Takes a long time to start after sitting in the cold weather ---

[alwayscode390]

Here is a vid of my car in 35 degree weather starting after sitting for a day. Takes about 4 seconds of turning the starter.

http://www.youtube.com/watch?v=JrulW0XEWGY

I just went and started it after 6 days ... and it took about 6 seconds. I just about let off the starter before it kicked over.

After its been running , it will start in 2 seconds ... what I would consider normal.

The last owner warned me of this, and said its ok.

Im not really worried about anything but the fact that this cant be easy on the starter ... and I have been warned that the starter being under the intake manifold is an expensive / long job.

How strong are the starters? Is this normal behavior for our cars? Any advice you can give me?

---Car has 43k miles, New Injectors/fuel pump/pump regulator, 1990 ZR1 LPE Ported Package---

Thanks :) ---

[scottfab]

Normal.

[Blue Flame Restorations]

This hasn't been the case with my Z. It's been sitting outside because the shop and house garages are full at the moment.

Mine starts just as normal as when in the cold as it did in the warm months. Six seconds is a pretty long time. Mine fires quickly all the time. Sometimes as instant as the key is turned.

ADDITION
My statment above is AFTER I let the fuel pumps energize the fuel rails.

[Fully Vetted]

When you first turn on your key you will hear the fuel pumps start. Try waiting a few seconds before you engage the starter. I know it made a difference with my car.

I remember seeing your video of you starting your car over on CF and I didn't think it was going to start.

[Paul Workman]

Well, 6 seconds seems a bit on the long side. Mine is about 3-4 seconds AFTER the fuel rail is charged.

Before rolling the ignition switch over to START, turn the switch to the "ON" position and listen to the fuel pumps. When they stop running, the rail is up to pressure, but it takes maybe a couple seconds before the rail (on my 90) is up to pressure. If I roll to the START position before the rail is charged, I can see how that might invite a backfire (NOT GOOD) at the very least. But, also add a second or two to the normal 3-4 second (cold) start time.

Once it has been started and run that day, the start time is much quicker - sometimes under a second!

And, if nobody told you, you want to hold the switch in the START position for almost another second after it fires to let the motor rpm start coming up. This avoids backfires which tend to blow hoses off the MAP and the Fuel Pressure Regulator (for starters) at the very least, or rupture diaphrams in said parts (rare, but happens). This trick might avoid a plenum pull to re-connect a vacuum hose. Just sayin...

P.

[Paul Workman]

When you first turn on your key you will hear the fuel pumps start. Try waiting a few seconds before you engage the starter. I know it made a difference with my car.

Ya beat me toit!;)

P.

[Fully Vetted]

...And, if nobody told you, you want to hold the switch in the START position for almost another second after it fires to let the motor rpm start coming up. This avoids backfires which tend to blow hoses off the MAP and the Fuel Pressure Regulator (for starters) at the very least, or rupture diaphrams in said parts (rare, but happens). This trick might avoid a plenum pull to re-connect a vacuum hose. Just sayin...

P.

Good info. I had not heard this before. Thanks, Paul.

[alwayscode390]

These are DEFINATELY some quirky cars.

I had no clue about letting the fuel pumps prime the rails ... but it makes total sense.

I will see if that helps out my situation.

Thank you all :) ---

[scottfab]

These are DEFINATELY some quirky cars.

I had no clue about letting the fuel pumps prime the rails ... but it makes total sense.

I will see if that helps out my situation.

Thank you all :) ---

You're going to have to get to know your car. It isn't always the case
that you want to wait the 2 sec to let the fuel pressure come up.
Here is why.
1. If your fuel pumps hold pressure well after being turned off then you can go straight to starter, no waiting 2sec for pressure.

2. If your fuel pumps do not hold pressure (excessive and quick pressure bleed off) then is does no good to pressurize the rail since the pressure bleeds off too quickly (yes this probably should be addressed/fixed but if you're not up to pulling fuel pumps right away then read on) This was the last failure I had and going straight to the starter position yielded a faster start.

3. If your fuel pumps bleed off pressure slowly then it may make sense to hold for the 2 secs to get a better chance at the highest pressure.

Here's the deal. I've had my car now for 15yrs and several fuel pumps and have seen all three of the above. To find out how yours behaves you need to attach a fuel pressure gauge to the rail and see.

If the goal is to reach the quickest start time know which of the 3 you have and start accordingly.

One other pointer. It's not a good idea to do aggressive lateral driving with < 1/4 tank. If the fuel pumps suck air it stresses/ages them and can lead to premature failure.
It's another quirk.

[alwayscode390]

Thanks Scott ... you seem very knowledgeable , and I have learned a lot from your posts. I appreciate the help.

