Hello all

since last week my 78 Cadillac Seville (350 ci / petrol) runs with misfires and unstable idle. I checked the spark plugs and 2 of them where wet with petrol and black. As i had no short spare spark plugs, i cleaned them and placed them back and had the still the same problem. So I checked the wires to the distributor, they are not new, but mights still be usable. I removed the cap from the distributor and cleaned all contacts and the contact on the rotor and placed everything back, where it belongs.

Since then, the car doesn't start anymore, what could have gone wrong?

thank U for all replies.

 

If the plugs were wet then it is possible that you have a flooding situation. If the plugs get wet it will be very hard to get started. If you have the EFI the injectors are delivering too much fuel, pressure regulator malfunctioning or bad injector, what type of distributor do you have ?? Is it the points type or electronic.

 

How do I recognize the difference?

 

Is the coil on the top of your distributor cap or is it a separate round object mounted on the top of the engine?? No familiar with the 78 so not sure if they had electronic ignition then.

 

O.K. I just answered my own question. In my manual it says the electronic ignition started in 75 so that's what you have. There is a lot of things that could be the no start issue within the distributor. Are you getting good spark at the plugs?? Pull one plug and put the wire boot back on and then hold the plug against the block while someone cranks the engine to see how strong the spark is. At least then you will know where to go from there. You can also have a new set of plugs ready to install so you will know the are all dry and then see if it fires up.

 

hello

It is the one with the coil on top.

I took the used rotor and cap and even some of the wires from the caprice engine and the car started again, but it was not running smart, but it was running at least.

Today I replaced the distributor cap, the rotor, the coild, the sparks and all wires with new ones, but the problem is still the same, except that the sparks are only sooty and not wet anymore. when I start the engine it runs but as soon as I change to R or D, it switches off, if I don't press the gas down and the misfires are still there. As far as I can see from a visual check, the fuel pressure is oK (about the same as it alwys was).

as the problem is still on the same 2 cylindres as before, can it be related e.g. to the injectors or even the ECU?

how do I check the injectors without removing them?
how do I check if the car has a problem with the electric ground?
how do I check the fuel pressure without any special tool?

The only part I didn't replace now, related to the 2 cylindres, are the injectors and the maybe the ECU, or am I completely wrong?

has anybody another idea about what to check?

 

Was just looking in my manual in the troubleshooting section and I came across this info.....On the 78 Seville stalling after being started one of the causes is the Idle Air Compensator Solenoid. Some of the things causing rough idle are...bad temp. sensor or wiring,disconnected or leaking manifold absolute air pressure sensor, poor connection or open circuit in the air temp. sensor. Hope that helps a little bit.

 

this sounds interesting. Which one is the air temperature sensor? there are 3 wired sensor at the engines front, one on top of the water pump (coolant temperature sensor) and 1 at each side of the thermostate housing and there is another sensor between the spark plugs at the driver side (left) of the engine, could this be the air pressure sensor?

 

My best advice to you is if you plan on keeping this car for a few years then you should purchase a Cadillac Factory Service Manual. Then you will have all the diagrams and info to read so you can understand and fix these issues. They are truly worth their weight in gold. These cars have so many subsystems that run behind a main system that you cannot do a thorough job without the manual in hand. Happy motoring will follow.

 

...I ordered it already, thank you...

hello all

after changing the entire inlet, the carburetor, the fuel rail and all injectors,
I have a good battery, fuel on the fuel rail and enough pressure, the fuel pump is working, 2,5-2,7 ohms on all injectors, there is enough air and enough fuel, but the car still doesn't start at all,

As I replaced the sparks, the spark wires, the distributor and rotor, the injectors, the fuel rail, the carburator, all sensors on top, I have no idea, why the car does not start. I once had a similar occurence already, when the connection to a sensor, located on the driver's side cylindre head, between the 2 rear sparks (1 wire, the sensor is mounted on an about 8 inch long screw), broke off. Can this be related to this sensor, as I only grounded the wire the last time and it is still only grounded?

I didn't find out, what this sensor is used for and I couldn't find a replacement for it so far...

any other good idea? thank you in advance

Bruno