Cranks, Fires, Won't Run Without Throttle

[93tealstang]

Bought an 87 GT and have an issue I cannot pinpoint. Fuel pump will prime, car will crank over and fire but will not stay running on it's own. I can keep it running with throttle applied but when I let off, it dies. Seems normal when revving. Motor sounds good, nothing abnormal, simply just won't stay running. Checked fuel pump relay, idle air, mass air meter, MAP sensor, spark plugs, replaced ignition switch since it was seperating and replaced fuel filter. Car will run and drive pretty much except when no throttle is applied. Very gassy smelling when it does run.

 

[FRANKENSTANGNET]

I have the same problem with my 93 GT. It would be nice to figure this one out

 

[jrichker]

You said Mass Air Meter - that means the car was a Mass Air conversion, unless it is a California car. Recheck the Mass Air conversion work for broken wires or vacuum lines. MASS air conversion instructions from http://www.stangnet.com/tech/maf/massairconversion.html for more help. Make sure the MAP/Baro sensor vents to open air and is not connected to vacuum. The sensor is the same internal part, but speed density MAP is connected to vacuum and Mass Air Baro vents to open air, no hose or lines of any kind attached to the sensor.

If that was all good, here's your next step...
See the "Surging Idle Checklist” for help with all your idle/stall problems. You can guess at the problem and throw parts at it, or you can use the checklist to help you find the problem quickly and inexpensively. The checklist is right here in the Stangnet 5.0 Tech forum and you don’t have navigate to some other unknown web site. It‘s free and doesn’t cost anything: at last count there were more than 103,000 visits and still climbing

The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the fixes & updates. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.