I would like to attach a permanent fuel pressure gauge to the rail ... is there enough room for a 1 1/2" liquid filled gauge? I have ran some that attach to the Shroeder Valve in other vehicles. Is it a 1/8 NPT female port on the rail?

What is the typical Fuel Pressure I should look for at the rail?

Happy Holidays!!! :) ---

[Z51JEFF]

Mine fires quickly all the time. Sometimes as instant as the key is turned.


Lately after my car sits for a few weeks it will start instantly,its a little unnerving considering the oil hasn't has a chance to pump up.Marc H says its nothing to worry about so I guess its no big deal just cant understand why all of the sudden its doing this.My first thought was a leaky fuel injector.

[alwayscode390]

Sounds like a leaky injector to me too ---

[scottfab]

... snip...
I would like to attach a permanent fuel pressure gauge to the rail ... is there enough room for a 1 1/2" liquid filled gauge? I have ran some that attach to the Shroeder Valve in other vehicles. Is it a 1/8 NPT female port on the rail?

What is the typical Fuel Pressure I should look for at the rail?

Happy Holidays!!! :) ---

I'd sure be careful about that. Who knows what the vibrations will be at the end of the rail. You get a leak and you're looking at a fire.

Pressure should be ~50psi but it really depends on the brand and age of the pump(s) you have. If you get down to around 40psi you've got problems. There is a special pig tail between the motor and the battery that can be used (with key off only) to test the fuel pressure. I hooked up a permanent switch on it for testing. It keeps the pump running. For a real run down on testing see the FSM.
If you don't have one yet we can help with that.

[alwayscode390]

I have a CPT "LT5 Engine-Mechanical" booklet (white), and a SERVICE MANUAL SUPPLEMENT "1990-1993 Corvette RPO LT5" booklet (red) .

Time to start reading when I can find the spare time :) ---

[scottfab]

I have a CPT "LT5 Engine-Mechanical" booklet (white), and a SERVICE MANUAL SUPPLEMENT "1990-1993 Corvette RPO LT5" booklet (red) .

Time to start reading when I can find the spare time :) ---

So you don't have the regular service manual?

[Blue Flame Restorations]

Lately after my car sits for a few weeks it will start instantly,its a little unnerving considering the oil hasn't has a chance to pump up.Marc H says its nothing to worry about so I guess its no big deal just cant understand why all of the sudden its doing this.My first thought was a leaky fuel injector.


Honestly, it may be timing and compression just by the luck of the draw, so to speak, as the motor is shut off. This happens to me regularly enough.

Yes, it kinda takes you by surprise. I don't like it because I always like a longer cranking time in order to get some oil to the top of the heads, even though I have the check valve in the oil filter. And when this instant start happens, it always seems that the rpms are high initially, as well.

I spoke to both Pete and Marc about it and was told not to be concerned.

I also studied the old Lotus engine build data that I have. Their data showed 5 seconds to build oil pressure upon start-up. This was only one example.

[Z51JEFF]

[QUOTE=Blue Flame Restorations;157736]Honestly, it may be timing and compression just by the luck of the draw, so to speak, as the motor is shut off
/QUOTE]

Its a little odd that this would just start happening now after having the car for awhile now.Something else to take into account twice now in the last couple off months for a few seconds the car wasnt running on all cylinders,felt like it fouled a plug but it cleared up,straightened out.Might be an injector going South.:(Ive got a Haibeck chip and I was under the impression that a touch of extra crank time was programmed into the chip.Oh well,if those in the know said its not a problem,thats all I need to know.:-D

[alwayscode390]

So you don't have the regular service manual?


I guess not ... unless that's the book that most people keep in the car with them. I have a 1990 Corvette book in the glovebox.

What other literature do you suggest that I pickup?

Seems that my start time is not too much to worry about. Do ported engines usually take longer to fire up? It may be the LPE chip too I guess?

Could be the cold weather too , I will see how she responds this summer.

I appreciate it ---

[tomtom72]

First, Jingle Bells!

try this link.

http://www.helminc.com/helm/product2.asp?Make=CHV&Model=CVET&Year=1990&Category=&class_2=CHV&mk=Chevrolet+%26+Geo&yr=1990&md=Corvette&dt=&module=&from=result&Style=helm&Sku=ST36490LT5K&itemtype=K


:cheers:
Tom

[scottfab]

I guess not ... unless that's the book that most people keep in the car with them. I have a 1990 Corvette book in the glovebox.

What other literature do you suggest that I pickup?

Here is a link to many sources for the FSM (field service manual)
http://www.zr1netregistry.com/Information/TechNet/DocumentsManuals/tabid/112/articleType/ArticleView/articleId/106/GM-Service-Manuals.aspx

Seems that my start time is not too much to worry about. Do ported engines usually take longer to fire up? It may be the LPE chip too I guess?

