Newbie with 1977 911 2.7... and a first problem!

[mdrohrer]

Hi everyone,
my dad and I are very much into vintage 911's, and just 3 weeks ago I found him a close to perfect car to a reasonable price:
It's a 1977 Porsche 911, silver with an awesome red interior (pics to come...), of course the original 2.7 engine, about 95'000 miles on the clock. It is probably the best kept G-model in Switzerland for sale at this time. However, my dad brought it home, enjoyed for one short trip, and when we started it early this week, there was a loud sound like the engine had misfired, and it went dead. From then on, the engine starts and goes dead just a few seconds later again.
I did some research, already checked the fuel pump relay which is working and the fuses which are ok as well.
What comes to your mind reading this? Does that sound familiar to you? I'd be glad for any hints.
Thanks and Merry Christmas!

Marius Rohrer

[Grady Clay]

Marius,

Welcome to the Forum. Yes, pix are necessary for admission to the addiction.

I will guess “exploding air box.”

Remove the air filter and inspect the black plastic box for damage.
Have someone try and start the car while you hold down the air filter to the engine. The engine will start on the cold start circuit but with a cracked air box the air bypasses the CIS sensor plate and you don’t get any more fuel.

If this is the problem, the fix is a new air box and a “pop-off” valve to prevent future difficulties.

Best,
Grady

[PCA7GGR]

It might be that the rubber U-shaped boot on top of the injection system is blown off (easy fix), an unseated pop-off valve (easy) or a blown air box. (not easy) These are common issue with CIS 2.7s and 3.0s. The more problematic blown air box problem was addressed by an after market pop-off valve that is installed in the air box.

Start of checking the rubber boots that are held on by large hose clamps at each end. If that is OK, then pull off the air filter cover by unhooking the two rubber straps. Once the cover is off, you will hopefully see an aftermarket pop-off valve on the base. If it is there, make sure that it is properly seated and then try to start it.

There are other things that could be the cause of your starting problem, but these are some to start with. Good luck and Merry XMas.

[al lkosmal]

Hopefully you have a popoff valve installed in your airbox. To check, remove the airbox cover and airfilter. If you are lucky there will be a spring loaded valve that looks like a small toilet seat, for lack of a better description. These are bonded in and can come loose. If loose, you need to re-bond. If there is no popoff valve., I'd start checking the box itself for cracks.

[mdrohrer]

Hi Grady, PCA7GGA and al,

thanks a lot for your quick response, I realised this forum is going to save me and my dad a lot of time, money and nerves ;-)
After a quick glance at the airbox, it turned out that it has actually burst. Which is kind of wierd, if you think that a misfiring is something that could happen more than once in 28 years, why do you need to upgrade to an aftermarket pop-off-valve? Didn't they come up with a solution right away? Anyway, it burst right in the gasket line, like split in two parts. And one screw broke out of the plastic, so I think we'll need a new (or used but working) air box.
Which leads me to my next question: Does someone know a place to get an airbox at more or less reasonable price? I saw the one they're selling on pelican parts at ~420$, I also checked on ebay but didn't find any appropriate part right now.
Is there also an aftermarket box with a pop-off-valve already built in? That would be the best solution actually...

Cheers,

Marius

[klaucke]

You'll have to go with a stock box, or possibly glue yours back together. The pop off valve is aftermarket and (relatively) cheap: http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_fuelCI_pg4.htm#item12

[Jim Sims]

Moving the throttle pedal while starting will sometimes prompt a backfire that will blow the air box. I was taught (I have a '76 911S) to keep the throttle foot on the floor until the engine was started and running. I'm do not know if they ship to Europe or not or if the customs duty would make the parts too expensive however Parts Heaven is a good source of used Porsche parts at fair prices.

http://www.partsheaven.com/

Jim

[PCA7GGR]

If Parts heaven can't help you, try Jim at EASY, European Auto Salvage Yard - easypor@aol.com. Good luck and welcome to the joys of owning an older Porsche .

[sketchers356]

Asking for a cheaper price than Pelican on their boards? For shame

[Rufblackbird]

Marius,
Try checking the Pelican 911 Classifieds ...there are people parting out cars...like me, for example. If you're interested in buying an used one PM me.

[GrantA]

Welcome to the Forum. Here are some UK Porsche breakers that may be able to help (they are closer than the US).

www.porsch-apart.co.uk
www.porschepart.co.uk
www.porschebreaker.co.uk
www.pro-9.co.uk
www.douglasvalley.co.uk
www.partssource.autopage.co.uk

or you could try www.berlyn-services.co.uk I have found "Bert" very helpful.

They are probably shut for the festive season but should be open early in the New Year.

best of luck.

Grant
_____________________
1978 911SC Targa
1996 Volvo 850
1991 Mazda 323 Ex

[fred cook]

Marius,

There is a PP board member that lives in Oslo, Norway. His board name is "Ove". Why don't you try sending him a PM (private message) and see if he might know where to find a replacement air box. Getting one shipped from Norway to Switzerland should be a lot faster than getting one from the States.

Good Luck!

Fred Cook
'80 911SC coupe

[mdrohrer]

Hi guys,

thanks to everyone for helping me out on this! ;-)
Now that the air box problem is solved, are there other usual modifications (like a pop-off-valve) to the 2.7 engine (and surroundings) preventing us from further similar scenarios? ;-)

Cheers,

Marius