VS V8 over fueling

[Holden439]

Have 304 motor with cam in it that come with tuned memcal I went in car and was running good, I got motor minus intake dizzy etc put motor in my car runs but over fuels plugs fowl any thoughts?

 

[Deuce]

My first thought is that you forgot to hook up the map sensor vacuum line.
Check that and report back.
I've seen it before where it runs with vac line disconnected but runs pig rich.

 

[someguy360]

As deuce said, start with the easy stuff first, if the map sensors not connected it will run so rich it will foul plugs almost immediately.


Did you set the timing in diaganostic mode as well? If you put the dizzy in then just whacked a timing light on it, your not going to be correctly setting your base timing.

You need to have the engine idling, then bridge pin 5 and 6 on the diagnostic port under the steering column, the engine light will start flashing and thats when you check and set your timing to 10 degrees BTDC, any other way and the timing will be out.

 

[Holden439]

The vacuum line to map sensor is hooked up and sensor is plugged in. At first I didn’t know how to set base timing properly but found how to do it on here. But have pulled dizzy out lined up properly put in and set base timing to 10 btdc. But still fouling plugs and oil going fuely, when you rev it stays at 1100rpm for a bit before dropping back to below 1000rpm. The intake setup injectors etc and dizzy cap and leads were running the previous motor in car fine. But have new dizzy cap and leads and have tried that and does same thing. Can timing still be out some how ?

 

[Deuce]

Pull the vacuum line off the back of fuel reg. Is it fuel wet down the line?
Probably not enough to go pig rich, but a possible issue not present on last vehicle.

Leaky injector? Or different flow injectors?

 

[gtrboyy]

Fault code check first for anything obvious.

Most likely you've missed something or made silly mistake so go over everything twice even unplug & plug in again to be sure.

Guessing you're using same type of manifold that engine was tuned with & car it came from was same model vs?

 

[WitiTune]

Coolant temp sensor is a common fault of 304s, there is 2 in the front on the engine, the single wire controls the temp guage, the 2 wire is coolant temp to ecu. If they die the engine overfuels as it thinks it is way to cold.

If you have a scan tool that can connect to the car your should be able to see coolant temp in the live data

 

[Holden439]

Yea I’ve replaced the vacuum line to fuel reg and no fuel in it checked it a couple times. And yea next thing would be to get injectors checked but was running motor before without over fueling. Yes same manifold it’s just standard manifold. Yea read about coolant temp senosor on here if somethings not right will it go that far of fouling plugs straight away? And no scan tool but checked fault codes and only comes up with 12 which is supposed to system good?

 

[WitiTune]

Yeah if engine thinks it is at -40° it will over fuel like hell. If it still has a circuit it may not throw a code. Need to check the live data and see what the temp reading is at to confirm.

Checking injectors is also never a bad idea, had quite a few in recent years with stuck injectors.

 

[BlackVXGTS]

......If they die the engine overfuels as it thinks it is way to cold......

Misleading comment. A failed coolant temp Sender (single wire) will not cause overfueling, but will cause the temperature gauge to be faulty. The comment is correct for the coolant temp Sensor (two wire).