Could be the cold weather too , I will see how she responds this summer.

I appreciate it ---

Start time seems well within reason. Try the various methods suggested to shorten the time. Just don't let go of the key too early for reasons mentioned.

[alwayscode390]

Thanks for the links guys!!! ---

[Hib Halverson]

Typically, on a cold start, crank time will be longer. Looking at that footage, yours seems right on the "line" between ok and a little long. I say that in part, because of the fast crank speed---you must have a Odyssey battery or something like that---which should have the engine firing in a shorter time than most other ZR1s with a battery, cables and starter in the typical condition those parts on most cars would be.

I'd run the fuel pressure tests in the factory service manual just in case you've got a leaking injector.

[alwayscode390]

OK, I will definitely check the fuel pressure soon. I appreciate the advice Hib, thanks ---

[Hib Halverson]

Well, 6 seconds seems a bit on the long side. Mine is about 3-4 seconds AFTER the fuel rail is charged.
Ya know, when I posted above, I didn't really time that video, but Paul must have and I agree with him, if it's six seconds, that's a bit much. My 95's start time after fuel pump shut off, is about the same as Paul's

Before rolling the ignition switch over to START, turn the switch to the "ON" position and listen to the fuel pumps. When they stop running, the rail is up to pressure, but it takes maybe a couple seconds before the rail (on my 90) is up to pressure. If I roll to the START position before the rail is charged, I can see how that might invite a backfire (NOT GOOD) at the very least. But, also add a second or two to the normal 3-4 second (cold) start time.

Once it has been started and run that day, the start time is much quicker - sometimes under a second!
My 95 has always behaved the same way. Couple of points, though...when the pumps stop running, the fuel system may or may not be at the correct pressure. The pump-cut off is not related to fuel pressure. If you've got a pump out, leaking pumps, leaking regulator or leaking injectors, its possible the fuel pressure is not at a nominal level when the cut-off occurs. The cut-off is related to how long (2 sec.) the ECM will allow the pumps to run without an rpm signal, not fuel pressure. When you turn to "run" the ECM turns on the pumps but, if it doesn't see the engine running after two seconds, it turns off the pumps.

Also, if you've got the key in start, the engine is cranking but fuel pressure is not up, the engine will not backfire nor are you inviting it to do so.



And, if nobody told you, you want to hold the switch in the START position for almost another second after it fires to let the motor rpm start coming up. This avoids backfires which tend to blow hoses off the MAP and the Fuel Pressure Regulator (for starters) at the very least, or rupture diaphrams in said parts (rare, but happens). This trick might avoid a plenum pull to re-connect a vacuum hose. Just sayin...

P.

Holding the key in "start" after the engine is running is pointless and might not be the best thing for the starter. Intake manifold backfire won't happen once the engine is running.

The infamous backfire occurs if the start cycle is interrupted but the key remains in "run" rather than going to "off". If the engine attains some rotation but not enough run, the ignition is hot and the engine is at a certain position with the right intake valve open, sometimes air-fuel mix in the plenum will ignite. The resulting "bang" sometimes takes out the MAP sensor and/or blows vacuum hoses off the nipples at the front or the rear of the intake manifold.

[scottfab]

Ya know, when I posted above, I didn't really time that video, but Paul must have and I agree with him, if it's six seconds, that's a bit much.
...snip....

I'm measuring 4 sec on the video posted.

As for holding the key on a bit longer after detecting a start, the empirical
evidence is there from many owners. This eliminates the otherwise usual backfire from releasing early. I would say 1 sec to be an excessive estimate, more like 0.5 sec is all that is needed. Very repeatable.

[alwayscode390]

Just went back out, tried with priming the pumps ... and it took about 5 seconds. I don't think it made a change. I feel alright about it though at this point ---

[Paul Workman]

Ya know, when I posted above, I didn't really time that video, but Paul must have and I agree with him, if it's six seconds, that's a bit much. My 95's start time after fuel pump shut off, is about the same as Paul's
My 95 has always behaved the same way. Couple of points, though...when the pumps stop running, the fuel system may or may not be at the correct pressure. The pump-cut off is not related to fuel pressure. If you've got a pump out, leaking pumps, leaking regulator or leaking injectors, its possible the fuel pressure is not at a nominal level when the cut-off occurs. The cut-off is related to how long (2 sec.) the ECM will allow the pumps to run without an rpm signal, not fuel pressure. When you turn to "run" the ECM turns on the pumps but, if it doesn't see the engine runningk after two seconds, it turns off the pumps.

Also, if you've got the key in start, the engine is cranking but fuel pressure is not up, the engine will not backfire nor are you inviting it to do so.



