80 spider running rough

[tuman]

NEED HELP. 80 fuel injection spider that is just running rough. It had previously done this over the past 2 years a few times going down the road it would loose power and sputter, but would simply go away after a few seconds, or stopping and restarting the engine. Now it won't go away. Checked spark plugs, this time one was shot. Replaced all spark plugs, still rough. Ignition problems? Injection problems?

[bradartigue]

First off just make sure you don't have air leaks anywhere in the fuel injection plumbing. Old or cracked air lines, a loose hose, all cause serious problems. If you're confident of no air leaks and you know you are getting fuel (as in, it runs)...

Before you delve into the fuel injection system you need to determine the condition of the ignition system. Test the coil per the shop manual. From there, old or worn parts need to be replaced. Plugs, wires, cap, rotor. Check inside the distributor cap the condition of the two small wires that run to the ignition pickup, if they are bad or old and hard then replace the pickup assembly and control module. Parts that are not old or worn should be tested per the shop manual. Ignition stuff is cheap, so if you're spending time testing 10+ year old parts then consider the futility vs. the $100 or so you'll spend in known good parts.

Once sorted you need to do some testing to determine if the FI system is correct. The entire diagnostic procedure isn't hard to follow if you have a decent multimeter. Report back on the ignition components first.

[GeorgeT]

Replace the fuel filter; this sounds like this could be a fuel flow issue.

[81SPIDERMATT]

I will throw out sensor at the coolant tee ...loose or bad wiring or connections at that location will cause your stumble ..

[majicwrench]

THe key phrase is "One (spark plug) was shot"

What was shot about it?? Is it "shot" again?? Fouled?? Damaged?? Have you fixed whatever "shot" the plug in the first place?? To heck with all the testing of sensors etc what a waste of time. Fix your problem. Fuel filter did NOT damage plug. Have yo checked compression??
Keith

[TX82FIAT]

Great point. you have a know issue with a shot plug. It only takes a few minutes to pull the new plug out and inspect it. The fact that it stumbled previously makes me think it was a small issue that has grown into a larger issue. It very well could be somthing with any one of those parts including the popular temp sensor. However, you know you had a shot spark plug... what caused it!