Replaced battery, now will not run

[FormulaReed]

About 2 weeks ago, I replaced the TPS, plugged in my scanner and set the TPS voltage. Car was running good. Went for a drive, turned her off and on and everything was fine.

The forecast was calling for some snow and I knew that I would not be driving the corvette for awhile so I took the battery out and plugged it into a float charger.....

Well, today the weather was great and I wanted to take the vette for a spin, nut when I put the battery back in it cranked fine, started up but than died. I tried a few more times and got the same thing. I can smell fuel, so I think it's getting fuel.

Any ideas? It wants to run, but it turns off like the ignition is being cut.

My car is a 1991.

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[RussMcB]

Sorry no one smarter than me has responded yet. :-)

That rings a bell, like maybe one fuel pump cuts off after starting?

Maybe the FSM has a troubleshooting guide to help identify the problem.

Good luck. I'm sure someone will be along shortly who can offer a better answer.

[Paul Workman]

About 2 weeks ago, I replaced the TPS, plugged in my scanner and set the TPS voltage. Car was running good. Went for a drive, turned her off and on and everything was fine.

The forecast was calling for some snow and I knew that I would not be driving the corvette for awhile so I took the battery out and plugged it into a float charger.....

Well, today the weather was great and I wanted to take the vette for a spin, nut when I put the battery back in it cranked fine, started up but than died. I tried a few more times and got the same thing. I can smell fuel, so I think it's getting fuel.

Any ideas? It wants to run, but it turns off like the ignition is being cut.

My car is a 1991.

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What does the scanner tell you?

Start with the scanner and verify too, FUEL AIR SPARK and get back to us!;)

[viper107]

could just be that the idle air motor has to relearn itself from the battery being out of the car(unhooked)

[ZWILD1]

I don't think the battery being out should have affected it. I have had a battery that not used more than every 2 weeks needed to be charged. I charged the battery again and then left both terminals off for just over a month. This past Monday I went to our local Chevrolet dealer and bought a new Delco battery. Hooked it up and the car started right up no issues.

[FormulaReed]

I got some time today to work on my z, and here's what happened.

I hooked up my scanner tools and tried to start the car. It did exactly the same thing, it would crank over, fire and die.

No codes were showing, the first picture is what the scanner was reading. The iac position was reading 150 steps and the desired idle speed is 3187.5 rpm. I tried to start it a few times but it started to smell like un-burned fuel and I did not want to back fire the car and damage something.

I went back in my house to check if the iac position was right. I went back to my car about 10min later and tried again.

This time it started but was misfiring bad, but kept running. I snapped the 2nd photo when that was happening. No check engine light.

It settled down and idled fine. Sounded good. I reved it a few times and it responded like it should. Sounded good and was acting like it wanted to go for a drive. I snapped the 3rd photo during that.

What do you all think? Is my iac sticking and causing it to not start? It never threw a check engine light the whole time. Should I replace the iac?

Thanks in advance.112481124911250

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[Ccmano]

So the first one was with the engine not running and the two other were with the engine running? Notice the battery voltage on the first one. 11.4 volts. The voltage is higher on the second two because the alternator is charging while running. That battery is either bad or seriously discharged. Low voltage batteries can cause a these weird things. Step one is get a volt meter and get a reading on the battery without the engine running (static) if it’s anything less than 12.4 volts the battery either needs a serious charge or it’s bad. A float charger won’t do. Once you have a good battery in place try starting the car again see what happens.
H
:cheers:

[FormulaReed]

Correct, the first one is when it would not start. The battery is under a year old and was charged the first time this happened. I think it was low from trying to start it last week, not chargeing it this week, and i had given it a few tries before I did the screen shot.

After I posted it went for a drive and all semed well. Turned it off and on a few times, and it acted ok.

I want to figure out why it was not starting though.

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[Ccmano]

Correct, the first one is when it would not start. The battery is under a year old and was charged the first time this happened. I think it was low from trying to start it last week, not chargeing it this week, and i had given it a few tries before I did the screen shot.

After I posted it went for a drive and all semed well. Turned it off and on a few times, and it acted ok.

I want to figure out why it was not starting though.

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Just because the battery in it is under a year old doesn’t mean its good. Now that you’ve driven it the alternator has charged it some and brought back some of the charge. It may keep starting for a while until the battery is discharged again. The battery is the first thing that has to be eliminated in determining a starting issue. Based on those voltages your battery is still suspect. Take it to an Autozone store or where you bought it and have a capacity test done. If it’s good get a solid charge on it. Then if the issue continues you can keep looking. Granted there are several known issues that can cause this but without eliminating the battery first you may be spending a lot of time, money and frustration for nothing. It’s a step by step process, the battery is step one.
H
:cheers:

[FormulaReed]

Got it. I will take the battery to the place I got it from and see what they say.

Thanks

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[Dynomite]

About 2 weeks ago, I replaced the TPS, plugged in my scanner and set the TPS voltage. Car was running good. Went for a drive, turned her off and on and everything was fine.

The forecast was calling for some snow and I knew that I would not be driving the corvette for awhile so I took the battery out and plugged it into a float charger.....

Well, today the weather was great and I wanted to take the vette for a spin, nut when I put the battery back in it cranked fine, started up but than died. I tried a few more times and got the same thing. I can smell fuel, so I think it's getting fuel.

