Terrible misfiring in my 240
 

My car is an 86 Volvo 240. I bought it a month ago and I’ve been trying to get it to run properly. It allegedly has been in someone’s driveway for a year without being driven. The car has around 75,000 actual miles.

The problem is that the car does not have power, it won’t go faster than 35, and it is constantly stalling and surging. When it first starts, it idles well and sounds and smells OK. It will move slowly forward (auto trans) but hesitates for a moment before it accelerates. When I start driving ( the first 10 minutes of driving) I get up to 35 mph and it surges a little so that you can feel that it is not running smoothly.

After it is warmed up, it runs for about 3 seconds then stops as if the ignition has been turned off then it runs for another 3 seconds and stops. This progresses until I am going about 2 mph with my flashers on and a whole stream of traffic behind me. I keep restarting the engine and get another 100 yards from it and it stops again. Today, I drove it to a parts store about 10 miles from home and it took me over an hour to get home. I live in Florida and the weather has been in the 70s all week.

It feels like it could be bad fuel or a bad fuel pump—starved for fuel—but it sometimes backfires when it restarts itself. The backfires are small and not very loud. The car was not run for a year so the fuel could be bad but I have filled the tank twice and the running has not improved. I have added Prestone fuel injection cleaner to both fill ups.

I have put in new spark plugs, new air filter, new oil & filter, new fuel filter, new rotor and distributor cap, new oxygen sensor, new throttle switch, and have cleaned and adjusted the throttle plate.



The only thing that made a noticeable improvement was the new plugs. I did that first and the car ran passably well for a while. Every new addition has made no improvement, it actually runs worse than it did when I got it. I have studied Haynes and Bentley’s manuals and I’m at my wit’s end. What can I do to make this thing run right? I need your help, men.

Fuel may be a suspect... But I'd look at the timing first. Belt missing teeth, harmonic balancer internally separated, etc. These symptoms seem like timing to me...

I would check vacuum line (assuming you haven't) and the Fuel Pressure Regulator. Take off the the vacuum line to it and sniff it. If you smell gas, it leaks and it not regulating fuel properly.

FPR will do this, ask me how I know....

It certainly sounds like a fuel or timing issue or combination of both. The car was sitting for a year, so you drained out the old gas and replaced it with new? How about the fuel strainer in the tank? It is very susceptible to being lacquered up after sitting in bad fuel for a year. There is likely also a tremendous amount of crud built up in the fuel lines themselves that Seafoam will not get out. You may end up changing the lines.

After that, and verifying the timing belt is good and hasn't skipped a tooth, I would start checking sensors that operate with magnetic pickups. The inductive coils tend to fail more as they warm up.

I'm out of town this week so I haven't done anything with my problem car.

Lev, I didn't think about the timing belt. I'll have to check it out.

Titan Joe, I've checked the vacuum lines but I'm going to look at them more closely now. I haven't checked the fuel regulator yet but I will and let you know the results.

Cycleboy: very interesting about the inductive coils going bad when warm. Could you tell me which sensors have them so I can check them out?

Also, I forgot to mention that I also replaced the motor mounts and the ignition coil.
Thanks again for your help here.

Well, I solved the mystery. It was the fuel strainer on the inlet of the in tank fuel pump. I cleaned out as much of the gunk that was in the pump inlet as I could, and installed a new fuel strainer on the inlet.

I started it up and it purred like a kitten. When I reved it, it didn't hesitate like it always did and, it didn't die when I took my foot off of the gas.

I'm one happy guy. And, thanks everyone for your help.

Well done!

i had sameproblem quite a while back. defo the fuel pump.