1989 Volvo 240. Last week during a winter storm and driving over bumpy packed ice, I was losing power (misfiring and constant on/off sound of the engine). I had to pump the gas pedal to get anywhere slow. I pulled into a parking lot for the night and got a ride home. The next morning it started fine but I still had it towed to the dealer just in case. They replaced the coil wire, distributor and cap, spark plug wires, spark plugs, and cleaned the throttle body. They didn't see the actual issue but sprayed water on top of the engine and supposedly it stumbled from that.

Today there was another winter storm, I got a mile from work and the same problem was occurring again. I made it to a service station where I was actually able to show the mechanic the issue. He is looking at it tomorrow but off the top of his head he guessed it is either the coil or a fuel issue.

Anything else I should ask him to look at specifically? I don't want parts thrown at this again.

If they are saying it is Fuel Pump, I would think it is only a bad connection to the pump, not a bad pump.
With the basic Electric Tune-Up stuff done,and moisture being the issue... As others have said, Check the Fraying on the Crank Sensor and also look at both the Fuse and Fuse holder on the Drivers Fender well
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Crank Position Sensor

frayed insulation.

Shop just told me it is the external fuel pump. Is it possible for this to be effected by water splashing in the area? I'm not sure I believe it. I suppose it could be a coincidence.

did anyone check the 25Amp fuse that's powers the main pump...it's under the hood on that short rail on the drivers side fender just rear of the battery....follow the smaller red wires that come off the positive terminal

It's a blade type fuse and the contacts can get corrosion on the fuse blades and inside the holder... didn't the dealer check this.

You should take it back to the dealer...because they didn't fix the problem and they KNEW they didn't fix the problem because when they sprayed water on the engine it stumbled......they OWE you...for your breakdown during the next storm....they didn't fix the problem and still sent you on your way.

Did the Dealer check the Crank Position Sensor? and rule that out?

I had a similar problem a year or two ago.

I checked the in tank fuel pump, big fuse, fuel pump relay, and crank position sensor.

My problem ended up being one of the spark plugs. The ceramic had chipped away from the tip of the electrode and it wouldn't run right when cold and upon initial startup.

13

Your post said MISFIRE. and you wrote that the dealer:

"They didn't see the actual issue but sprayed water on top of the engine and supposedly it stumbled from that."

a bad fuel pum would not cause a Misfire and spraying water on the engine....the main fuel pump and fiter are located under the car below the rear seat...

I think the shop is throwing a really expensive part at it...Pump and filter about $200+ plus labor?

Don't do it.

Thanks. Not going to do it and limp it home instead. Supposedly he checked the coil and AMM, okay. Then he checked the fuel flow from the pump and said it is low. He did not measure the voltage at the pump. With moisture, I suspect an electrical issue to the fuel pump or fuel pump relay is likely.

If moisture is a coincidence, would the fuel pump run intermittantly? Bad one day, okay for a week, and bad again 7 days later?

There is a difference between a MISFIRE...which is an spark/electrical problem and Fuel starvation or a no fuel situation.

aka: fuel or spark....you've got to isolate which it is.

the fuel pump running intermit: 25Amp fuse, fuel pump relay, OR damaged wiring at the pump...(tho this last shop you had it at should have seen damaged wiring if they told you that you needed a new pump.)

But usually Fuel Pumps either run or they don't run.

There is another PrePump inside the tank and if this fails, then when the fuel tank is near empty the main pump can't pull the enough fuel out of the tank and you can get a loss of power and stumble...but then if you fill the tankup this condition will go away.

I assumed it was a misfire because it was a consistent stumble. Although low fuel I suppose could also be consistent. I have no doubt now that spark is good.

I just drove it back to work from the shop. It stumbled (low power, pumping the gas peddle) for the first 1/4 mile. Then it ran fine the last mile or so.

In all instances I have had a full tank of gas (because I fill it up before storms).

The fuel pump relay I replaced within the past year because it was old. Purchased new from www.davebarton.com.

I will look at the fuse and wiring next. I also have mini alligator clips to jump the fuel pump relay to see if it makes the stumble go away.

Did you check the CPS

see

http://www.brickboard.com/RWD/volvo/1538857/220/240/260/280/93_240_stumbles_hot_hitting_bumps_crank_position_sensor_fixed.html

his pix of the sensor

http://s1250.photobucket.com/user/rgoeke88/media/IMG_0005.jpg.html?sort=3&o=24

Last I checked several months ago it was intact (unlike that picture). I have a spare brand new one in the back. Is this easy to replace?

Crank position sensor is fully intact with no broken insulation. The 25 amp fuse seemed a little corroded (some white corrosion which could be rubbed off). The connection from the battery looks good as well as after the fuse where the wire enters the bundle.

I haven't checked the wiring at the fuel pump yet, but looking at pictures it looks like it could be very easy for water to splash on the fuel pump while driving.

Of course it didn't start at all today. I jumped fuses 4 and 6 and definitely heard the fuel pump running. Still didn't start. Maybe it's the coil. Maybe some other fuel issue. I don't have means of dealing with it right now, so having it towed to grandfather's garage and he is going to check it out. He knows these cars better than me. He's worked on Volvos his entire life.

First issue is a bad RPM sensor cable. He put a new one in and it now starts. Next he'll be looking at the issue where it runs poorly in wet weather.

That is the CPS(Crank position sensor). Difficulties in wet weather is almost always the failing weatherstrip at the junction of the hood and cowl, allowing water to drip down on/in your rotor cap....

Thanks, I'll look at the weatherstrip when I get the car back.

Another update: The fuse and fuse connections for the car CPU were bad so he replaced them. Not sure where those are located... somewhere in the engine bay?

Near the battery may be mounted on the inner fender or just hanging. Replace the spade fuse holder with a water proof marine fuse holder.
Dan

Didn't realize the 25 amp fuse was for the CPU. It looked good to me but I didn't measure resistance through it to confirm.

Look for corrosion at the blades of the fuse holder and at the + battery connection. $6 -8 replaces it with a nice new waterproof unit.
Dan

Coals to New Castle

or is it "you can lead a horse to water..."

I'd say I was only led half-way to the water!

It's one thing to talk about frayed insulation on the CPS, but I didn't think muck could build up on the part which is supposedly enclosed. No one mentioned that.

And exactly how does one check a fuse other than look for corrosion and continuity? Both of which were good.

Either obtain or fabricate a fuel pressure gauge. I made one of these for my 940 a couple years ago : http://www.brickboard.com/RWD/volvo/1164587/740/760/780/fuel_pressure_gauge_fitting_1990_740_gl_4c_pics.html
Without a gauge...your just guessing.