs are for the runner tubes to plenum and runner tubes to intake manifold. My Haynes manual says 18ft-lbs but I could have swore I read 25ft-lbs somewhere here on the forums?

 

double post.

 

I'm sure the leak was an o-ring that wasn't seated. If it doesn't leak now, you should be good. What do you have left to complete before starting it back up?

 

I need to put the runner tubes, plenum, vacuum hoses, throttle body, throttle cables, clean some things up, top off the coolant (because I changed my t-stat from 160 to 180 while I was at it, 160 is too cold). Torque everything to spec and start her up. I think I might finish tonight, I think. I'll take more pictures along the way.

 

Hmm. The leak is unusual. I either have them leak because oif a bad o-ring or not leak at all. I never have them leak for a minute then stop. However, its your car you and your work, you have to decide whats okay. If its not leaking now it may be fine. Maybe drive it for a week, checking it each day. If it doesnt leak in that time, its probably okay.

 

It didn't leak and then stop. It leaked until the fuel rail pressure dropped to zero. When I saw that happen I wiggled the injector in all directions to try and re-seat it. Then when I primed it again (4-5 times), it didn't leak at all. So it was probably just not seated correctly, right? (I also did notice that the fuel pressure drops quicker when the pump is done priming than it used to, maybe it's irrelevant?)

 

Oh yeah, I understyood what you meant. That it stopped leaking after you wiggled it. Again, thats not what Im used to seeing. Just watch for it to leak again. If it doesnt then cool.

 

What about the fuel pressure dropping quicker than it used to? I think it drops somewhat quick to 20psi and stays there for a minute or so then to 0.

 

Also, do I re-torque the runner tube bolts after I've driven it and let it heat up or just once during re-assembly?

 

Make sure you have the correct year PROM. Seen that cause a hard to start while cold plenty of times in 1989 cars. It HAS to have a 1989 PROM.

 

Where did you get your injectors? One or more may be leaking. Try running it and see if it improves after its warmed up a few times. The runner gaskets seat fine without retorquing.

 

I finished putting it together tonight and I wasn't too happy. I triple checked everything. When I first started it, it had a hard time staying on, so I gave it a little throttle, and it cleared out whatever throttle body cleaner I had sprayed to clean the throttle body and runners. I drove it around and every time I pushed the gas the car felt weak and hesitated. When the RPMs climbed it got a little better but it was lacking power. So I checked the pressure and it was 40psi without vacuum. I increased it to 43.5 (stock setting) and it got a little better but still hesitated. I increased it to 47psi like the TPIS instructions say and it got better but still a little hesitation. So I increased it to 50psi like Jon from fuelinjectorconnection suggested when I first bought the injectors and it got even better but I can still feel a little hesitation. Also my idle has increased to 900rpm which I definitely don't like (used to be 550). ASE doc, what should I do? What is going on? How high do I bring the pressure up to get rid of the hesitation? And at the same time what do I do about my idle? Why do the new injectors need higher pressure? I'm starting to regret changing the injectors. The car ran fine besides the longer cold starts before all this. I'm depressed...I did take out the IAC motor and clean it out since it was kinda black. While the IAC motor was out I plugged it in and turned the key to ON only and the pintle didn't move, is it suppose to or only when the car is on? Then again it was fine before I did all this work...

 

There is one thing I did notice, the new throttle body gasket was a little different than the old one. I attached a picture of the old one and the new one. Do you notice how the little triangle section between the two butterflies where the IAC motor sucks air from is blocked off with the old gasket? The new gasket has a little triangle cut out so it's open. Does this have anything to do with the part throttle hesitation?

 

That sucks. Sorry you are having a hard time. I have 22lb Bosch III's and a stock fuel pressure reg. on my car. The fp is 40, line-on. I highly doubt the fuel pressure is your problem. With these injectors, my stock L98 runs perfect (except the long cold cranking). Shouldn't be any different for you.

- Check really closely for vacuum leaks. How did you tighten the runner bolts? Get a couple of cans of starter fluid and spray around for vacuum leaks.
- Is there a code or black smoke?
- The IAC will not move unless you jumper pins A and B on the ALDL, or if the car is running.
- Adjust the FP back down to 40-43.5.
- I would go back to the original gasket.

Let me ask you this. Is it cool/cold outside where you live?

 

By the way, don't get so discouraged. Your car WILL run good... great with those injectors. FIC is the best in the business too. I'm sure they will make it right ff there is a problem with the parts (which is HIGHLY unlikely). There is just something not right with the set-up. You'll find it, just take your time and don't stress. We will try to help, too.

 

I greatly appreciate your help and support. If you want to contact me by phone, send me a PM.

- I tightened my runner bolts to 18ft-lbs with a calibrated torque wrench (still new). Everything was tightened to 18-ft-lbs.

-There are no codes or black smoke. The car actually fired right up this morning, but last night as I said before it was hesitating with little load on the car until the rpms get up a little from idle. It is idling just fine, not searching for idle or anything, just a little high now ~900rpm.

