please please help

i have a 84 c4  that will not restart after sitting for 5 minutes. if i stray starter in it off it goes with no problem   I have replaced the fuel pump and have recently installed a check valve on the fuel line still no go .  looking for any help before i make next move    thanks  

have you changed the engine coolant temp sensor????   its on the front of the intake manifold.. usually with a black and yellow wire on it.. the crossfire cars usually have a coaxial type of connector..   if you have NOT upgraded to the newer style.. you should do this next...    SU102  at autozone. is the engine temp sensor and the replacement pigtail.



when the coolant temp sensor fails..  you will have a warm to hot NO start without extra fuel as the system

you can see the coolant temp sensor.. under the smog pump on the Front of the intake manifold...



what it does is the computer sends 5 volts to the sensor.. there is a variable resistor that changes resistance with temp.. so there is a variable voltage back to the ECM on the other wire..   if this sensor is bad.. or the connector is bad.. both happen..  the computer won't know what the actual engine temp is so it won't spray the proper amount of fuel in..



A few things...   have your changed the Fuel pump relay on the firewall.. between the power brake booster and the distributer..??/








the fuel pump relay is item 5 on this map...



next... sort of under the distributer.. you will have either ONE or TWO oil pressure switches depending on the date of production...

if you have a switch with 3 wires on it...     the outer two terminals also run  the fuel pump when the oil pressure is UP..  the center terminal is for the dash board gauge...



if you have a single wire oil pressure switch.. you may have a 2 wire switch like this in there also...   this is the fuel pump oil pressure switch.. it closes when you have enough oil pressure



the oil pressure switches are probably working..  as you say it will start and  run when you give it a shot of spray...  so i would really look at the fuel pump relay..



another thing to check is the ignition switch... these are mounted on the top of the column and a Pain to change...   might take an hour on that car..



why am i worried.. this is the inside of the non tilt column ignition switch..



notice the dent in the contact rail???? making contact intermittent..


you have to understand.. that on this model.. when you turn the key to the run position.. the fuel pump should turn on for two seconds..

the fuel pump should come on again while cranking....  

then continue to run when the engine is on...

the computer also needs signals that you are cranking the engine..  with a scan tool you can see if the ignition system is getting a cranking signal...


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you might want to click the view Active posts link...   somewhere .. usually on the first or second page is a post i put up on scan tools for the C4 corvettes...


OH>...

the SU102 coolant temp sensor and pigtail are under 20 bucks at most autozones... special order in some...

all of them will have the sensor without the pigtail..  

kenyes1 welcome aboard:

The coolant sensor is where I would go first also. When you install the coolant sensor make sure the sensor has a good ground  to the ECM. Put an ohm meter at the base of the coolant sensor and go to the ground of the ECM.It should be infinite. Good luck.
Bob  

I CANT THANK ALL OF YOU ENOUGH I CHANGED THE SENSOR THIS WEEKEND AND THE CAR STARTED UP AFTER A FEW CRANKS. I HOPE ITS  THE ANSWER, IN ANY CASE IT IS A GREAT COMFORT TO KNOW THAT IF ANY PROBLEM ARISES I CAN COME TO GUYS LIKE YOU FOR ANSWERS   THANKS AGAIN