Hi! So I've got a 1987 Buick Park Ave Electra, automatic, 168 thousands miles mostly hwy V6 3800 originally from AZ now in MN for 13 years. So the issue is that she stops running after 10-15mins give or take. There was a coolant leak. I think I fixed it but not sure cause when i added stop leak to the radiator (the pepper kind) she only ran 10mins then died, then after 10mins re started then died 10mins later. I just changed out the water pump, bottom radiator hose, thermostat & fuel filter. Still leaked so thats why I added stop leak. My car says its not over heating but my digital dash has been glitchy with the gas readings. The alternators good, fuel pump is good. The car runs & drives great except for it dying after 10-15mins give or take. So I let my dad change the spark plugs with my son (he didnt wanta learn from me lol) after that theres a gas smell in my oil, its not milky though. Could that be the reason? I thought it could be the fuel pressure regulator & injectors? Or crank shaft position sensor? Or the ignition control module? Or intake module? Or the harmonic balancer? Or a relay? Sorry for the long question, but old car so long history & I know you know thats not all of it lol! I'd really appreciate your help! All the great mechanics I knew sadly passed on. Also the shops I've called dont work on cars as old as mine? Crazy I know! 😯 I love working on cars thats why I do it myself. But I just know its something Im not seeing or thinking of to be able to fix her & I've put so much time, money, sweat & tears into her! I know she's worth it! Oh so I havent been able to find anyone who has a code runner. I've got one but its been years since I've used it & I dont know how to read the flashes for it. The check engine light used to always be on, now its off but if I drive her for the max time she lets me it does come back on. I dont know so I'll stop here. THANK YOU SO MUCH FOR READING THIS I TRULY APPRECIATE IT TONS!!! 😊
Sincerely, Jeanette Cranston
Probably the reason mechanics don't want to work on it is because they can't plug a scan tool in to see what's happening. Old-school sleuthing needs to be used and there's an entire generation of mechanics out there that has never dealt with that situation.
Frequently in that kind of situation some electronic component is heating up and failing. Crankshaft sensor are infamous for that kind of thing, but you're talking about nearly 35-year-old electronics and it could be almost anything.
A quick check to see if the problem is caused by lack of ignition or by fuel delivery is when it is refusing to run spray some starting fluid into the intake manifold. If you have spark the engine will kick over, telling you that it's a fuel system problem. If the engine won't try to fire up even with starting fluid you have no spark.
Also check the condition of the spark plugs, they have an important story to tell about what's going on inside your engine.
Thank you for your input I really appreciate it! I had planned on checking the crankshaft sensor. I just have to find it lol! I will definitely do the starter fluid trick. I wish I could up load a video of her starting & running till she dies so that might give a better idea? So I do have a old code reader it doesn't look like the ones that have a screen, it's just a small rectangle shape that says GM on it. I just haven't done it in years so I don't know how to read the codes when my dash flashes. But for some weird reason my check engine light that used to always be on suddenly went off & then only turns on after she's been running for a while. I don't get why that's happening now? Oh & there's one more thing I've tried to figure out, so when I go to lock the doors I have to hit the button 10 times to get it to lock & my dome light flickers. I've changed the alternator 2 times & the last time they told me that it was still good. Also I've had it checked but it still reads good? The battery isn't to old, I had it checked while in the car & he said that it was fine too. But all the guys before that said its reading bad, holding a charge but the machine says its bad? All the times it read bad was when it wasn't in the car. So do you think I should get another battery? I just haven't cause I've gone through a few with this car, & it's still starting. But then I'm thinking what if that's it? The car does have air ride & digital dash too. She does idle a little high about 10-11 when 1st started then goes down. Anyways sorry so long, I don't have anyone to ask questions or talk to about this and I'm really not wanting to give up on this car! She really does run beautifully! No rust due to being from AZ, only 2 owners (myself included) & 168 mostly hwy miles. Again Thank You Very Much!!! Sincerely, Jeanette Cranston
If the battery is more than a few years old and some testers say it's bad, I'd say it's time to replace it. That car was at the bleeding edge of the electronics revolution in cars and being so old it's bound to have issues with wiring and components deteriorating. A questionable battery could definitely cause problems as well.
