500, 472, 425, 368 Discussion, Need some help about my stalling car in Cadillac Engine Technical Discussion; I have a 78 deville I just replace stock engine, with a 472 old model engine.
It stalls after traveling ...
I have a 78 deville I just replace stock engine, with a 472 old model engine.
It stalls after traveling 60 mile. I just get a rebuilt carb. still have the same problems. Any one find of how to fix this problem on there car.
Off hand I can think of a few things to check.
1.) check all vacuum lines carefully, including the pcv hose and valve. Look for hidden cracks.
2.) if you don't have electronic ignition, replace your points and condensor and set your dwell carefully (30 degrees or .017").
3.) Check distributor rotor, cap, plugs and wires carefully or just replace.
4.) Check your ignition timing (tends to become late as timing chain wears).
Good point Tripleyellow. A pressure test is in order. About 5 to 6 psi is good.
Since we are talking fuel systems, it would be a good idea to check everything leading to the fuel pump as well. Fuel lines (steel and rubber) check for cracks. Also check the rubber fuel hoses that connect to the gas tank (these can crack and suck air without leaking gas).
I think I may have fix my stalling problem still need to drive a few more days to make sure. I did like U said check plugs " i replace the old plugs they still look good" I then check my plug wires my number 7 plug wire had been burning itself inside the wire boot, it had no spark tip and the plug probly wasn't firing. I take it a part cut back the rubber to let the spark to the plug tip connect. I think over the travel time the gas was building up in that cylinder and stalling the car out. maybe still an uneducated guess.
Thanks Guys for the help and list of things to do.
Good work. You can't have reliability with old plugs and wires. That's why I say replace if in doubt.
Plugs can "look" ok, but do not fire reliably, same goes for ignition wires. You can check ignition wires with a good ohm meter. Several thousands of ohms is ok for resistor wires, if you find any with infinite resistance or other obvious problems you may as well replace the set. And, like I say, you may as well replace the rotor and distributor cap and points (if you have standard ignition). These items are consumable, and need regular replacement intervals.
Many years ago I was asked to look at a engine with similar problems. It would always start up and run fine, but would die after warm-up. This problem was very consistant. It would always restart after a cool down. I traced it to bad ignition wires. Of course I replaced all the items mentioned above and the problem was solved. In my experience this set of symptoms for bad wires is unusual, one would expect the typical symptoms of hard or no starting, poor driveability and/or rough idle. That's why one should never overlook anything or assume anything.
An old thread, but I have a similar problem on my '76 Eldo. After it warms up for awhile, it will start to stall on acceleration. Goes back to idling fine.
I was thinking it might be the insulating grease drying out between the distributor module and the distributor body, but wouldn't that cause it to shut down completely?
It is odd that it only happens once the car has been well warmed up. Wouldn't bad wires cause a problem all the time? The other confusing aspect is it will stall a little, then run fine, then stall some more. Odd.
Any help would be appreciated, particularly in the diagnostic process. I would prefer to trouble shoot without replacing parts.
If you think it's not fuel related but ignition. You could remove the ignition module from the distributor clean the connectors and use pliers to tighten the female ends, put a coating of silicone dielectric grease on the bottom between the module and distributor. Have you replaced spark plugs, wires cap and rotor? If your cheap you can clean and regap the plugs if they're not in bad shape. If it's not ignition but fuel related I can give you some tips on fixing it. Like testing to see if it's the choke(hold the choke open by placing a screw driver down the carb between the choke plate and air horn. Then try starting and take a test drive). Send me a message with any other info on your car. Like what parts have you replaced, when does it stall, is it weather or engine temp related, black smoke out the tail pipe when starting or going uphill, does it restart right away or do you have to let it cool down a while etc...
Thank you for the advice. Just getting back to working on the car. Too many projects.
I thought the choke closing theory was logical, particularly since I backed it way down to fix a fast idle problem when hot and a closed choke would cause the same result.
So I wired the choke open and went for a drive. It started doing the loss of power as soon as the car warmed up (about 10 minutes), while I was going 70 down the hwy. I drove back to the garage, and it did the on and off loss of power the whole way.
Since air starvation seemed logical, I thought the air cleaner snorkel could be getting blocked from the heat riser, so I flipped over the top of the air cleaner cover (so the air filter is open to the engine compartment) and went for a drive. Same loss of power.
Another post mentioned clamping the return line from the charcoal canister back to the fuel tank. I did that and it still lost power after a short drive. I just read the other thread, and I was supposed to clamp it after the fuel pump, so I will try that next time.
To your questions, I do not think it is ambient temperature related, but engine temp. Not overheating, just warmed up. No smoke out the exhaust, and the engine does not die, unless I keep my foot in the throttle. I just let off the gas, the engine runs fine, then I try giving it more gas. It will either stutter some more, in which case I feather the throttle, or it runs Ok for a few more seconds. The engine will always start right back up regardless if I turn it off with the key or stall it out by holding down the throttle when it is stuttering.
Replaced parts: I have not replaced the plugs, wires, cap and rotor, as they seem relatively new. I have replaced the coil (though it did not solve the problem), run new fuel lines, fuel filter, gas tank, sending unit, rebuild the carb with new parts, cleaned the module and put on new grease.
I have set the timing, idle and adjusted the mixture so the car runs great before it starts the stall problem.
Currently I am leaning towards it being a fuel pump problem and thinking about installing an electric pump, since it would also speed start-up after the car has sat for a month or two. If people feel that it could be the cap/wires/plugs, then I will swap those out as well.
Scraped Knuckles you mentioned in another thread that it could be a clogged cat? That would seem to cause similar symptoms. What is the test for that?
Automobile(s): 58 Coupe Deville, 77 Coupe deville, 90 Deville
Re: Need some help about my stalling car
This stalling problem could be the pickup coil also, but if you are replacing the entire dist that would be included. Any type of eletro magnetic coil can act up when warm but then start working again when it cools a bit. Just another suggestion. Of course if the 472 has points, disregard the pickup coil advice.
Automobile(s): 1977 Coupe (blue), 1977 Coupe (yellow), 1977 Coupe (green)
Re: Need some help about my stalling car
Another possibility is that when the engine temperature controled actuators allow vacuum to the dashpots, the dashpots may have torn or cracked diaphrams. You open the system to vaccum leaks and the dashpot doesn't function as it should. If you have a SM, you find the dashpots have a set vacuum they should hold for a set amount of time.