1998 Volvo S70 engine trouble

When it doesn't start, are you getting spark and fuel to the engine? Was the check engine light on? Will it start with starting fluid when this happens?

Hi:
You replied, but there is nothing written.

It restarts sometimes if you feather gas,but it acts like its flooded,have to play with gas,brake torque it to keep it running.Smell of gas is heavy,lots of smoke,can't drive it.Have to keep it revved way up to keep it running.As I said,let it cool off 2 or 3 hours and it will start and run smooth again for another 5 minutes or so,till it gets hot,then dies like you shut the key off,then same thing,won't start.You see what all I replaced,what else could make it shut off when it gets warm.

You provided more info this time. Tell me, is the smoke black from the exhaust? If it is, check to make sure the fuel pressure regulator is working and not allowing too much pressure to build or sucking fuel through the vacuum supply. If that is good and pressure is within the manufacturer's specs, I really need to know if there is spark to the plugs when it doesn't start. If there is, I would suspect an issue with the coolant temp sensor or the PCM itself.

Let me know what you find and if you have access to a real time scanner.

How can I test the coolant temp sensor?What is the PCM,and how can I test it?I have fire to the plugs,it restarts sometimes,have to feather the gas pedal,when it does start,it blows black smoke and misses until you get the r.p.m.s up.If you keep the rpms up and don't put it in gear,it will run for a while.As soon as you try to let it idle,it dies,or if you put it into gear without power braking it,it dies.When it very first started messing up,right before it would die,it smelled like catalytic converter was stopping up,and the smell of gas also.I have no access to the scanner you are talking about.What does or is the scanner gonna tell me,or do also?

The scanned will identify if there are trouble codes, and you can see what kind of signal is being sent by the sensors to determine if they are working properly.

Based on what you mentioned this time, have you checked fuel pump pressure? You may have a bad pressure regulator allowing too much fuel to enter the engine.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If it had a bad fuel pressure regulator how could it start and run so good until it warmed up?

I found there was no vacum going to the fuel pressure regulator.Checked the vacum line all the way to vacum canister.Its ok.No leaks.

Can I run a line from the manifold straight to the fuel pressure regulator with out damaging it?I bypassed the vapor canister purge sylonoid and ran it straight to the vacum canister,It had vacum to fuel pressure regulator then,it ran great for just a minute,then died.Will not start back now even when cold.Hope I did not damage the fuel pressure regulator already.The vapor canister purge sylonoid had vacum to it,but was not passing through it.Not sure just how the purge valve is supposed to operate.Noticed it had a couple wires running from the top of the fan shroud to it.Must be gettin 12 volts from some kind of sensor.Please answer questions in simple form,Lots of abbreviations I do not understand.Thanks,Chris.

I have been using all your input to track problem.Its been a great help. Hope you answer above few questions.Getting ij to finding main problem.please answer

When trying to start it now, do you smell fuel? Also, have you checked fuel pump pressure with a gauge?

No i did not smell fuel.i had not checked fuel pressure because i found there was no vacum to fuel pump regulator.vacum lines were ok no leaks.