Ok 89 Carrera Cab that just yesterday was running fine now refuses to start. As it cranks I can smell fuel making it through the system and out of the tail pipe. I am concerned that it has become soooo flooded it will not start or the plugs may have become fouled. It did sit overnight and still not start this morning.

So here are my questions,

1. Where is the DME relay located on the Carrera? How does one check it to see if it is good?

2. How does one test the reference sensors?

One the possibility of it being flooded,

3. Can one simply pull a spark plug and have an assistant crank the engine with the spark plug out to check for spark?

I did pick up 6 Iridium spark plugs but have not changed them out. Is there any tricks to changing out spark plugs on the 3.2?

Any help appreciated at this point.

IPSC

 

Start by buying a new relay and changing it. If the old one ends up being good, you'll have a spare.

For the plugs-the spark plug wrench in your tool kit is the best way tool to use.

 

Don't quote me on this exactly, but I think a bad sensor will cause no fuel AND no spark. Same with a bad DME relay. It sounds like a bad DME, or a bad connection or ground. Still, it could be just a weak battery.

If it were my car, I'd start at the beginning. Make sure battery is fully charged, clean the battery clamps, clean the grounds, make sure the ICV (silver cannister next to throttle) is vibrating with the key in the "run" position.


Edit:
Try searching the old no start threads. Type this on either google or yahoo: [site:forums.rennlist.com "no start" 911] You can also do the same with Pelican "forums.pelicanparts.com". I don't have my Bentley manual right now, but you can also check for power at the coil, which is not controlled by the dme. It gets power directly from the key switch.

 

On a whim before I started trouble shooting I pulled a spark plug wire and stuck a new spark plug into the boot and grounded it out. While carefully holding the plug I had the car cranked over by a buddy and low and behold there was spark... So does this sound like fouled plugs? I will get one pulled later this evening and see what condition the plugs are in.

Also looking at the engine(lots of stuff in the way) are there any helpful hints to changing plugs on the 3.2 Carrera engine?

IPSC

 

Nice sleigh Gerry

 

get fresh plugs in there...

 

Could you tell if there was gas smell on the plug? Was the spark bright white/blue or was it weak? There is a spark tester at Sears made by Lisle Tool that works well. You just place it on the wire. It's cheap and looks like a pencil.

If you want to pull the rest of the plugs, then the factory toolkit wrench works well as Ed said. Otherwise there is a magnetic Hazet one that I hears works well.

Any time you disconnect a Bosh FI connector, try removing the spring wire clip first with a small screwdriver or a dental pick. Otherwise you risk breaking the connector. You can test for 12~12.5v at the injector connector(s). The Bentley manual outlines an excellect test program for the sensors, icv, etc.

 

Hummmm yes gas smell and I did the test during the day but the spark did not appear super bright.

I will head over to Sears to find the spark tester as well.

Alas the factory spark plug wrench is missing.... So I am forced to use a normal spark plug socket. Lots of fun there.

Yeah I at least know not to screw up the connectors. A Bentley Manual will be in the mail in the morning hopefully.

Thanks so far,

IPSC

 

If you go regular on the plug wrench, make sure it has a rubber collar to grab and hold the plug. Alto, make sure and tape the socket to a long extension. You don't want the socket to come off and stay down in the hole.

 

IPSC, a weak spark could mean that the coil is bad or not getting power. You should make sure that it is getting power. Do you have other weird electrical symptoms, say..strange window or radio operation, engine continues to run or starter sometimes does not turn over? If so, it could be a bad ignition switch.

Edit:
You can skip the spark plug tester for this test because you already pulled the plug(s) I think. The tester is a shortcut so that you don't have to go to that step if you hear a missing or mis-fire at idle.

There is a good way to test for spark, which involves attaching a test lead to the spark plug base with a spring loaded jaw clamp, and the other end of the lead to ground. That way you don't have to hold the spark plug in your hand. Make sure the ground contact is good (use good clamps and attach to the engine mount bolt or something large like that).

At this point, I suspect your coil or ignition switch. Still, you should clean your DME grounds and check for 12v power at the ICV connection, and the AFM, and the injectors.

 

Ok I "figgered" it out. Get this... the head temp sensor connector, (located on the drivers side in the engine at the top of the three electrical connectors) had broken and the plug had come loose. Now with that unplugged apparently the fuel injectors will DUMP fuel into the cylinders THUS fouling out the plugs..

I had not even considered this as a possibility. I simply noticed the plug looking not fully inserted while changing plugs. New sensor/connector is on the way.

So once I got the plugs changed and that connection jumpered she fired right up and purred like a kitten.


IPSC

 

WOW good Job ....

 

Hey congratulations! Duly noted on the CHT sensor.

 

i was just readinfg some old threads and had to laugh . my first ever tune up with my 911 consisted of an hour of getting my spark plug socket back because i didnt do this .. then i went to my tool kit in the car ..

 

I machined a slot for the wire in a deep socket when I did mine. What does everyone else do?