Holding the key in "start" after the engine is running is pointless and might not be the best thing for the starter. Intake manifold backfire won't happen once the engine is running.

The infamous backfire occurs if the start cycle in interrupted but the key remains in "run" rather than going to "off". If the engine attains some rotation but not enough run, the ignition is hot and the engine is at a certain position with the right intake valve open, sometimes air-fuel mix in the plenum will ignite. The resulting "bang" sometimes takes out the MAP sensor and/or blows vacuum hoses off the nipples at the front or the rear of the intake manifold.

I'd heard about the backfires before it happened to me once. The problem, like you alluded (sp?) to occured in that split second where it sounded like it fired, but actually failed to fully catch. Maybe it did fire on a cylinder, but missed the next one or two. In any case, I released the key, and POP! Just that quick and troubles followed.

Lucky for me it was just the MAP hose (now secured with a small tie-wrap as insurance against that happening in the future) and no further damage. Now I hold the key - perhaps not for a full second - prolly less than that, but I make it a point to hold it in START until I'm absolutely sure it is really running (i.e., more than just a single cylinder or two that fired, is my intention).

I know the bendix on the AC/Delco starters on the gen I SBC/BBCs are designed to "free wheel" when the engine starts and the speed of the flywheel over-runs the speed of the starter. I'm pretty sure it is the same for the LT5 starters, but can't say for sure. But, in reality the length of time I hold the switch in the START position is "under a second" - more like half a second or maybe less before I'm satisfied the motor is really running (for good) and the key is released. So far so good, far as my starter goes, and NO backfires since, far as I know. However, once in a while I will hear a cylinder fire and not be followed by one or more cylinders following. I'm glad I was still holding the switch in START - smoothly passing over until the motor catches for good.

Not being in a big hurry to release the switch from the START position was foretold to me, and then taught first-hand by a few experiences since...YMMV. Just sayin.

P.

[alwayscode390]

Thanks Paul ... I love words of wisdom like that.

I will definitely be thinking of this every time I start my car from now on. :) ---

[Tyler Townsley]

OK, I will definitely check the fuel pressure soon. I appreciate the advice Hib, thanks ---

In the calibration there is an 'accel pump' shot of fuel when the motor turns over in the crank cycle. There is a 'map' that is selected by the ecm and this map selects a time of the injector shot based on temp and a multipler that can be changed. I had to change this figure to get the prototype to start. There may also be other time base controls that are derived using temperature. I remember a discussion somewhere that indicated there was a time delay of this 'fuel pump' shot to allow for oil pressure and it was delayed based on temperature among other things. As has been pointed out your troubleshooting starts with a fuel pressure guage to make sure the pressure is adequite then you watch the fuel pulse timing and volume.

Tyler

[alwayscode390]

http://i49.tinypic.com/291kgli.jpg

I just got back from installing a new Odyssey battery.

Not sure if it was the warm weather (70) ... or because I REALLY needed a battery ... but the car seems to love it. Starts after 1-2 seconds now , instead of 5-6 !!!



YAY!!! ---

[Hib Halverson]

Maybe it was a weak battery causing the long start time, all along.

[Blue Flame Restorations]

The "weak battery" hypothesis got me to wondering. The Purple 95 takes considerably longer to start than my Turq car. The Turq car has an Optima battery purchased last year.

I just checked the battery in the 95 and it's the original. Having only 9k, I suspect that it's most likely been on a battery tender most of its life.

[alwayscode390]

I'm wondering how sensitive these cars are to old batteries. I know the vipers are known to being sensitive. ---

[Paul Workman]

The "weak battery" hypothesis got me to wondering. The Purple 95 takes considerably longer to start than my Turq car. The Turq car has an Optima battery purchased last year.

I just checked the battery in the 95 and it's the original. Having only 9k, I suspect that it's most likely been on a battery tender most of its life.

Things that make you go Hmmmm....!

Just thinking out loud (uh, oh...) I suppose because I've not had a hard starting problem (knock on wood), that I assumed the starter itself wouldn't engage if the voltage durring crankin dropped below a certain threashold (compared to an AC/Delco vis a vis a SBC) - and maybe that IS also true as well.

But, now my curiosity is piqued: there may be other things e.g., fuel, spark, that could be affected even IF the starter is rolling the engine over. It would be interesting to know what that threashold voltage is, if that is the case.

Hmmmmm.....

P.

[Blue Flame Restorations]

Paul, I don't know if my injectors are the originals. I'd bet .50 cents that they are. The starter may just turn a little slower??????

Anyway, it starts. Just cranks a little longer than my Turq car that has the Optima.

If I end up putting an Optima in the car, I guess I'll find out if it changes.