In a jam, expertise requested (82 930)

Cain-MO · 04:52 AM

First, I have been on these boards for years, I just can't remember the password or email address I registered with.

I have a gorgeous 82 930. I have had it for two years. I put less then 1,000 miles on it each year. I would regularly drive it about 100 miles a month or so, until I deployed last year. When I returned in Jan, I decided to sell the 930 and find a nice 951.

Jump ahead a few weeks. The 930 is sold to a gentleman in Texas. The car transport was to pick the car up this morning, however, I took the car out of the garage to warm it up, drove it around the block, let it idle for about 3 mins. I did not drive it hard, didn't even go over 25 mph.

I was about ready to shut the car off when the RPMs dropped, the engine shut off, and then backfired with a single pop.

I attemped to restart the car and it only spins, does not turn over.

I contacted the buyer and explained the situation. The silver lining is this happened BEFORE the car was picked up, as if the buyer decides he wants his money back, obviously I would do that. But if it broke when it got there, it would be hard since it was out of my possession. Silver lining I suppose.

The first thing that popped into my nugget was rod bearings, but that's mainly because I had to deal with them once in a 944. I know very little about the 930 engine (which is why I was getting out of the 911 world and back into something I was a bit more comfortable with, the 944).

Given those symptoms (rpm drop, backfire, no start just spins) what can I potentially be looking at? I am bracing for the worst, so looking for brutal honesty.

Kind regards,
Matt Olde

jwasbury · 02-28-2010, 06:01 AM

Sounds like an electrical issue to me...probably fuel delivery, or perhaps ignition system.

Check fuses in the front hood area. Fuel pumps run off of a single 20amp fuse (assuming no one has messed with the factory wiring). There is a relay in the engine compartment which is supposed to shut off the fuel pumps in an overboost situation. This relay causes a lot of trouble for people so you might check that as well.

Do a search of this forum for overboost relay, or maybe just relay and you find lots of threads addressing the topic.

Good luck with it.

torresmd · 02-28-2010, 07:15 AM

I had a similar issue. I replace the yellow relay in the engine compartment and all has been good ever since, knock on wood!

wjfk32 · 02-28-2010, 10:39 AM

Sounds like the fuel head gumming up. It happened to me when not driving the car. Same symtoms/just died. Starving for fuel. Also chk all possibilities as mentioned. Try marvel mystery oil. Worked for me.

turbobrat930 · 02-28-2010, 10:46 AM

I would say either the fuel head is gummed up, or what I really think it is is the ignition box. Permatune, or whatever they call it. Check to see if you have spark. Usually if the piston in the fuel head gets stuck, you will have the opposite problem... too much fuel, and it will come running out of your exhaust.

Cain-MO · 02-28-2010, 10:54 AM

Gents, THANKS. I will post back with results from the above "checks".

Thanks,
Matt

gsxrken · gsxrken's Garage

Quote:

Originally Posted by turbobrat930

I would say either the fuel head is gummed up, or what I really think it is is the ignition box. Permatune, or whatever they call it. Check to see if you have spark. Usually if the piston in the fuel head gets stuck, you will have the opposite problem... too much fuel, and it will come running out of your exhaust.

+1 on checking for spark first and foremost. Pull a wire and put a spare plug on the end of it, and ground the threads of the plug while a helper cranks the engine. Make sure you have a decent zapp-zapp going on there.

And turbobrat, your signature reads like my long-term Christmas list. Nice build.

JBL930 · 02-28-2010, 11:37 AM

Although the above is probably right, have a quick look and see if there is a lot of petrol in your airbox. I know when my WUR went, and the diaphragm split, the engine died and it backfired. Just a thought

turbobrat930 · 02-28-2010, 11:48 AM

Quote:

Originally Posted by gsxrken

+1 on checking for spark first and foremost. Pull a wire and put a spare plug on the end of it, and ground the threads of the plug while a helper cranks the engine. Make sure you have a decent zapp-zapp going on there.

