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K-car runs very rough and soon stalls

My 1989 Plymouth Reliant with 170K miles was running great until yesterday. Then, when I started it, it ran very rough and soon stalled. Couldn’t restart it until it cooled and it soon stalled again.

Diagnostics already performed: Valve timing checks OK. Spark plugs have spark. Electrical timing when cranking cold is 4 degrees BTC. Fuel is reaching the throttle body injector. Compression is 150 psi in all cylinders with engine cold, all plugs removed, and throttle open. I haven’t detected a vacuum leak, but haven’t systematically plugged each nipple on TBI. Air filter is new. No trouble codes in computer; just 12-34-55 which is normal. Cams and rockers look good; adjusters all firm.

Possible clues: 1. Valve cover has two nipples. One is for PCV. The other should be for input, but it is blowing out. 2. When engine runs, I thought I felt exhaust gas flowing parallel to cat converter. But no sign of hole in converter or upstream exhaust manifold that I could see. Might there be a classic exhaust system blockage of which I should be aware?

You have one of the most disposable cars on the road or off it. Disposal is the most sensible plan.

Look at the vacuum diagram to determine where the second port on the valve cover goes. Click on this site link, and scroll way down to Fig.33 thru Fig.37. Choose the vacuum diagram for your engine. Click on that image to enlarge it. Click on the maximize symbol to enlarge again.
To determine if the problem is lack of fuel, spray Starting Fluid into the air intake tube. Try to start it. If it starts, and runs a few seconds, there is a problem with the fuel injector opening.

Ah, come on now. Anyone who’s gotten one of these things to stay on the road this long and for that many miles obviously loves the thing and deserves some kind of constructive advice.

Post your question here. You will get a lot of help from fellow K car owners.

I saw this on a Plymouth Caravelle, probably the same engine. The vacuum line to the Manifold Pressure Sensor had broken broke. It was not obvious because the plastic part of the line snakes under the manifold. When I disconnected it from the sensor and pulled on it, the broken half just came out. A couple of bucks for plastic tube and rubber hose fixed the problem.

I was able to get the codes out of the computer by cycling the ignition key ‘on’, ‘off’, ‘on’, ‘off’, ‘on’, ‘off’ then ‘on’ and the CEL flashed the error codes. The error code I got from the Caravelle referenced the MAP sensor so I looked for the obvious there. Luckily it wasn’t the sensor itself.

Hope that helps.

I 2nd starting fluid.

Do you hear the fuel pump prime when you turn the key?