1995 Volvo 850-Won't Start Warm + Stalls after Long Idles

[ThekurgansheaD]

Hey Guys,

I have read several threads describing similar no start conditions but many of them terminate without the OP sharing a conclusive resolution. Makes me wonder if this is a popular 850 killer. The car will not start when the engine is warmed up, but reliably starts perfectly when the engine is cold. It will also potentially stall if you apply the throttle after it has been idling for an extended period.

This was my daily driver for many years. I got a new truck and loaned the car out to a friend that was on hard times. When I got the car back, it needed new strut tops, so I let it sit for couple months without regular driving before I could get around to fixing these. When I got the car back on the road, it began experiencing an intermittent failure to start after the warm engine had been off for a few minutes, like when refueling or running inside a convenience store. This problem got progressively more prevalent until it was the new norm.

{In pursuit of a resolution, I have since replaced;

Fuel Pump and Fuel injector Relays
Thermostat and ECT Sensor

When these failed to produce a fix, I took it to my mechanic who works on all brands and consults another local mechanic for imports. They replaced:

CPS, Ignition Coil and Wires

This didn't work. }

Typically the car will not start until the engine has sat for at least 1-2 hours and the engine has completely cooled, however I have gotten the engine to start in a pinch immediately using two different methods.

1.) Pulling the fuel pump fuse and cranking for a few seconds.
2.) Trying to start with the Airbox open.

^this makes me think thats its flooding/fuel related.

I want to also mention that I discovered that the air box thermostat was dysfunctional and just pumping hot ass air into the intake, so I have since replaced the thermostat with a small socket so the flap stays open to the correct side and deleted the hot air hose from the system. I was hopeful this would fix the issue but it did not. I'm wondering if too much hot air could have damaged the MAF, but the typical trick of unplugging MAF doesn't seem to resolve anything and the car won't start or run at al with the MAF unplugged.

PVS seems good. Passes a glove test. IDK why that would matter in this case, but I thought I would brag about something.

Again, I know these symptoms have been addressed but most of the threads accuse the parts that I have already replaced and many of the OPS never share a resolution.

Thanks,

Luke

[abscate]

These are modern cars with respect to engine management and rarely diagnose by symptom - aka My car does this, what part did you replace?

You have to start with the maintenance history - has the car been kept up with required stuff or are you running it all on marginal parts?

New aftermarket parts, often used by non-Volvo mechanics, can be worse than old Volvo parts.

A quick way to diagnose the fuel vs ignition troubleshooting 'fork' is a shot of ether. If ignition is even marginally present, the car will light off and run for a few seconds on ether.

[abscate]

Thermostat and ECT Sensor

What brand did you use? The aftermarkets here are known to cause problems. The connector to the ECT sensor is also weak until the 1999 model year

[ThekurgansheaD]

abscate-I should have mentioned that I don't have a CEL and My car is pre-OBD Port.

I used a FACET brand ECT that I ordered from FCP, so not OEM.

[ThekurgansheaD]

You have to start with the maintenance history - has the car been kept up with required stuff or are you running it all on marginal parts?

[quote/]

I have kept up fairly well with maintenance. Ive replaced cap+rotor+plugs+ cables + fuel pump+ filters + timing belt + water pump all in the last few years.