Wont start spark but wont run

What is missing from the firing;
Air, Fuel, Compression and spark.

Check for spark.. pull one spark plug out set it on bare metal(away from cyl hole fuel could light from spark) turn vehicle over and look for spark should be a nice lightning bolt looking spark... blue spark is weak spark.. and see if it's getting spark...,, if not,,."try new plugs.,wires,distributor cap&rotor " also first.spray a little starting fluid down the injection system turn it over and see if it fires.if it does then it's a fuel issue prob not electrical... try that.hope it helps

If you have spark and compression and it not firing then you must not have fuel. the fuel is fed from the demand regulator thru the intake independent for each cylinder. Check the intake and make sure that the NG/LP pin is all the way to the NG side.

First you must determine if the fuel is stopping or the spark is stopping..If the fuel is stopping this could be a computer problem.. If the spark is stopping then it could be the IGN Module in the distributer. or any nomber of sensors. Squirt a little fuel directly into the Throttle body on the intake manifold.. If the truck runs longer its probably loss of fuel.. Do this several times to make sure, be careful and only use a small amounty of fuel.. you do not want a fire.. RE: Spark: Take a plug wire and an old plug..put the wire on the plug.. hold the plug against a good ground .. have someone crank the engine .. does the plug stop firing? The engine dies.. and will not restart for a minuet or so.. during this "no start" time do the plug test. If the plug will not fire during this time take the module out and take it to Orillys Auto parts.. They can test it.. really expensive part. Don't replace until you know it is BAD..

Are you referring to the fuel lines and if so did you get them mixed up and hooked on the wrong carb inlet? If so try reversing them and see if it starts.

OTHER THAN A MECHANICAL PROBLEM THERE ARE 2 THINGS THAT KEEP YOUR CAR FROM RUNNING, 1 No Spark, 2 No fuel. To check fuel open the air intake and squirt a little fuel into the air intake if the car starts or at least fires you probably have a loss of fuel.. The spark problem, You need to find out if the spark plugs are firing.. if they are not firing the car will not start.. THEN YOU MUST FIND OUT WHY THERE IS NO FUEL OR NO SPARK, BUT FIRST Isolate the system THAT IS NOT functioning.

Could be a relay or other electrical issue.
You say it has fuel pressure and spark, if that were true it should run.
So it either does not have enough spark to fire the plugs under compression, or not enough fuel pressure going thru the injectors, or not at the right time.
You might want to check for trouble codes in the computer.
There has to be something missing from the equation when it won't start. You may have to check all of the plugs for fire and try some carb cleaner sprayed into the intake to boost fuel supply to find the issue.

there are a few things that would cause that wo all i can tell u from what u said is that u need to check for fuel pressure w/ a gauge then look up the specs online. if u lose pressure after start up the fuel pump is bad. but if it stays good as the truck dies then u do have other issues that someone would have to look it over. u could have a ignition module heating up and opening the circuit or an electronic coolant temperature sensor reading -40 or 300 starving or flooding the engine with fuel pull out a spark plug and ground the threads onto something. and check for spark as it dies. if it stops sparking then u need to look into the ignition system. if it does not then you are looking at a fuel problem or a cam positing sensor. which could shut off fuel injector pulse and ignition fire. like i said alot of componets could cause irratic behavior like this ull just have to start off with the basics fuel and fire before you can jump to any conclusions. oh and fuel filters would cause the engine to run bad but not kill it all at once and keep it from starting. one way to rule that out is to turn the key one for 2 secs then off for 6 secs and repeat a few times this turns on the fuel pump for priming iu the system. if it still does not fire up then somethin else is going on other than the fuel filter.

first of all its not good to spray starting fluid into the intake,its got a plastic "LOWER"intake and it can blow apart and **** too much air through it.Next reset the computer and it can be done by un-hooking the battery cable for a few minutes and if this works and runs for a while and does this again,then reset the computer again.If it does it again then maybe replace the computer..Then also check the fuel pump,it may sound like its working but it could have gotten hot and the plastic gear on the end may not be pushing fuel through when it runs for a while.