engine dies upon acceleration 0 suggestions?

[vvurdsmyth]

'86 M20- cold start- fine, but when warmed the engine dies when clutch is let out in gear; it idles rough but if it doesn't stall, can be sometimes be teased to reving in neutral; when the revs are high enough slipping the clutch can get it moving and keeping the revs high (running in the lower gears) it seems normal, stopping at a light I have to play with it again to get it moving; when idling often it will die or nearly die when the accelerator is pressed; often when I get it moving by slipping the clutch it will accelerate, then die.

It has a new AFM, new throttle position sensor, new temp sensors; new spark coil, ignition wires are fine; just checked the cold start valve hot, it's tight; the vacuum line to the fuel regulator is fine; there seems no diagnostic check list in Bently's..

.. any suggestions..?

[dnguyen1963]

Classic problems for vacuum leaks. Have a smoke test done.

[vvurdsmyth]

thank you, dnguyen1963

a good suggestion, and I will check that out just to make sure.. I call it the 'suck a hose' test, but I am quite sure that is not it; most hoses & gaskets are new, and this happened suddenly, one day fine, the next day, I'm limping home..

[jlevie]

Get a smoke test done. That is the only sure way to find intake leaks.

[vvurdsmyth]

Thank you all...but it does seem to be the fuel pressure regulator; just as an experiment, this morning I shot a spritz of silicone lubricant into the vacuum side of the regulator, reconnected the hose and gave it a few hard sucks, started it and let it warm up reving it a bit; drove it around the neighborhood... it's fine, but it being 28 years old, I will order a new regulator. Thank you again.

[jd_e30]

Do a fuel pressure test before you start spending too much money on parts. You can easily test for a bad fpr, leaky injectors or a bad fuel pump check valve. If the car starts easily, then it's likely not a bad fpr... But you can do an fpr flow test to confirm, assuming the fpr is holding pressure, though again, a faulty fpr probably wouldn't hold pressure, which would lead to hard starts the longer the car sits.