car will fire but will not staying running? any ideas

the 302 will fire right up but will not stay running after initial fire up...i swapped out carbs and checked the timing but still nothing. It has gas and the carb is getting gas for sure...any help would be greatly appreciated
bob

 

Does it act like you just shut it off when the switch goes back to run? If so check the way the switch is wired. ( happens more often than you would believe)

If it runs for a little while a dies out gradually probably a fuel problem.

 

are you saying that it only runs when you are actually cranking it over with the starter , and when you quit cranking it dies? if that's the case it may not be wired right

 

Does this car have a ballast resistor to the coil? I've had similar problems on SBC when the resistor was bad. It also burnt points terribly then too.
Ol Blue

 

no it fires up when turning the key and will run for a second or two without cranking but then will die out...almost like it was starved of gas but i know its getting fuel ???

 

how about some history of the car? was it working fine, and just started doing this? or is it a new build? or did you change something on it? or what?

might want to pull a plug wire, put it on another plug with the shell grounded and positioned so you can see it, and look to see if spark goes away when it quits.

 

you are sure the fuel filters are clean? also, maybe theres a clog in the line. try gravity feeding it(after checking the carb filter if it has one)

 

OEM or replacement ignition wiring?

Many ignition systems use different logics when starting than running. They will start on one circuit and then swith to another when running. Check the wiring digram and check voltages. I would say the Ol Blue has your problem.

 

Give it a shot of starting fluid and see if it wants to run. If it does you have a fuel problem. If not it is the ignition like coil, or ignition switch

 

this is the second motor in this car the first 302 started knocking really bad, that one would run and idle fine but when i swapped this one in and hooked it up (exact same way the first one was) it will only fire up and then die out...the only difference in the two motors was the first motor had smaller spark plugs then this motor...could that have anything to do with it?

 

if you can keep it running with the throttle I would expect to find plugged idle circuits, a vacuum leak, or possibly a plugged bowl vent. You might want to put a test light on the coil just to verify that you are not losing voltage to the coil after it starts. Ideally you would have 12 volts to the coil when the key is in the start position and about 8 volts to the coil (give or take) when the key is in the run position.

 

Had a similar problem once, not enough fuel pressure. Mine was a clogged screen in the gas tank. Fuel pump could not hold enough pressure to feed the carb. You may try blowing the fuel line back to the tank (take gas cap off first)

 

Did you put the old carb and distributor and coil from the old engine onto the new engine, or are they the ones that were on it?

 

Try to keep it running with a can of starting fluid and the hood up, if it stays running its fuel

 

i just swapped everything from the first motor onto this motor except intake manifold

 

oh i have an electronic fuel pump

 

The quick check for the ignition would be to run a wire from the battery + to the + side of the coil as a jumper. If it keeps running, then you know it's a switch or wiring issue. If it doesn't then look at fuel. Just don't leave the wire hooked up for more than a few seconds before or after trying to start or you could fry the points or electronic ignition, whichever you have.

 

Duraspark ignition?

 

motocraft-standard ford
i just went to start it up and when it died out i had a nice little fire in my carb...is it a timing issue, usually fire in the carb indicates timing, right?

 

Yep, put some advance in that ****er

 

could that be why its dying

 

I had the same problem

Check all of your vacuum connections to make sure everything is tight and not kinked. After, check the torque on your manifold and carb bolts. If you checked everything else I'm sure it's a vacuum leak somewhere. Mine would fire right up then die after 3 seconds like it didn't have any fuel. I found this out after going through the carbs 3 times ..on a 3-2 set up...ugh..

I bet that's what it is

 

thanks everyone for the help, i appreciate...i might miss the last cruise in of the season but hopefully i'll at least be cruisin' by the end of the season lol

 

If it's a Ford electronic ignition, motorcraft Duraspark, there are two wires into the car harness, a white, and a red. Switch the wires and try it again.

 

Is the electric fuel pump wired thru an oil pressure switch? Is it wired correctly? If the engine isn't making sufficient oil pressure in a few seconds it may be opening the circuit to the fuel pump. When you were swapping things around, did you get all the ground straps reconnected? Just grabbin' at straws here. Good luck!

 

Got that shirt last week

 

wtf!!! does this have anything to do with this thread?

 

Is the distributor 180 degrees out? Or is the timing chain on the replacement engine worn and jumped a cog or two? I chased a problem similar to this for some time and found that the timing chain had jumped. It would pop back through the carb and did begin flaming away once.

 

see i was thinking maybe timing as well, but it wont run at all if the timing is 180 out right? How do you check for the timing chain wear?

 

turn the crankshaft clockwise just until the distributor rotor moves, then turn the crankshaft counter clockwise until the rotor moves the other direction. If the crank turns more than about 10 degrees the timing chain and sprockets are suspect.