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1986 Porsche 928s turns but will not start

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1986 Porsche 928s turns but will not start

 
Old 03-21-2017, 08:08 PM
  #16  
MahoreLee
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Originally Posted by Leon Speed View Post
Press the gas pedal down all the way while you start the car.
It started! And now it starts without the gas fully depressed but still starts rough.

What does this mean?
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Old 03-21-2017, 11:01 PM
  #17  
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probably a fuel damper or fuel pressure regulator has failed pull off the vacuum line and smell it for fuel if you smell fuel then its best to replace all 3 of these parts
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Old 03-22-2017, 06:09 PM
  #18  
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Originally Posted by MahoreLee View Post
It started! And now it starts without the gas fully depressed but still starts rough.

What does this mean?
As I understand it depressing the gas pedal fully while cranking cuts off the fuel injection and opens the air flow. So when the engine is flooded it helps to get things "dry". YMMV. This is just a helpful way to start a flooded engine but says nothing about why the car starts rough in normal conditions.
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Old 03-23-2017, 12:00 PM
  #19  
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If it wasn't running ruff before the dead battery, then you flooded the engine by trying to start it with a weak battery.
Now the plugs need to be cleaned, so drive the car (not just around the block), starting and stopping a cold engine will foul the plugs as all get more fuel when cold and all get fuel even if its not their turn to fire, it's called "batch injection" google it

These cars need a fully charged battery to run correctly due to all the electrical drains and the ECU's.
Most won't go more than a few weeks w/o a charger keeping them up, so if you do not have a charger then disco the battery when not using the car by removing the ground strap under the tool tray.
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Old 03-23-2017, 12:27 PM
  #20  
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Thanks for all the help. The car is running and starting much better now.

I'm glad I removed and checked the gap for the spark plugs. They were mostly at .035 and one was at .020, so i adjusted them all to the proper gap.

I'll try checking the vacuum as sometimes you have to press the gas peddle a little after it starts or it will die.

But first to find the drainage. It's drawing 160 milli amp (I think that's the right unit). Now to pull fuses and try and get it down to 20.

Thanks again everyone.
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Old 03-23-2017, 01:55 PM
  #21  
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Good that you've adjusted it but spark plug gap is not the problem.

Check if the idle air controller is not stuck open.
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Old 03-23-2017, 08:57 PM
  #22  
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Originally Posted by MahoreLee View Post

But first to find the drainage. It's drawing 160 milli amp (I think that's the right unit). Now to pull fuses and try and get it down to 20.

Thanks again everyone.
That's a fairly big current draw and is probably what killed your battery...repeated discharging. Keep your new batt ground strap disconnected till you figure this out. My bet is on the rear defroster relay, that's the reason mine was discharging.

Cheers,
Brian
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Old 03-23-2017, 10:03 PM
  #23  
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Originally Posted by Brian'sIris View Post
That's a fairly big current draw and is probably what killed your battery...repeated discharging. Keep your new batt ground strap disconnected till you figure this out. My bet is on the rear defroster relay, that's the reason mine was discharging.

Cheers,
Brian
I actually just went through most of the fuses. Cig lighter (which does not work) took about 30. The interior light fuse took the majority of it. With it disconnected it draws just 8. I would leave it out but the after market radio won't turn on without the interior light fuse.

I'll search the forums for what to check now that I've narrowed it down to interior light fuse.
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Old 03-24-2017, 12:11 AM
  #24  
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Do the interior lights turn on and off when you open & close the door(s)?

There are little red lights in the backs of the doors that are hidden when the doors are closed. You can roll the window down and look into the inside of the door to see if they are on. It's also possible that a wire is shorting out and leaving them on all the time.
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Old 12-20-2018, 08:10 PM
  #25  
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Default 1986 928s

Hi , I’m new on this , I have 928s year 1986 it’s cranking but not start I have did the following:
new battery
new fuel pump
new fuel filter
new spark plug
I remove the gas tank clean it and clean the whole fuel system line
i removed the intake manifold and clean it
new valve cover
clean the throttle body
All the relay working
still not run
note: the car was sitting for years
any idea what should looking for
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Old 12-20-2018, 08:17 PM
  #26  
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I'd start with basic diagnostics.

Do you have spark?
Do you have injector pulse?

I would also suggest starting a new thread.

"Hello, I'm new and this is my car" threads are usually welcome.
Post some pics of the car, no matter how it looks.
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Old 12-23-2018, 01:24 PM
  #27  
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Originally Posted by rafed Salkini View Post
Hi , I’m new on this , I have 928s year 1986 it’s cranking but not start I have did the following:
new battery
new fuel pump
new fuel filter
new spark plug
I remove the gas tank clean it and clean the whole fuel system line
i removed the intake manifold and clean it
new valve cover
clean the throttle body
All the relay working
still not run
note: the car was sitting for years
any idea what should looking for
I suggest you start your own thread. Although your symptoms are similar, your parts are not the same.

Also new guys, please read the New Visitor thread. There is a diagram of ground points and a lot of other basic info there.

Most of us use batt maintainer, mine is a Schumacher. Batt drains can be impossible to completely solve, not impossible, but . . . .

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Old 12-23-2018, 06:33 PM
  #28  
rafed Salkini
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Originally Posted by SteveG View Post
I suggest you start your own thread. Although your symptoms are similar, your parts are not the same.

Also new guys, please read the New Visitor thread. There is a diagram of ground points and a lot of other basic info there.

Most of us use batt maintainer, mine is a Schumacher. Batt drains can be impossible to completely solve, not impossible, but . . . .
thanks for reply I’m gonna check the ground and see what’s gonna happens
and do you think may be the crankshaft position sensor
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