First off, I was looking through the threads that i posted looking for help in the past and it reminded me to thank everyone for their help. Tech. Pierce. SwiftJustice. Everyone thank you for the help. I have come to love my Volvo's more than any of the cars I have had in the past.

So every now and then for the past few weeks my 85 244 is a bit finicky when trying to restart after maybe a ten minute break or so. Like when i come home for lunch from work. it doesn't ever do it if I turn it off the try to immediately start it. and it doesn't ever do it on the first start of the day.

It will turnover and begin to fire but doesn't start entirely. When I try to start it again it just cranks and cranks with no fire. after a fair bit of cranking with my foot solidly placed on the accelerator it will start and idle badly with black smoke. if i so much as move my foot off the pedal. It will die. If I get it to run in this poor idle for a minute then quickly turn it off with the key the next attempt will usually but not always fire and run fine.

I have noticed a small drop in mileage from the typical 24-27 down to about 21-23.

Unfortunately, when this happens i do not have the time to stop and pull the plugs for the purpose of diagnosing. the most recent tune up in late april included plugs cap and rotor. any ideas would be great.

 

you should never have to step on the gas when you start a fuel injected car. the fact that you do says something is way wrong.

1985, is that LH-II or LH2.2 ? there's some subtle differences and I'm less familiar with the older models. when they are cold, they need to squirt in extra fuel, later model cars (LH2.4) just use the main injectors, while earlier ones had a seperate 5th cold start injector...

there's a ECT, engine coolant temp sensor, that tells the EFI and ICU (ignition control unit) how warm the engine is, so it knows how rich to make the mixture. there's a idle control valve under the intake manifold that modulates how much air gets past the closed throttle, this is only used when the idle switch on the throttle indicates that the throttle is completely closed (zero gas pedal).

my daughter's 87 240 (LH2.2) had a intermittent warm no-start, it turned out to be a dying main fuel pump. worked OK cold, but when warm, it wouldn't start. once it started, it was fine. it only failed when she was elsewhere, I could never get it to fail. eventually it died completely, allowing us to diagnose and repair. this car has 400K miles

 

Thanks Pierce. It is the LH2.2. I'll take your direction toward fuel. I'll go through the Bentley and see if I can narrow it down. Main fuel pump seems plausible as last summer I replaced the transfer pump and not the main. I will post my findings.

 

So I started with checking the main pump. I wouldn't have said that excessive noise was something I was experiencing until hearing the new pump.

Here is what I did:
I ran the pumps by bypassing the terminals at the fuel relay. I could hear the in tank and definitely could hear the main but it didn't seem too loud. There was battery voltage at the main pump terminals. I didn't do a volume test and skipped to the coolant temp sensor.

I pulled the sensor and used water in a glass and a thermometer. I microwaved the water for a minute or so then put the sensor in the glass and measured the temperature and resistance. everything checked out.

I could hear the throttle switch click as described in the Bentley manual. Then I checked resistance at the terminals on the air control valve. it was a bit higher than I would like so I removed the valve and and rotated it back and forth. the piston moved normally.

so.....

I bought and installed a new pump. it seems to have fixed it. I SHOULD HAVE DONE THE PUMP VOLUME TEST. The new Bosch pump is very quiet compared to the aftermarket one that was in there. The whir is much healthier too.

I'll also note that in a past thread of mine I asked about problems that pointed towards a failing transfer pump. I replaced that pump and not the main pump or filter. there was some discussion in that thread about whether or not you should replace both pumps at the same time. I would say that the savings in cash cost now outweighed the inconvenience of doing the work twice.

Thanks again. Pierce for pointing me towards fuel. I was totally headed in the wrong direction thinking it was something to do with ignition when I started this thread.

 

Today at lunch I am back to the same problem. cranks and almost fires but dies. then will crank and crank but no fire unless my foot is buried in the floor. it fires and idles very poorly then i turn it off and it usually fires on the next try. I am going to go through the IAC checks again as well as the coolant temp sensor. wish me luck.

 

i'm wondering if you dont have a problem with the fuel pressure regulator. disconnect the vacuum line off the back of it, is it wet with gas? if so, the FPR is dead and needs replacement.

Another possibility here, since sometimes it seems to run OK, is bad wiring. that can cause all kinds of erratic behavior.

 

You have a bad Fuel Pressure Regulator. Warm start problems, first thing to check.