Lennyseleven

Last week I was having a problem with my 90 Carb'd Mustang, where it ran like crap, died and wouldnt start again. So yesterday I got it started and it would idle but it has a miss. I think one of the plug wires is loose so I pulled it off the plug while it was running to see if it got worse or not.
and it abruptly just quit. What does this mean? Shouldnt it be able to run on 7 cylinders?

thanks
Nick

mdvaldosta

the purpose of pulling a wire (really should have grounded it instead, its easier on the coil) is to check for a dead cylinder. The idea is if you ground out the cylinder and it doesnt run any worse, than that cylinder isnt hitting. Have you changed the plugs, wires, cap, and rotor lately?

Lennyseleven

I know, so why did it completely stop running?
The plugs dont look bad but it wouldnt hurt to replace them, this engine was built before I bought the car, so could I take a plug with me to the parts store to get the correct ones?

Today it ran for a minute and then stopped and i noticed the clear fuel filter is empty.
I believe it has a mechanical fuel pump(above the oil filter?).
Would a weak fuel pump make it run like it was missing?

thanks
Nick

VertStangGT86

Shouldn't have stopped unless there's other problems and that cylinder was keeping it alive. Take an old plug with you and see if it matches the ones for your year. They may have done a car conversion and go from there. I'd go through the whole thing while you're at it if you've got the moeny; dist cap and rotor, maybe new dist as recomended above, plugs, wires, fuel filter, oil/filter, ummm having a mind fart so if I forgot anyting just add it.

Lennyseleven

Is there any way for me to test the fuel pump?
How do mechanical pumps actually work?

thanks
Nick

mdvaldosta

you can check fuel pressure from the pump with a gauge, carb'd engines usually run 6-7 lbs to the carb. mechanical fuel pumps are bolted to the engine and are ran by the camshaft. The pump has a lever that rides along a lobe on the camshaft, causing the lever to move up and down pumping fuel through the pump

Lennyseleven

So how does it pump fuel to the carb before the engine running?

Nick

roundman

it doesn't, but the fuel bowl in the carb holds enough fuel to get the motor running and the pump starts pumping as soon as the starter starts turning the motor over. if there is no fuel in the filter you can see, and it doesn't fill up when you crank the starter, then the pump is probably bad and needs to be replaced. or you could get a block off plate for the hole in the block and install an electric fuel pump instead of the mechanical one.