911 '78 SC wont start

[Brett]

Hi,

I broke the alternator belt about 8 miles from a service station at night on my 78 911SC. I drove it to the service station where the temperature stayed at half way and i had enough power with the lights on to turn the engine over.

I got home on the back of a flatbed and fitted a new belt 3 days later. I came to start it after the belt was fitted and it wouldnt start. it turns over well but will not start.

Full tank of fuel, and I get a high pitched whistle when i turn the ignition on . . .

Can anyone offer advice ???

Thanks.

[Bones]

Just to get this going, is there a strong smell of petrol? Pull a plug lie it on the engine and check for a spark.

[SilverPoly]

I don't think it was a good idea to even drive the 8 miles without a fan belt on your SC.

change your oil.., but you might have overheated the cylinders.

As for the whining it may be your fuel pump which would be the least of my worries.

[vash]

oil temp and head temps really differ? 8 miles is a long time.

you are going to have to go back to the basics, i would look for spark and fuel.

what kinda whining? keep us posted.

[Brett]

well - the whining is just the usual high pitch whistle from the ignition before i crank - and the 8 miles was at a steady 70 mph on the freeway . . . .

I stopped the engine - but managed to start it again to drive it on to the low-loader - then i drove it back off the low loader an hour later too . . .

not a strong smell of fuel at all when cranking ??

[Bones]

God I just felt sick Brett , I imagined you had driven at tick over speeds, still something that shouldn't be done unless you are in danger. If the engine isn't firing then you should smell fuel if there is petrol getting to the injectors. After what you said I would change the plugs for starters as they probably got super hot. If you get it to start then and it runs evenly , change the oil asap as has been suggested.

[vash]

brett, do you work on this car? i would pull a fuel injector and get it to spray. that is proof positive you are getting gas, and is easy enough to do. then, as suggested by some smart guys on this bbs, i bought one of those spark testers and it is easy to pop off a spark plug wire plug in the tester, ground it and have someone crank the motor. look for a fat blue spark. if you see spark and a good fuel spray......i dont know.

[Brett]

Good advice - i will give all this a go.

Is it easy to get one of the injectors out?

[Kemo]

ok...heres my guess.

Check to see if you are getting spark..i use my timing light to verify charge to plug as well as visual jump across the plug gap. as mentioned...just yank an injector to see if it sprays (as mentioned), its as easy as just pulling it out with your hand. then disconnect the cold start wire to the temp sensor up front left below the distiributor cap(could be hosed and causing some flooding) turn the key to the on position till you can hear the fuel pump whine. wait about 20 seconds and attempt to start. Dont run the starter motor for too long cause you could burn it up. If it doesnt start after like 20 seconds...let the starter motor cool off for about 30 min or so. Im no pro...but a friend of mine with alot more exp than me got my 78 running this way when it was acting up. If you got spark and gas...all you need it a place to compress and explode...if no results...you may need to do a compression test... Good luck.

[singpilot]

That 8 miles at 70MPH was 7-8 minutes with NO cooling over those cylinders. Book says Alternator light on? Engine off immediately...

[sammyg2]

You don't have to pull an injector. Just pull off the air filter, turn the ignition on and lift the air sensor plate a little. Don't hold it up[ very long or the engine will flood. As soon as you hear the injectors fire, stop. The fuel pump is supposed to turn on and the injectors will fire if everything is working right. You will be able to hear and feel the injectors open. If the injectors don't fire you have a fuel delivery problem and should check fuses and fuel pump relay.

Check for spark first. Then check for fuel with the above procedure. Then it's time for compression check. It is a possibility that you melted pistons enough to capture the rings and lose some or all compression. Hopefully not. A compression check wil ltell you if the engine is hurt or not.

When the alternator belt breaks you loose all cooling to the cylinders, heads, and oil cooler. The cylinders and heads will heat up very, very fast. the oil will also heat up but not nearly as fast.
8 minutes at 70 mph is probably enough to cook the engine. You may be lucky enough to get away with it, I'll say a prayer for you.

[Brett]

right - got a good thick spark by cranking and holding an ht lead near the crankcase.

Pulled an injector, but no fuel at all??

I managed to start the car and drive it off the back of the truck and on to my drive that night. I changed the belt and now i get no fuel delivery at all??? - any more ideas?

How can i test the fuel relay? - all fuses are ok. I cant remember hearing anything from the fuel pump before this problem - maybe i am just oblivious to the usual noise?

Where is the fuel pump situated so i can check the connections?

( - the high pitched whistle i can hear is the CDS unit. )


Thanks for your help so far

[Bones]

That explains the no fuel smell.......lol.........Fuel pump is in the luggage compartment, there is a relay too so check that it's in the front fuse box.

[stealthn]

Start alot simpler that that...charge your battery first.

[Brett]

Fixed it!!.

Tripple checked all electrics and realised that the fuel pump fuse had actually melted at the bottom loosing its connection with the fuse holder. replaced the fuse and hey presto - running like a dream again . . .

I knew she wouldn't let me down!!

Spare fanbelt in the glovebox now

[singpilot]

Buy a lotto ticket. You are really really lucky!

[Brett]

Thanks for your help people - Now I have found this site I will be back

[Bones]

Glad to hear that , change the oil and filter straight away you're probably running on chip fat!

[Brett]

Will do. (quite annoyed because i have just fitted a recon 915 200 miles ago so the oil and filter were new anyway!!!)

Thanks.