Help Needed - Carrera Won't Start

[tom1394racing]

A couple of months ago I installed a new Optima Red Top battery in my brother in-law's 1986 3.2 Carrera Cab. His old battery was dead. While I had the car, I also did the annual tune-up. All went well and after completing the work, I enjoyed few weeks of open top motoring before returning the car to him.

Two days after he gets the car back he called and told me it won't start. He was able to drive for 1 day and then could not start it the next. He told me it would crank but wouldn't fire. He also told me that if he wiggled the positive wire leads to the new battery, he could get it to start. That "trick" worked for him once or twice and then no longer.

I had the car flat bedded to me last week and inspected all the hot leads to the battery positive terminal. There was some corrosion so I replaced them all but still the car would not start. I checked a spark plug grounded against an intake runner and found no spark.

All other electrical systems seem to work and I have 12 volts at the fuse panel in the rear of the engine compartment. All fuses are good.

Any suggestion would be very much appreciated.

Thanks in advance.

[PCA7GGR]

DME relay?

[tom1394racing]

Is it under the seat?
How do I check it?

[Zef]

Under the driver's seat...A black small box...knock on it a bit with a screwdiver and recheck starting...The weld inside become brittle with time...replace it...

[Joe Bob]

Pull battery terminals, clean and reinstall. Use water and baking soda solution.....OUTSIDE of the trunk.

[tom1394racing]

I already cleaned the battery terminals when I replace all the electrical connectors.

[Joe Bob]

Then the check the terminals leads themselves and the connectors. Also check where they connect at the starter. If you have a "Fluke" or other such voltage tester, check the volts at the starter.

With a 3.2 it's also good to have a spare DME relay.

[S ECU Repair]

do you have injection pulse ....? check it with a noid light like the one in the picture ,if you have injection most likely your Dme relay is bad .

[Wil Ferch]

I found a similar problem that was caused by green corrosion under the big fat positive lead to the battery right by the terminal connector. Wiggling the wire allowed the car to start. Upon investigation, and after I disconnected both leads to the battery..I peeled back the insulation , the green corrosion seemed to go back about 4-6 inches. I cleaned and scrubbed the wires ( of course I had to cut off the terminal)... and I treated the cleaned up area with conductivity enhancing grease. Wrapped the wire back up and added a new positive terminal and all has been fine since.

[tom1394racing]

OK Guys

Thanks for the advice.

i'll check the battery terminal leads again and try rapping on the DME relay.

I'll let you know what happens,

[Jeff Alton]

Rapping on the relay will hardly rule it out as a cause of the problem. When you crank it is the fuel pump running? Is there fuel pressure? When the relay fails, the pump will not come on.
The relay is cheap, and not a bad idea to carry a spare, so get a new one and use that as the test of the relay.....

Wil brings up a good point about electrical connections. Just because they appear ok, dig a little deeper and who knows what will turn up.....

cheers

[450knotOffice]

My money is the DME relay. These things fail regularly. If a person drives a 3.2 Carrera, it's not if the DME relay will fail, it's when.

[tom1394racing]

Thanks Guys

I just ordered a DME relay from our host.

With the key in the full on position, I cannot hear the fuel pump running.

Are the Carrera pumps loud enough that I should hear it from the cockpit, or do I need to go under the car and feel it?

[DW SD]

Originally Posted by tom1394racing

Thanks Guys

I just ordered a DME relay from our host.

With the key in the full on position, I cannot hear the fuel pump running.

Are the Carrera pumps loud enough that I should hear it from the cockpit, or do I need to go under the car and feel it?

Tom,
I don't think the fuel pump comes on until the engine is cranking. It would be hard to hear both, though you can have a helper watching a test light at the fuel pump or at the lead to it from the DME relay.
A helper should be able to feel the vibrations, too, actually.

Doug

[UK Carrera]

My money is on one of the flywheel reference sensors having failed.

[tom1394racing]

OK

So I can check the fuel pump by either having a helper feel it while the engine cranks or by checking the voltage across it while the engine cranks. If the fuel pump is not running or if there is no voltage then a likely culprit is the DME relay.

I suppose I could confirm that the problem is the DME relay by checking the voltage into the relay with the key on.

If I have voltage at the relay and no fuel pump and no spark, it is most likely the relay.

What do you think?

[DRACO A5OG]

Sounds Correct, you need a spare DME relay anyways. $30

I suggest getting a new DME Relay and see if that fixes the issue.

[nesslar]

Definitely.
My car wouldn't start one afternoon until after trying for some 45 minutes. I drove home and the next day it wouldn't start at all. New DME (my spare) and problem solved.
I looked at that DME that had died (took it apart) and noted that at the point where they were bent upon manufacture, a couple of the "L-shaped" arms that extend from solder joints to the connector pins looked "cracked" at the 90-degreee bend. Just the combibation af age, current flow and built-in stress I suppose. I wonder if that is where a lot of these fail? All else looks real solid.

[tom1394racing]

nesslar

Did you replace the DME unit or the DME relay?

[Zeke]

I'm sure he meant the relay.