And turbobrat, your signature reads like my long-term Christmas list. Nice build.

Thanks... It has taken a LONG time to get here..... and I still am not done...

Cain-MO · 02-28-2010, 12:24 PM

From what I can tell, I do not have a spark.

I checked fuses, and relays, and from what I can tell they are fine. I swapped the fuel relays with the window one, and vice versa -- the windows still operate.

After a few cranking attempts, I smell a decent amount of fuel, so I'm guessing it's getting fuel and I probably flooded the cylinders...

I checked to see if there was spark (pulled the fuel pump relays so as not to continue to flood the engine) and from what I can tell I am not getting spark.

What is the next step as far as no spark? I did not see a fuse or relay related to the ignition system.

Thanks,
Matt

turbobrat930 · 02-28-2010, 12:36 PM

Quote:

Originally Posted by Cain-MO

From what I can tell, I do not have a spark.

I checked fuses, and relays, and from what I can tell they are fine. I swapped the fuel relays with the window one, and vice versa -- the windows still operate.

After a few cranking attempts, I smell a decent amount of fuel, so I'm guessing it's getting fuel and I probably flooded the cylinders...

I checked to see if there was spark (pulled the fuel pump relays so as not to continue to flood the engine) and from what I can tell I am not getting spark.

What is the next step as far as no spark? I did not see a fuse or relay related to the ignition system.

Thanks,
Matt

If I had to guess, it is going to be your CD ignition box... see here...

Pelican Parts - Product Information: 930-602-702-00-M46

Someone might be able to post up the procedure for checking the unit to see if its bad... I have got to be getting to work... I hope you get to the bottom of it...

It should be located on the fuse/ electrical panel in the engine compartment (left side)

JFairman · 02-28-2010, 12:41 PM

Check that the 6 pin plug in the bottom of the CDI is in all the way.
Sometimes the locking tab on the side of each individual female spade terminal in the 6 pin plug bends back and even though the plug is inserted all the way it's possible one or more of the spade termainals aren't pushing on to the male ones on the CDI. Peel back the rubber boot to see if all of them are engaged.

Make sure all the small wires are on the coil on tight and try another coil because the oil filled ones don't last forever mounted upside down on the fan housing.

The green trigger wire from the distributor is known for becoming a problem. It goes into the harness and reappears in the 6 pin plug that goes into the CDI.

Then there's the silver colored ignition delay relay next to the rear window defroster relay on the rear relay panel and the rev limiter relay on the floor under the driver seat that could be doing it.
I suppose even the ignition switch or maybe the alarm system controller could be it.

A930Rocket · 02-28-2010, 06:04 PM

Matt

fo you hear a high pitched whine with the ignition on? That should be the CD box. No whine usually means the box is bad.

I can send you my spare to swap out to see if that's the problem.

PM if needed.

Cain-MO · 03-01-2010, 02:52 AM

I do hear a high pitch whine (like a ringing in your ear) when the ignition is on, coming from the engine compartment.

A930Rocket · 03-01-2010, 05:13 AM

Sounds like CD box is getting power.

Did you check for spark at the plugs or the coil wire? Check both to try and narrow it down.

If no spark at either, then check your coil and the coax wire to the CD box. Maybe tap the 1"x3"x3" silver box mentioned above. Can it be jumped guys? All the wiring under the drivers seat can be removed and it will run. Mine's been removed for years.

wjfk32 · 03-01-2010, 05:36 AM

It souNds like its getting power/SPARK...My mechanic was going nuts in the beginning when he couldn't find the problem..It sounds like the fuel is being blocked..The fuel head is a pain in the neck. GL.

smokintr6 · 03-04-2010, 07:24 AM

Spark can also be checked with a timing light.... Very easy to do and requires no tools (other than a timing light). It will take you 2 seconds, and an assistant. If the light doesn't flash, you have no spark....