84 240 DL running rough

This is my first Volvo experience, so I am a little puzzled.
We bought this vehicle from a friend who let it sit for a
few years. Put it on the road and it seemed to run fine.
Over a few days it started running poorly, bad idle and
backfires under a load, but runs alright once you get up in
the RPMs. I have checked the fuel filter, its fine. Almost
seems as if it is starved for fuel. Any leads?
jd

 

A sitting car (particularly one that saty for years) that ran fine at
first then rough after some time points to a vacuum leak. Seals and
hoses were fine at first but the heat and vibration of the motor can
crack and loosen them. When it is running you may even be able to hear
a hissing and trace it down, but you can spray WD-40 around the intake
manifold for a sart and see if the idle changes. it could even be a
vacuum line under the dash somewhere as well (they are used to control
the ducting of air for the heater/air conditioner).

Basically, start with all the hoses from the air cleaner all the way
to the head, and then go from there.




__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

 

Perhaps water in the gas?
Drive to a gas station, and put in 2 bottles of dry gas, or even 90% rubbing
alcohol and then about 1/2-3/4 a tank of gas.
Let the tank run most of the way down, then do it again with a full tank.

Best luck!

 

Or maybe just old gas?

While we are on this project... Alcohol in gas can be a problem in
stored vehicles. The alcohol grabs water and water vapor and then is
it heavier than the gas. It settles on the bottom of the tank which
can, over time, cause rust. When the vehicle is first started this
water-laden alcohol is drawn into the system since the pick-up is at
the bottom of the tank. In motorcycles it is particularly a problem
because of the way the reserve setting on the petcocks works. When at
speed, if the bike is switched to "reserve" a sudden rush of water can
be drawn into the motor.

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

 

I had an old Saab 900 that suffered similar symptoms. I got the car after
it had been parked for most of a year. Turned out that rodents had built a
nest in the exhaust system somewhere. The car ran fine at first, but the
nest eventually dislodged and nearly completely blocked the exit of exhaust
gases. It finally blew out in a huge puff of smoke and debris.

--Dale

 

I join in the "bad gas" chorus. Really, the best approach from the car's
point of view is to drain the tank and put fresh gas in it, along with some
injector cleaner. But then you have some other container full of gasoline
that you can't use.

You can see if injector cleaner helps. (It's cheap and simple.) Since the
problem slowly developed it sounds like the injectors are slowly getting
gummed up.

Mike