What would cause my engine to die upon startup?

[porsche911girl]

Hey all,

I haven't fallen off the face of the earth, in case any of you were wondering, I've just been extremely busy with school and working on my Jeep, so I've been frequenting the Jeep forums a lot recently.

Anyway, last Sunday my dad and I went up to the lake to check on the place and the cars, and something weird happened when I went to start the 911. The engine turned over fine, but then died very quickly thereafter. In other words, I couldn't keep the engine running after the initial spark I guess. I have only ever had this happen before on my Jeep, and the only way we could keep it running was by keeping our foot on the gas pedal (this was when it was at the body shop being repaired from a wreck...the same body shop that had called to say it was ready only for us to go out there to pick it up and then them telling us it wasn't finished yet...but I digress.)

So I tried it again a few times, after waiting a few mins between each time, and each time it'd do the same thing. It was in neutral with the e-brake up and I was holding the clutch in when I turned the key.

I tried to give it a little gas when I started it to see if that would keep it going, but it didn't seem to help.

I was afraid to go any further with it so my dad stepped in and tried to start it and it did the same thing. However, he was able to keep it going but then it backfired. Afterwards, it sounded like something was hitting something else in the motor, which concerned me, as I know how much motors can cost to be repaired.

He eventually was able to keep it running and the idle returned to a normal sound, but when we took it out for a drive, it rode really rough and was a little hard to shift into all 5 gears. In fact, it rode pretty rough thru all the gears, not just the 1st and 2nd, as it's done before when we took it out a few weeks ago (New Year's Day).

So we only really drove it maybe 15 mins or so, and put it back as my dad didn't want to worry about getting stranded on the road somewhere.

It was about 29 or 30 degrees when we took it out, so it could've just been it was reacting to the really cold weather, I don't know...it is a 30 yr old car. My neighbor who had it before us said that it was really only a spring-fall car, he rarely drove it in the summer or winter, but I feel you should be able to drive a 911 whenever you want to; there's plenty of people who use them as daily drivers.

I don't know if this has any effect on the startup issues, but the last 2 times we've been at the lake (several weeks between them), the battery seems to be very low or dead, but my dad was able to get it started the first time by giving it some gas, and the 2nd time he quick-charged the battery and we took it out for about 30 mins or so (maybe longer), but then we didn't go back up there for over a month later.

Bottom line, my dad doesn't know how to properly care for a car, much less a vintage sports car. And I don't know enough yet to be confident in taking care of it myself.

But does anyone know what may have caused this? I'm pretty sure it has the airbox pop off valve and carrera chain tensioners upgrade, but I'm a little worried we might have blown an air box.

[Superman]

Never, ever jump to the most expensive and complex fault mode assumption. Everybody does that, and it's usually not a correct assumption. For example, somebody hears a squealing noise when they're driving down the road. Obviously, a failed transmission that needs rebuilding, right? Nope. Loose fan belt.

Your balky transmission is a 915. Get used to it. Replace the shift bushings, adjust properly, install Swepco lube, and drive.

Air box is probably fine. Probably. Sounds like it needs to be driven more, and it may need a tuneup. New battery, fresh plugs and cap and rotor. Fuel mixture setting. Should run fine.

[porsche911girl]

Originally Posted by Superman

Never, ever jump to the most expensive and complex fault mode assumption. Everybody does that, and it's usually not a correct assumption. For example, somebody hears a squealing noise when they're driving down the road. Obviously, a failed transmission that needs rebuilding, right? Nope. Loose fan belt.

Your balky transmission is a 915. Get used to it. Replace the shift bushings, adjust properly, install Swepco lube, and drive.

Air box is probably fine. Probably. Sounds like it needs to be driven more, and it may need a tuneup. New battery, fresh plugs and cap and rotor. Fuel mixture setting. Should run fine.

Thanks Supe! Sorry to hear about your accident. If you were closer, I'd let you drive the 911 as you're correct, it does need to be driven more and for longer than 30-45 minutes probably too.

[DRACO A5OG]

Hi P911girl,

How old is the fuel?

Have you tested the Battery's Charge?

[Rot 911]

Old gas that probably has water in it.

[DRACO A5OG]

Originally Posted by Kurt V

Old gas that probably has water in it.

Hey quit reading my mind, it's spooky or at least unstable fuel. She may need a fuel stabilizer or new gas

[old man neri]

2 side notes. Firstly, I have started my 911 ('88) in much colder temperatures than 30 degrees. I wouldn't worry about that, unless you are running a really thick oil. Secondly, I would be careful about storing your car with the e-brake on. It might cease over time.

Good luck!

[porsche911girl]

Well here's the latest on it.

This afternoon when I went to start it, it would only make a clicking noise, yet all the interior and exterior lights worked, so I figured the battery wasn't shot completely. So we charged the battery for about an hr and tried again, only this time it'd do the same thing, turn over then die, it did this once and then it backfired on the 2nd attempt. So we didn't mess with it anymore.

I will admit that it hasn't been driven for a few weeks so that probably hasn't helped anything, but the way it drove last time doesn't exactly make me wanna jump in for a spin...

Anywho, I don't know if it's a battery issue, WUR or alternator, or starter solenoid, and we had to leave before we could do anything further on it.

But either way, this really stinks!!!

Edited to add: as for fuel, I have no idea how old it is but as it spends most of its time sitting in our garage, I imagine it's fairly old. It's been so long since we last filled it up, it could easily have been early last year (as bad as that sounds).

What would cause it to backfire tho? Any why is it that if I take my foot off the gas pedal, it immediately dies? That's very disconcerting!!

