dam thing won't start!

[amschnellsten]

I tried starting my 84 today and cranking but nothing. I always had to put the battery on a charger before starting it in the morning. It sits fro weeks at a time. The last time I charged it it ran wonderful for the first half hour then I got stuck in traffic and it started missing and bucking and did not want to hold an idle. I since changed the cht sensor and started it and it was fine as long as the charger was on the battery. I checked the voltage before while running and I was getting 14.2 at idle. I just put a new optima battery in today and it cranks but does not seem to crank fast enough. I noticed when I would try to start it previously it would not start unless the tach bounced a little, and now the tach is not bouncing. I would think the car would start even if it cranks just a little slow. Could I have weak reference sensors and the extra voltage bumps them alive? I think I am getting fuel because I hear the pump when cranking and it smells a little "gassy" but I do not think I am getting spark. I felt under the seat and the dme relay is clicking but I have never replaced it. I am not real familiar with my 911. I had a 928 s4 and a heavily modified 944t and my 944 had reference sensor and klr brain problems. That car I could jump two wire with the klr unplugged and I could get it started. What should I check for? help!

[slodave]

First thing to check is the DME relay. It's the dual relay next to the DME, under the drivers seat. A quick check, is to tap the relay a bit and see if that does the trick. Anyway, you should always have a spare in the glove box. You can take the cover off of the existing one and resolder all of the joints.

Dave

[amschnellsten]

I will pull the relay and check it out. Is it normal for the tach to bounce slightly while cranking? Is that showing the signal to/from dme/refereence sensor?

[slodave]

Originally Posted by amschnellsten

I will pull the relay and check it out. Is it normal for the tach to bounce slightly while cranking? Is that showing the signal to/from dme/refereence sensor?

I can't answer that - I don't know.

[amschnellsten]

does anyone know if the tach should bounce slightly while cranking. I ordered a starter for $105 and a dme relay for $14. I figured they are both cheap. I am thinking maybe the starter is worn and pullingtoo may amps while cranking. Is this feasible.

[rick-l]

Originally Posted by amschnellsten

I tried starting my 84 today and cranking but nothing. I always had to put the battery on a charger before starting it in the morning. It sits fro weeks at a time. The last time I charged it it ran wonderful for the first half hour then I got stuck in traffic and it started missing and bucking and did not want to hold an idle. I since changed the cht sensor and started it and it was fine as long as the charger was on the battery. I checked the voltage before while running and I was getting 14.2 at idle. I just put a new optima battery in today and it cranks but does not seem to crank fast enough. I noticed when I would try to start it previously it would not start unless the tach bounced a little, and now the tach is not bouncing. I would think the car would start even if it cranks just a little slow. Could I have weak reference sensors and the extra voltage bumps them alive? I think I am getting fuel because I hear the pump when cranking and it smells a little "gassy" but I do not think I am getting spark. I felt under the seat and the dme relay is clicking but I have never replaced it. I am not real familiar with my 911. I had a 928 s4 and a heavily modified 944t and my 944 had reference sensor and klr brain problems. That car I could jump two wire with the klr unplugged and I could get it started. What should I check for? help!

I watched my 88 tach as I started it. It cranks for a short period the tach kicks and then it starts and the tach pops up.

I don't think that should be your first trouble shooting step however. Whatever happened to seeing if you had spark as the first step?

Doesn't run without the charger WTF? Was the battery fully charged? Is your new Optima fully charged? I see the Loren vulture circling...

[amschnellsten]

it runs without the charger but crappy like it isrunnung without a charged battery. The new optima is not full charged. on an amp test it goes in the yellow on a snapon meter.

[amschnellsten]

no spark at all. changed the dme relay and checked the distributer cap rotor and play. Iam going to check the coil tomorrow. Any other suggestions?

[rusnak]

I agree first thing to check is the DME relay.

After that, you must make sure that you are getting at least 10 volts to your fuel injection harness, more if you have corrosion on your connections and grounds. My suggestion is to take the battery out, clean all of the battery connections, cables, and clean your grounds with a small brass brush. Put everything back together, and when the battery is fully charged, my bet is it'll fire right up and run fine.

[Ron.G]

Sounds like the battery to me.
The tach usually bounces around due to low voltage. Maybe you need to get the battery up to a full charge and then give it a try. You also might try another battery, in case your new one has issues.

just thinking out loud.

[S ECU Repair]

I will check injection pulse at the injection harness with a noid light.

[Lorenfb]

Check here for troubleshooting info:

www.systemsc.com/diagnostic.htm

It should take about 5-10 minutes to isolate the problem.

[billybek]

Service truck won't start. Nissan won't start. Haven't tried the 3/4 ton yet.
Porsche will start though... It is -35 deg C ( -40 deg F =-40 deg C) and the SC is the lone occupant of the heated garage....

[rusnak]

minus 40??? Are you sure you don't live on Jupiter?

[Trog]

Originally Posted by billybek

Service truck won't start. Nissan won't start. Haven't tried the 3/4 ton yet.
Porsche will start though... It is -35 deg C ( -40 deg F =-40 deg C) and the SC is the lone occupant of the heated garage....

But it's a dry cold!

[3.2 CAB]

Originally Posted by Trog

But it's a dry cold!

I think that means, just only one ball falls off.

[GH85Carrera]

billybek, is it true that at -40F a cup of hot water will freeze before it hits the ground if you throw it into the air? I don't ever want to be where I could test that myself so I will have to ask others.

[billybek]

I don't think that is true, but I think if you spit a long distance. that might freeze.
Not a good idea to stick your tongue on your bumper if the car is parked outside!!!
Most of my day was spent just trying to get things running...
The SC has a new (cold) room mate. Had to push the GFs X-Trail into the garage...
She gets a little cranky when her mobility is gone... Hope Wed is a better day...
Sorry about hijacking the thread!!

[amschnellsten]

ok still no starting! I have no spark. I replaced the dme relay, checked the coil, grounds look fine ( I have not cleaned them yet but looks like there is nothing to clean), cap and rotor look new, no play in the shaft. are reference sensors the next logical step? Can i check them with a volt meter. I sold my oscilliscope but I can borrow it back if absolutely necessary. I have not changed these before in a 911, I have changed them in my 944t a long time ago. Is true that they cannot be changed without pulling the whole bracket with the motor in? Does anyone have a write up of this?
thanks

[dshepp806]

How did you test for spark? As well, how was the coil checked?

Best,