Greetings. I have a problem with an automatic 305 RS. As I came to a stop yesterday, the engine stopped. It didn't sputter, no warning, no guage indications that there were any problems - just stopped. It tried to crank it over 3 times for about 3 - 5 seconds each time. Oil guage showed pressure, temp was low (had only driven about 10 miles) voltage fine. On the fourth crank, it started up and sounded fine. I drove it home, and as I got home, it happened again. It seems to only happen when I come to a stop. So today I looked at some possible emmision systems problems. I checked the EGR valve (ok), changed most of the vacuum line (it was getting old), changed the cap and rotor. I'm getting spark and gas. This car has run like a champ before this. After doing the above, I tried to crank it but it wouldn't turn over. The car actually shakes a little bit and it cranks strong. I'm thinking it's not getting a computer signal somewhere. Every hour or so I tried to turn it over a few times to test this theory, and the car would start randomly, and then shut off after anywhere from 10 seconds to 2 minutes. The last time is shut off, it ran for about 10 seconds, then the rpms went down and up (to about 2000 RPM) really quickly, and then it stopped again. Is it likely that I have a bad computer (ECM)? Also, I went to the auto parts store and the lady showed me a part that is a "little computer" (as she called it). It looked like the HEI unit in the distributor cap, but had 2 metal prongs on one end (lile the HEI), but had female connectors in it - I think one had 4 round opening and the other had 2 round openings. I have never seen this unit and she told me it was under the hood near the passenger side firewall and that she had a similar problem and that was the bad part. Anyone know what part this is? I looked for it, and didn't find anything. I only looked under the hood (because that's where I was told it would be and it was getting dark - no need to take the under side of the dash apart @ 8:00). Any thought as to what the problem could be or if anyone can identify this "mystery" part and tell me where to locate it, I'd appreciate it. Thanks a lot.

 

I've never heard of the "mystery part". Are you sure it's getting fuel? Have someone else get in the driver seat, and turn thye key on while you get your ear as close to or on the gas tank as possible - to make sure you hear the pump running. I say this because, when my pump died, this was the same sorta thing - cut off, ran again for a few miles, cut off again, and never started anymore.

 

I've never heard of the "mystery part". Anyone that works at a parts store, and calls a part a cute name instead of the currect name - has no business in a parts store. There is no such thing as a "little-computer"! First thing, start going to a different parts store!

Are you sure it's getting fuel? Have someone else get in the driver seat, and turn thye key on while you get your ear as close to or on the gas tank as possible - to make sure you hear the pump running. I say this because, when my pump died, this was the same sorta thing - cut off, ran again for a few miles, cut off again, and never started anymore.

If it runs, let us know, and then we'll check something else. If not, then....

Next, try swapping the relay for the fan with the relay for the fuel pump, and listen again. If it runs, then you have a bad relay. If not, then....

Try running removing the relay for the fuel pump and running a jumper from the large orange wire to the brown wire in the relay's wire pack, then listen for the pump. If you hear it now, you need a new oil pressure sending unit.

 

Okay - I'm on board with the ditching the crappy auto store, but it was the only one I could walk to. I'll check for gas again, but it had a strong smell when I floored it while cranking the engine, and a normal gas small near the carb when I was just cranking it without touching the gas. The following from your post just confuses me:

"Try running removing the relay for the fuel pump and running a jumper from the large orange wire to the brown wire in the relay's wire pack, then listen for the pump. If you hear it now, you need a new oil pressure sending unit."

I'm missing the oil pressure sending unit connection. How could the oil pressure sending unit be the culprit. Now that you mention it, I have noticed my oil pressure "floating". When a take a corner hard, the guage will quickly dip down to between 0-25 psi, and then correct back to 50-60 once I'm through the corner. This is only when I'm cornering hard, and the oil pressure otherwise is usually tight between 50-60. Also, can you describe where the "relay wire pack" is.

Also, I checked the computer code and it keeps coming up "12 12 12 12 12 12 , etc." It will continue to do this until I turn the key off. I know "12" isn't an actual code, but if a sensor was bad, wouldn't it be captured in the computer? I forgot to mention this in my original posting.

 

The way the car is acting would suggest alot of things but i've seen this before on alot of cars and it ended up being the ECM went bad. I'd start checking sensors and relays first however.

 

what the lady handed you is an ignition module, it is in a way a mini computer since it has a pre programmed backup timing table in it; but it's main goal is to fire your coil and translate the ECMs timing advance. I would bet she had the problem isolated and that would've fixed it. The ignition modules do go bad and they can act like what you're talking about when they do. I HIGHLY doubt the ECM went bad before the ignition module so I would take the part stores advice and replace it. I would however replace it with an aftermarket, or an AC Delco unit. Good luck.
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Let me rehash what you're saying here, this unit had 4 female prongs on one connector, and 2 female prongs on the other one? Because ignition modules in the 87 up (small cap) cars have a 4 prong and a 2 prong plug. The only other thing I could even think of that being besides a different type of ignition module is the ESC. This controls swapping your timing from the module's start up timing to the ECM's timing, it's usually located behind the relays on the drivers side.

 

I'd like to thank you all for your knowledge. The problem was the ignition module. I took the ignition module off and had it tested. It tested fine under "cold" conditions, but failed under "hot" conditions. I put the new one (FYI - its located just under the distributor cap on a '92 V8 305 with tbi) and took it for a nice long drive. Before I pulled the ignition module, I cranked it over just to make sure it wasn't the fuel pump, and I could smell it fine in the carb. I didn't think that was the issue because I could smell gas and when I've had fuel pumps go in the past, they don't give you a second chance. Just a side note - with the new ignition module, I don't have any more of the oil pressure guage "float" that I had when cornering hard - maybe a possible warning sign/indicator if anyone else ever has this problem that the ignition module is going (maybe not.). Thanks again to all you guys. See you on the road.