- I will adjust the fuel pressure to 43.5 (no vacuum) and 33.5psi (with vacuum, is that low normal?) like it was before I did this work. Although I noticed the car much more "normal" feeling and responsive like my old injectors when I had the new afpr and injectors set to 50psi. Why is that? Even when it wasn't hesitating, the car felt weak at higher rpms with the stock pressure and much more pull at 50psi? What are your thoughts on this? If it was just an IAC problem, would that effect acceleration all the way through power band and make the car feel weak?

- I will check for leaks this weekend or today if I can. But how could there be a leak? I cleaned all surfaces very well and new gaskets all around, I've changed the runner tube gaskets before with no problem. Can I use aerosol Sea foam injector cleaner, it's not as volatile as carb cleaner so will it still reveal a vacuum problem?

- There is one thing I'm wondering...what if my old throttle body gasket was hiding a IAC motor problem the whole time by blocking the air inlet with the old gasket. Now that I have a new gasket with the triangle cut out, the IAC is getting the opening it needs and now the IAC motor problem is revealed? Does that make sense? By the way I started the car up this morning and it started right up, no cold start delay, but now I have these new issues...

- I live in MA, mid 50s-60s temps.

 

The gasket idea is possible, I suppose. Check/adjust your IAC and TPS. At the very least you will know that it's set right.

Your vacuum leak could be coming from a vacuum line either disconnected or broken. There are atleast 3 lines. There is a vacuum line junction next to the coil on the intake manifold. Check that as well.

 

When you say check the IAC, you mean take it out and measure flange to end of pintle length to make sure it's 28mm? or do you mean jump A and B on the ALDL and check for clicking to make sure it work? The junction of vacuum lines near the coil with that weird vacuum splitter are fine, I checked those already, no cracks, and the plastic hoses from the EGR to that plastic unit near the bottom of the distributor is fine too, and the one that goes to the bottom of the throttle body. I'm running out of vacuum lines here guys...anymore to check? I will unplug the battery and let the computer clear itself of any learned coefficients and adjust the pressure back to 43.5 and drive it again. The Haynes manual does say 34-47psi is the spec, mine was 43.5 before I touched anything so you sure I should put it back there? I spoke with Jon from fuelinjectorconnection and he said the car ran better when I upped the fuel pressure because too much air was getting in from somewhere (vacuum leak) and when I cranked up the pressure I compensated for that...sound right?

 

OK, I checked all the torque on the bolts and they were fine, sprayed some fuel injector cleaner around the gasket area and the idle didn't change and on the vacuum hoses. There is no vacuum leak that I can find. I brought the pressure back to 43.5 and it's really not hesitating anymore. I did unplug the battery to clear the memory of any BLMs saved that is if they do get saved...not sure if that helped or not. but I paid closer attention, the only time I really feel a very slight hesitation and I don't mean pinging or anything is just from 500-1000 rpm when under load. The idle is at 850-900 rpm, probably from using the correct gasket now. My question is: should I adjust the idle and bring it down to 550 like it used to be and then adjust the TPS after, would that help anything? Also at idle the timing was 6 degrees I checked it again.

 

Sorry for the delay getting back with you. Ive been busy at work today. I agree you need to check for vacuum leaks. The best thing to use is aerosol brake cleaner. Its cheap and non flamable and it will reveal a leak quite well. The difference in the TB gasket looks strange I know but if you look closely, they really do seal just the same. The one has the triangle opening where the other just has an open area. You cant put the gasket on backwards because it only goes one way. If your IAC was blocked off, the car wouldnt idle.

I really wish you had access to a scanner right now. Integrator and Block Learn will show you how lean you are running. You do have a volt meter though. Use it to monitor O2 voltage by disconnecting O2 sensor and attaching volt meter + lead to sensor side of connector. Youll see the voltage rise or fall with fuel mixture. In this mode, BLM and integrator will go neutral with the sensor disconnected. The voltage you see is the uncorrected fuel air ratio. This test works well for finding lean or rich conditions.

Another thing to look at, did you reset the fuel adaptives after changing injectors? Reset adaptives by disconnecting batt- for 30 seconds. Stealth mentioned IAC setting. You cant actually set IAC or TPS since they are both non adjustable. You can however set base idle. This can have a significant effect on fuel correction. Your manual should have instructions for setting idle.

In case your manual doesnt have the procedure. Here's a quick run through. In order to set base idle, you first need to access throttle stop screw. If the plug is not already out, you need to remove it by piercing it with a sharp awl or drill. Then pop it out by carefully prying it. Set base idle in the following manner: jump terminals A & B of the ALDL, disconnect the timing connector, turn the key on and wait for 45 seconds, disconnect the IAC, then remove jumper from ALDL. Start the engine and allow it to go into closed loop, set idle to 450rpm. Turn off key, reconnect timing connector, reconnect IAC, reset ECM by disconnecting batt- for 30 seconds.