My neighbor at the lake is going to get it inspected and I'm going to ask him to take it to whoever he took it to up at the lake when he owned it and see if they can diagnose the problem...of course, I'm sure a good tune-up couldn't help... I'm about to get one done on my Jeep b/c it's not been right either...guess that's what I get for lifting it!

[WPOZZZ]

How old is your battery? If it is old, you should replace it. If not, test it and charge it up. Do you have ethanol in your gas? If so, put some fuel stabilizer in the tank as that may help, but you really need fresh gas.

[slodave]

It's angry at you! Bad Porsche owners! Your car is quietly screaming "Drive me! Drive me!".

[porsche911girl]

Originally Posted by slodave

It's angry at you! Bad Porsche owners! Your car is quietly screaming "Drive me! Drive me!".

Haha that's probably true. I'm the only person in my family who firmly believes that cars have souls and different personalities, at least the ones I drive...well the 911 can wait in line b/c right now my Jeep is mad at me for lifting it and getting bigger tires...

However, if it wasn't for me, the car would get driven even less than it does

[72 four door]

Ok next time your there pull the air filter out and check that the box didnt break. Do you have a pop off valve? If it did theres 1 problem solved,cause she will run poorly with a bad box. Bring a battery tester with you [ohm meter] and check battery. Bring spare battery also,or a battery charger. And also llike other have said bring a fuel stabilizer with you. Good luck with her,she probably is pissed at you.[or in your case he!]

[CharlesJones]

Hi P911Girl,

As others have said it probably is just that it needs a tune-up, and maybe the battery is shot too. I didn't run my car for about 8 months or so once, so I charged the battery up but when I came to start it all I got was a loud repeated clicking noise because the battery was shot (I think the clicking is the solenoid clicking away, although the battery's not capable of spinning the engine). So I bought a new battery and then the car started, back fired and ran like crap before dying again. I couldn't get it to do anymore than that, so I changed the spark plugs, ignition leads, coil lead, distributor cap and rotor, and the coil for good measure, and it started and ran like a top! And it's been great ever since!

If driven reasonably regularly these cars should start no problem, and should prove very reliable. Honestly, my car now starts instantly whatever the weather, and has been more reliable than my modern daily driver (although I don't do so many miles in the porsche, I have to admit). If you have an interest in the mechanical side of things I suggest you just get in there and change the battery and all the ignition bits yourself - it can't do any harm - and then drive and enjoy the car! If you use it more regularly and also maintain it yourself, I think you will find like I did that they are very trouble-free cars.

[Turbo Den]

i am facing a similar problem now.
car stored away for few months.
it starts, but idle rev slowly lower and lower and die in 3 minutes, everytime.
so, any suggestions to you, i will try too and let you know how it goes.
Good luck on your's too.

[gregg911]

I had this problem on my SC when I bought it. Inside the top of the airbox, there is a thing that looks like a round flat plate, check to see that when the car is turned on but not started that your fuel system is creating pressure to push this into place. With the car "on" but not started and the airbox cover off, the fuel system will pressurize (you'll hear it) and this plate will have some resistance when you push on it lightly. I had almost no pressure, checked the fuel system pressure, it was low, replaced the fuel pump, accumulator and filter and it ran great.

I also recently had a backfire on a cold morning and the car would start and run for a second and die. If you've had a backfire then the popoff valve may have some leakage around the area where the epoxy meets the box, check that, if it looks bad, re-seal it.

[sjf911]

If the fuel pump relay (FPR) is bad or the CIS sensor plate circuit is shorted, it will turn over while cranking but die after the key is released.

[porsche911girl]

Update: Still having the same issue, but my dad has finally brought it back to Charlotte to take it somewhere to have a full tune up (which it no doubt needs). However, now it backfires once when he's trying to start it, and it makes a loud popping noise when he is finally able to keep it started and the sound continues as he drives it. He says it doesn't want to shift into 2nd gear very well, and yesterday I had to help push the car down the driveway as my dad couldn't get it to go in reverse.

Does anyone know a good place in Charlotte to take it? I was thinking either the 911 Shop or Eurowerks. I know it needs the gas and oil lines flushed and changed, at the very least, but I worry that if my dad keeps driving it as it is, that he will blow the engine or something bad will happen and then he'll balk at the money it would take to fix it.

Just me and my worried mind again, I guess...

So does anyone know what the popping sound would be? It also idles very badly once he gets it started. He must've tried about 10+ times this afternoon to get it to stay started. It has a new battery, so I don't think that's the issue.

Any help would be greatly appreciated! I will post a video soon where you can hear the sound it's making.

[porsche911girl]

It's not a great vid, but it is what it is:



PS You'll probably need to turn the sound up on yer computers cos for some reason it's not very loud.

[Porsche_monkey]

Popping and backfiring like that makes me think it running too lean. I don't know of anyone in your area, but somebody here will.

Sounds like a Porsche Pro should tend to it now.

One tank of gas in a year????

[ramonesfreak]

how was it brought home? if it was driven, how many miles? if it was driven quite a while to get it home and it is still like this, then i would take it in to a shop.

if it was towed, i would first fill it up with fresh gas, a bottle of fuel injector cleaner and go out on the highway and get it some exercise. mine was like yours when i first bought it because the owner had it sitting for about 1 year. kept stalling and was running very rough..... it straightened itself out after a nice long drive with some high revving, fesh gas and fuel injector cleaner. if that dont work, take it to a shop for a diagnosis. good luck. seems like a minor adjustment, bad spark plug wire(s), mixture off, airbox crack, bad gas etc...