i have a 93 850 with 205,000 miles. runs great but I have a problem now. Just recently purchased, so I don't have a lot of history. The car starts fine when cold and runs perfectly. When I shut it off (and it is at operating temp) and try to restart after a few minutes, it will crank and attempt to turn over but then go just to cranking no matter how much I use the gas pedal. After it cools down, the car starts easily and runs fine. AAA came to tow the car before it restarted and banged on the fuel pump and filter with no results. But the cool down time worked. I am a first time Volvo owner, so I am not familiar with many of the unique sensors so my first thought is the fuel pump is bad. But reading other threads there may be other things to look for. What do you all think? Thanks

 

Hi and welcome to the site.

Cranking and turning is the same thing. It sounds like the fuel mix may not be correct when it tries to start warm. Does the car have a CEL? You can read the codes with the little boxes near the window washer fluid fill tank.

My guess would be the coolant temp sensor but other's may have other opinions. If you have not owned the car long, you should read the New 850 Owner thread.

 

If you have a check engine light (CEL) that would be really helpful. One thing to do is to check if you have spark next time it's hot and will not start. Since it cranks over you can pull the coil wire and see if you get a spark to ground. That way if there is spark you know you have a fuel issue and if not it's ignition.

 

I do have spark and there is no the is no cel. in my limited automotive knowledge, a bad fuel pump won't trip a light, so that is my thought process. I have read many threads talking about relay but no threads that deal with a hot start problem only. I can go out right now and the car will start and I could drive it 60 miles, but I had better not turn it off unless I want to wait an hour till it cools down.

 

Almost sounds like old fashioned vapor lock. Vapor lock occurs when fuel that is supposed to be in liquid form instead turns to vapor. This can happen as a result of heat soak, or when heat builds up in the engine compartment with the vehicle off.

To start with, I would make sure the previous owner did not move or re-route any of the fuel lines or fuel filter close to a high heat source on the engine (changing the fuel filter probably wouldn't hurt either if it is unknown when it was last changed)

 

When it cranks and does not start, have you pulled a plug to see if it was gas fouled?

My first thought was the coolant temp sensor, like RSPI said. If the sensor is reporting a much colder coolant temp than actually exists, then the ECU will send too much fuel for startup and flood the plugs.

If you had a way to read the live data from the OBDII port, you could know for sure.

 

I have no way to read the OBD. I took it out tonight and got it really warm and the same symptoms. I checked the spark at the coil and plug, plenty of spark ( and a shocking experience for me too). Reading all the threads about the fuel relay, I went ahead and ordered a new one. I am going to pull the plugs tomorrow and see what they look like. Temp sensor?? I thought they were for cold starts only. Where is is located and can i test it? Thanks for all the suggestions. BTW, the dreaded up orange arrow reared its ugly head tonight. First time for this. PNP???? The car runs and shifts perfectly even with the flashing arrow.

 

Flashing orage arrow is the "limp home mode". Could be missing or anything to cause that.

You can learn how to check your ecu codes here:
http://www.matthewsvolvosite.com/read-codes-volvo-850

https://volvoforums.com/forum/volvo-...odes-dtc-9856/

The OBD-I box:
https://volvoforums.com/forum/volvo-...-models-36251/

 

same problem with my 95, replaced coolant temp sensor and thermostat...problem went away. not saying its your problem but its food for thought. also had a 240 with a fuel pump relay acting up and getting hot causing it to stall and not start. i took the cover off and plugged it back in to visually see what was going on, you can engage and disengage by hand to diagnose.

 

pulled the plugs and re-gapped them. they were at 35 instead of 28. I found a hose from the canister back to the tank was disconnected and I spliced in a new hose to reconnect it. took the car out for a one hour drive, ran better than ever and started right up after a 10 minute wait. We'll see.... keep your fingers crossed and say a prayer if that is your choice (it's mine) and I will keep you posted. Thanks again for your help....it definitely is giving me direction.

 

I have this problem as well. So, I guess its the coolant temp sensor acting up? How can I replace that?

 

It's located just under the upper hose and thermostat housing.

 

We had exact same issue. Done the plugs, coils, pigtails, coolant sensor...fuel filter, thermostat. going to chase the hose you mentioned next 😅
Fun stuff!