This is probably the scan tool that you have or something similar, an OBD1 code reader, and this page has instructions for reading the check engine light flash codes without the tool if it's not working:
https://mechanicbase.com/trouble-code/obd1-codes/
The only thing I question on the above site is their recommendation to hook up a battery charger when turning the ignition on to read codes. If the charger is not putting out clean power (the older types don't) it could cause problems with the car's electronics. If anything I would use an old-style jump starter that can provide continuous power to augment the battery.
Ok I will fold & buy a new battery. Again lol! That's the exact code reader I have! I also have a key looking one too. I couldn't find where the GM code reader plugs in, but I'm guessing it's under the paneling. The key hole one is in plan view. Thanks again for helping me out again I really appreciate it so much!!! I will be getting to work on the car tomorrow. Thanks to you I know where to start! 
If you want I would love to keep you posted, then you'll know what was wrong with it. Thank you again. Sincerely, Jeanette Cranston
If you follow the link it says the OBD1 connector is usually under the steering wheel and shows a picture of it.
Definitely let us know how you make out!
So I've tried to get codes from the code reader but for some reason I cant get my check engine light to come on? But I did figure out 1 thing. So it takes a min to start. I have to put my foot on the gas, which I shouldn't have to. So I primed the car before starting it. Then it starts, so definitely a fuel pressure issue. I just dont know if that would make it run just fine but then die after 10-15mins? And when I tried to get the engine light to come on it started leaking antifreeze in a completely different spot than before. I think now its coming outta the radiator on the driver side. Plus I'm not trying to run it to long cause of the gas smell in the oil. Oh & after it does start it does smell like gas. I wanta say rich gas smell, but I'm not sure if that's accurate?
Hi! I had a question for you! If I'm having to prime my car before I'm starting it. It's leaking antifreeze really bad even when not running? So I know to check my fuel filter ect. But I'm wondering if I'm having a issue with going through battery's because of a bad voltage regulator? Was wondering about your thoughts on it? I'd really appreciate your help!!! Thanks! Sincerely, Jeanette
As you said about the priming to start issue, that points to a problem with fuel delivery. If your alternator had a bad voltage regulator that would show up by measuring voltage across the battery while the engine was running. Should be close to 14 volts (like 13.5-14.5 volts). Of course if you are leaking antifreeze that's yet another problem that needs to be checked. If you're lucky it's just something like a leaky lower radiator hose.
Thanks for your advice, I really appreciate it! My battery is at those levels. As far as the antifreeze leak goes I did change the bottom radiator hose but it doesn't appear to be leaking from any hoses or the radiator & I know it's not the water pump cuz I just did that, so not sure where it's coming from? I think I'm gonna just bring it into this shop I found $45 to diagnose the car. I feel like it's a guessing game, and because I can't do the code reader cuz my check engine light won't come on that's been on forever suddenly goes off?!?! I really don't want to throw more money into it since it's like a guessing game & I wanta make sure it's still worth it. I hope it is! Fingers crossed!😊 I know it's probably something very small it's very frustrating though! Thank you again for your help! It really does mean a lot!😁 Sincerely, Jeanette
Well, the gas in the oil might be your best clue. I would focus on the possibility that the engine is running too rich, as per your suspicion of the fuel pressure regulator and/or injectors. Also make sure your battery is good. Good luck.
Thank you for your input. That was my 1st thought. I just couldn't find the parts for such an old car. So I will definitely try to find those parts.
The only question about the gas smell in the oil is that it didn't have that till after my dad & son changed the spark plugs, so I didn't know if that could make gas get into the oil if done wrong?
It could be from trying to start it with no spark. You have a certain amount on "blow by" past the piston rings. That's usually inert combustion gasses but without spark it's raw gasoline.
When you correct the problem, change the oil
ok makes sense. Thanks you I kept thinking that the more I ran it the worse it would get with gas being in the oil. Which I was only trying to run it long enough to get the check engine light to come back on again so I could check the codes. I really dont understand why it's not on now? It's been on the entire time up until I changed the bottom radiator hose. Thanks again I appreciate your input.
If they used the wrong plugs or if they are not gapped correctly it could cause an incomplete burn.
Thank you for your input I will be checking that out today!
Sincerely, Jeanette Cranston
I think @chucktobias is pointing you in the right direction. Those old 3800's were bulletproof but when they behaved like that it was often because of a faulty crankshaft position sensor or because water got into the crankshaft position sensor's electrical connector and corroded.
I agree, thank you for reading my post & for your feed back. I really appreciate it.