Help for the new lady? My bad boy stalls!

[s2sue66]

Hello all, new to the board and a fairly new Porsche owner. Read lots of past posts and a ton of great info but nothing seems to fit my problem.
Have '87 911 Carrera and love it to pieces. I will drive it out for dinner ( live for the looks it gets) then after it has sat for about an hour or so I try to leave. It will start and go a few blocks but then stalls out.
Nothing will get it started again. If I leave it sit for a few hours it will go like nothing ever was wrong.
Changed out the fuel filter but still have the problem. The fuel pump would be my next target, but it only does it after I have taken it somewhere and then turned it off. So not all the time as what the pump would lead me to believe.

Any advice would sure be appreciate. I am trying to learn all to keep him going, but he is nothing like the mustangs I am used to.

If there are any Iowa Porsche people, drop me a line. I need to start making contacts.

[dentist90]

The Motronic cars are not prone to vapour lock... besides if that were the case it wouldn't want to start after sitting hot.
When it stalls out does the starter still crank OK? Sounds as if there is a heat-related problem, but I'm stumped.

Time to call JW!

[Nashville84Cab]

Have you tried replacing the DME relay under the driver seat? The DME relay is also the fuel pump relay. They are cheap and you should always have a spare in your glove box as it is only a matter of time when you will need to replace it. BTW order a couple from our host. Good luck and keep us posted on your progress.

[brownbutter]

My 74 had a similar problem, it would start and drive perfectly, and I'd park it for a couple of hours and then it wouldnt start, or when the motor got hot it would run poorly and run really rich then die out...
at first it we thought it was leaky injectors making the motor run rich and then end up fouling the plugs. it made sense (at the time) the reason it would start like nothing was wrong after sitting for a couple of hours was because the plugs would dry up...
replaced the injectors an the seals
but that wasn't it
we then replaced the coil...
that wasn't it either
replaced was the ignition box and ajusted the fuel air mixture and i havent had the problem anymore...the Ignition box was was acting up after the motor got hot and making the motor run rich.

[ToddM]

+1 Nashville84Cab

DME relay, my 964 Turbo did the exact same BS as u described.

[Milu]

DME relay first. It's a good idea to keep a spare on a 3.2 anyway.
if that doesn't sort it check the cht sensor, followed by the other sensors. It may be worth checking out the service history to see if they've been replaced recently. They're not expensive items and don't last forever.

[Isabo]

Can't help with the tech question, but welcome to another lady Porsche owner.

[Thomas Owen]

Have you driven it long enough to see if it will stall while driving, or are you sure this is just a starting problem after it has been shut off?
Try the DME relay first, then maybe the cylinder head temperature sensor.
Good luck-

[JeremyD]

DME Relay first - When's the last time you changed the distributor cap and rotor?

[88911coupe]

It sounds like from your description it is turning over but not starting...correct? Definitley replace the DME relay but it may also be an intermittant connection in the DME unit itself. I had some starting problems in my '87 cab that weren't fixed with a new DME relay. It was a broken solder that got worse when the car was warmed up...I guess it expanded or something. There are threads on how to repair it but it is really hard to see, in particular if you have over 40 eyes like I do.

[defcon65]

I'd start with the DME and fuel pump relay - buy them from our host (inexpensive) and install them - very easy, like plugging in a night lite.
They seem to be likely suspects for what you are experiencing.

Welcome to the forum! I'm in Davenport and there are maybe three or four other Iowa Pelicans that I know of.

And we're gonna need a photo of your car, BTW. It's de rigeur.

Regards,

[Wil Ferch]

For clarity...the "DME relay" is ..of itself...a dual-relay, one side of which is the fuel pump relay...

I believe this is different than the 78-83 CIS injection cars...which have a singular "fuel pump relay"...

- Wil

[detroiter]

[QUOTE]Originally posted by 88911coupe
I had some starting problems in my '87 cab that weren't fixed with a new DME relay. It was a broken solder that got worse when the car was warmed up...I guess it expanded or something.

I had the same problem with my 87 cab. I had to slide back the driver's seat, jiggle the connection of the harness and the DME box to get it started a couple of times. We cleaned up the connectors but eventually I came across a rebuilt DME unit.

I believe that over time, moisture will cause poor connections (especially in cabs?)

Good luck!

[DonMo]

I just fixed my 84 3.2 with the exact same symptoms. The Motronic has a large darlington transistor on the heat sink that has 1012 written on it that gets tired when it is old an won't start when hot. I ended up diagnosing it myself and replacing it myself for $10 bucks counting shipping. Now that is the short cut, now let me tell you the stuff I changed that didn't need changing trying to fix the problem. Cylinder head temperature sensor, dme, rotor, cap, plugs, fuel filter, to name the easy stuff.

PM me and I wil give you the transistor part number and what to do. If you have any electric skills or a friend with electric skills it is easy.

[ToddM]

Could be worse, we could be on a Lotus forum

[s2sue66]

Thanks TONS to everyone! Long live the internet for such valuable resources. I have ordered the DME and fuel pump relay switch (from the sponsor of course!)and will start there. If that is not the fix, then will move on to more of the involved areas to look at. The darlington transistor on the heat sink sounds interesting. :-)
I have the book 101 projects for your Porsche 911, and am considering the service manual by Bently. Has anyone found this to be helpful or not really? I hate to spend $90 on a book of no use.

I will get a pix posted this weekend. I knew that was standard from the other posts. He is a bit dusty so need to wash him before the pose.
Thanks again for all the great advice, I had no idea where to start on this trick.

[88911coupe]

The Bentley manual in incredible. It's extremely useful even if you aren't doing the work just for the detailed information it provides. I also have both of Wayne's books and they are in a class by themselves for accuracy and graphics. Too bad others don't have his attention to quality.

[dentist90]

Originally posted by s2sue66
...I have the book 101 projects for your Porsche 911, and am considering the service manual by Bently. Has anyone found this to be helpful or not really? I hate to spend $90 on a book of no use.

Not helpful... Essential! Must have. The only thing better would be a Porsche factory shop manual, but these are very pricey. My Bentley is dog-eared and filthy now, just the way it should be!

A free parts guide (PET) on PDF is available from Porsche. It can be very helpful for identifying parts #'s of things you may need, plus exploded diagrams of the car. Maybe someone can post the link for this.

[dentist90]

PET Link for PDF copy of parts list.

[s2sue66]

Thanks to all who have helped me. I replaced the DME switch under the drivers seat, oh, what a twist that was to get at.
Things are going well now, and have not had the stalling like before but not sure I am creating the same conditions as when it stalled~ hesitant to get myself stranded by the road again.


Ordered the
911-615-108-01-M58 Fuel Pump Relay, red, 911 (1975-89)
which I thought was seperate or in addition to the DME switch, but it seems that my car does not use this? Am I missing something here? Is this only in the Turbos which mine is not? Nothing under the seat that looks like this and the shop manual only indicates to the DME switch being there.

Got my copy of the Service manual and it has already been helpful enough to pay for it's self.