Any ideas? It wants to run, but it turns off like the ignition is being cut.

My car is a 1991.

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If you smell gas then could be Fuel Pressure Regulator........especially if the LT5 starts after sitting for a while then floods out and quits.

Starts up then begins to run rough and dies (http://www.zr1.net/forum/showpost.php?p=304297&postcount=12)

[FormulaReed]

I'm hoping to get sometime this week to work on my car.

Will a bad fuel pressure regulator show with just a fuel pressure gauge on the fuel rail? Can I inspect it with out pulling the plentium?

I

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[Dynomite]

I'm hoping to get sometime this week to work on my car.

Will a bad fuel pressure regulator show with just a fuel pressure gauge on the fuel rail? Possibly depending on how big a leak....but if you have raw gas (or smell gas) within the Plenum that is a sign of leakage.

Can I inspect it with out pulling the plenum? No....Unless you have Phil's Modified FPR :thumbsup:

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The "Valves" within the FPR can corrode or collect rust particles.
https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x400-1/80-img_2639_b258d789e83c5fd652fe7cbb621e10acee060b4a. jpghttps://cimg9.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x400-1/80-img_2641_95be2ec9fc1a3e45a4e00dc7abcd3e04938ff986. jpg

Phil's Modified FPR (Before and After Installation.
https://cimg6.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x400-1/80-img_2632_18cedbc38107145546d4bdd7d9e774915a2b5bd9. jpghttps://cimg2.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x400-1/80-f20_6e398eb8d56edc2c87516d558819f1ed552e4baa.jpg

[FormulaReed]

After some down time due to an attempted theft and having to get the steering column rebuilt, I'm back to trying to fix my car....

I put the column back in, took the battery off the charger, hooked it up and tried to start her... I was pretty shocked when she fired right up and settled into a nice idle. So I let her warm up, and all was good.

I went for a drive today, and it was running great, just mobbing on the freeway, doing 70 in 5th. I went to give it some gas and she just fell on her face.

I pulled off the freeway and the idle was hung at like 1.5k. It never died, but it was not happy. Felt like it was misfiring, but cleared up once the revs were up. Never got a cel.

So. I got home and hooked up my scanner. No codes. The only thing I saw was that the TPS voltage was a little high (.61v) so I set it to .55v. Restarted the car and it ran like ****. Turned it off, turned it back on and it ran fine. It tossed a code 42.

I decided to pull the plugs. They looked fine, but I replaced the, anyway. The only thing was that one was really loose, like finger tight at best. After I did that, I started the car and it ran pretty good. I went for a drive and did some data logging. It ran good, but the idle was still hanging. Didn't drive in on the freeway.

I've replaced the TPS sensor, crank position sensor, map hose, both fuel pumps.

It seems ok when it's cold, but once it's warmed up the issues start. Could a loose spark plug cause this? Would a bad o2 sensor cause this, I'd think it would throw a code? IAC? What should it read at idle and how much should it change when I'm driving?

Thanks in advance.



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[BigJohn]

Did someone foul your gas?

[lfalzarano]

I’ve lost several plugs that came loose and popped out. A loose plug gives you a rough idle only in my experience. A blown plug makes a horrible sound!

The high idle might be the IAC. After fixing that, it still ran high. Finally, sent the throttle body to Marc. He found a piece of gunk on the engine side of the throttle plate, causing the high idle. Plus , installed Marc’s chip which also helps.




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[Ccmano]

I’m confused, you covered a lot of territory here. You mention several issues but not if they were fixed. Is the high idle the only issue that remains or are there others?
H
:cheers:

[FormulaReed]

I’m confused, you covered a lot of territory here. You mention several issues but not if they were fixed. Is the high idle the only issue that remains or are there others?
H
:cheers:Haha. Yeah, that post was not super clear.

The idle is still hanging when it's warmed up. It's worse if it's been driving at a constant speed. If im shifting through the gears it's ok.

I didn't drive it very far after I replaced the plugs, so I'm not sure if that cured the throttle issue.

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[FormulaReed]

Update: I replaced the IAC today. The old one looked pretty bad and there was a bunch of carbon crud on it and in the housing. I cleaned up the passage way and installed the new one.

I let it warm up and went for a little drive. It seems like the throttle hanging and high idle are fixed. Might just be psychological, but the throttle response felt really good.

It still doesn?t come down to idle right away, it takes a few seconds for it to come down. But I?ve heard that?s somewhat normal.

It feels like the idle is low, it?s 675 rpm when warm. Is that ok? What are others seeing?

Thanks!

[Paul Workman]

If you said what year yours is, I missed it. But, mine is a 90 and after highway speed/rpm and comming to a stop, the idle is high initially before dropping gradually to normal over 2-3 seconds.
Also, if for any reason the engine should stall while the car is rolling (happens occasionally on hot humid days with the clutch depressed), the car has to be brought to a complete stop for 2-3 seconds before the idle will return to normal. And, the same thing after shutting the hot motor off to fill the tank; high idle for 2-3 seconds. I've come to accept the behavior as "normal" for a 90, far as I can tell
However, my wife's 91 Z does not behave the same way. It never has done the high idle thing - @ least not yet when I've been behind the wheel.