Hey all, I have a 1994 Volvo 940 n/a b230f, before it died it had a couple weeks of running like **** and stalling at stoplights, weak acceleration, and bogging down, and being hard to start again.
First I thought it was a fuel issue but inspecting the fuel system everything seemed to be in running order, and it wouldn’t even fire on starting fluid.
the entire ignition system is brand new and has spark on all 4 cylinders
so far I’ve replaced, the fuel pump relay, radio noise suppression relay, the crankshaft position sensor, and fixed several broken or frayed grounds for the electrical system

im decently competent with working on stuff but I’ve came to the end on my knowledge, not to mention all my previous vehicles were old carberated ford v8s that are hard to kill and won’t stop running, only other thing I can think of is poor compression, I’m picking up a compression tester later today to test it but I still don’t think that would cause it to not even try to start

 

Have you checked for any codes? Maybe, check the timing belt - a slipped or worn timing belt could be a culprit.

Also, a clogged catalytic converter or exhaust restriction could cause similar symptoms. Have you noticed any unusual exhaust smells or sounds?

Plus, I’d suggest checking vacuum hoses and connections, including the intake manifold gasket. Leaks in these areas can mess up the air/fuel mix, causing rough running and starting problems.

 

I mean it could be an o2 sensor issue but I doubt that would cause an absolute no start, I did a cat delete a while ago so that can’t be clogged, I’m almost certain the motor is in time, I also know the pcv is clogged but yet again I don’t think that would cause a no start, might pull that intake manafold off and see what’s up in there, all vacuumed lines are good

 

you might have a bad MAF sensor, try to swap with a known-good MAF
vacuum leaks and manifold leaks could be a problem, but I have never known an intake manifold gasket to fail in that manner
O2 sensor wouldn't cause a no start, neither would a clogged cat (but it might cause poor performance)