Well its been one hell of a ride on this one. Reading some posts that are similar but not exactly.

All plugs, wires, cap, rotor replaced in January. Throttle body and MAF cleaned as well. All parts from IPD - I live in Portland.

Not sure if these had anything to do with my problems now but just wanted to point out. Installed IPD sport exhaust after which the car idle went down to about 500-600 RPM - noticeably low.

Dead battery in the driveway. Removed, tested cleaned up the alternator connections after a poor charging issues. Installed a heavy duty ground wire to the block from alternator. I think the ground wire was heavily soiled and look like it was scorched.

All went fine for 2 days then ..

The following day my son runs the 240 low on fuel (yes again) and he says the car begins to run poor then he added some gas. He got the car home and it had very low and poor idle. I drove it the next day and it drove fine until coming to an idle then stall out if great than 5 or so seconds.

1st task - replaced fuel filter

Car became worse after I installed the fuel filter. I did the fuse 6 to fuse 4 to test the inline and intake fuel filters. I can hear both pumps but noticed I had gas leaking out of the brass washer on the inline filter. The inline fuel pump sounds a little buzzy when doing the fuse trick so I decided to pickup a spare fuel pump from wrecking yard. Cleaned up the used pump and installed it. I only hear the pump go on if I over ride with connecting fuse 6 to left side of fuse 4. I dont hear the inline pump when turn the key to start position 2. I also switched out the fuel pump relay with my spare - no change.

I do get fuel to the injector rail both in and on the return line. No fuel coming out of the vacuum hose to the intake. Its smells a little like fuel but not wet or does any gas come out of the fuel regulator.

I did run the codes and I got a 2-1-3 Throttle Switch Full load setting Faulty or ground short. Could this make a no start?

Did spark test on all four plugs - check!

Pulled cover off Timing Belt to check it was intact and attached when spinning crankshaft - check!

Removed MAF sensor - no difference

I pulled the spark plugs. Very black with carbon and smelled of fuel. I cleaned them up then reinstalled. The 240 started! Very rough idle for about 10 seconds then stalled out with poor idle. After doing this a few times the car is back to not starting. I'm probably fouling the plugs with fuel?

My son says he has been getting very poor gas mileage but hard to say if that is a fact or not. After looking at the plugs maybe that is possible.

I know that is a ton but I'm running out of ideas. I'm thinking of going to the junkyard and getting a fuel pressure regulator and the coolant sensor but not sure if either of those are my issue. However, I dont want to just start doing the replace game either.

Ideas? I think its time for a Volvo Mechanic but if I am missing something please let me know.

 

Called a mechanic and he is suggesting Fuel Pressure Regulator. Went to the wrecking yard this morning and pulled one off a 1990 for $8. I also stopped by Autozone and purchased a fresh set of Bosch Super Plus coppers.

I will update.

 

Removed old plugs from head and ground them. Removed fuse #4. Cranked over motor about 5 times blowing out the fuel. Installed new plugs. Installed fuel pressure regulator from wrecking yard.

Started up!!!

Test drive perfect. Drive straight to the gas station for a fill up.

Son is now mowing the lawn!

Notes - I was getting fuel in/out of the rail and plugs soaked with gas. I'm thinking this was the fuel pressure regulator with fouled plugs. Also seems that fuel delivery is now much better than in the past. Going to watch MPG and check plugs in a month to see if its running rich.

Another note is that the fuel pressure regulator I pulled off my 240 didn't have the black rubber grommet on the fuel pressure regulator. The one I installed from the wrecking yard looked much newer and had a black rubber grommet that connects to the fuel rail.

 

Two weeks later the 240 is back to a low rough idle. My $600 original purchase is beginning to frustrate me.

I removed and cleaned the idle air control valve.

To get back to basics I pulled the air cleaner box (dirty - was cleaned in Dec), intake hose, MAF, and hose to throttle body which I'm going to pull and clean again. I did all this last winter and we have only driven the 240 maybe 1,500 miles in that time. I noticed the intake is a little dirty and found what looks to be dirty dark oil in the ripples of the intake house.

I had replaced the flame trap but not the oil separator box this last winter. Is it possible I'm getting oil because of plugged up flame trap?

Anyway I'm going to clean out the throttle body again and the entire intake. I checked the intake house and dont see any wear holes as I found originally when I purchased the car last winter.

I believe the spark plugs fouled again in two weeks so I'm going to buy another set of coppers for $8 later this week and see if it fires up and runs normal again.

One weird thing is when I installed the IPD sport exhaust the idle did drop down immediately to about 550 rpm. Now the car idles about 200-250 then stalls out about 15 to 20 seconds. Maybe unrelated but I keep thinking back to this.

My code when last check was throttle position out of adjustment. Now when I turn the throttle I hear the immediate click. A new sensor is only $26 so I'm thinking about just buying a new one and installing it.

Ideas? Next steps? I'm thinking about removing the entire intake system including fuel injectors. Do the flame trap/separator box, replace the fuel injection seals and maybe try cleaning the injectors.

 

If your plugs keep fouling then it is most likely due to an over-rich condition. When you installed the IPD exhaust, did that include the CAT? Make sure that your oxygen sensor is working properly although I would expect a code to be thrown if it weren't.

I fought an over-rich condition with my '90 240. One thing I found was that I had exhaust leaks upstream of the oxygen sensor. These leaks let in air which causes the ECU to read a lean condition causing it to enrich the mixture.

 

I left the original CAT on the vehicle and cutting off the exhaust just past it. I believe the second pipe has a larger tube called the resistor that was removed.

I'm not aware of any exhaust leaks. I think what I will do is tighten down all the exhaust parts that I installed. Then either test or replace the O2 sensor - could be original.

 

any diag codes ? a 1990 240 has OBD, with a little code reader blinky-box under the hood, any O2 sensor related problems should throw a code.

 

This was the original code prior to installing the pressure regulator from wrecking yard and new spark plugs.

I did run the codes and I got a 2-1-3 Throttle Switch Full load setting Faulty or ground short. Could this make a no start?

 

I wouldn't think so.

 

I meant that was in my original post. In reading that fouled spark plugs can by a symptom both of a plugged frame trap and bad throttle body sensor (due to running rich). Going to try this over the weekend and report back.

 

I picked up new O2 sensor and throttle body sensor from IPD. Found the throttle body sensor they sold me was the wrong part so returned it today.

Pulled throttle body, MAF and all the hoses to the air cleaner. The throttle body is dirty which is a surprise since it was cleaned with about 1,500 miles ago. Intake manifold has what looks to be oil build up maybe from the oil separator?

Picked up a MAF from wrecking yard for $25. Has sticker on MAF that is a Germany Bosch reman. Went ahead and pickup up all the throttle body to air cleaner hoses plus the vacuum hoses from throttle body to the front canister box.

Finally got the oil separator box removed and installed a new box from IPD. This is so much easier with removing the throttle body. Old box looks super dirty and has enough grime over the Volvo label that I'm thinking it could be original.

With the intake looking dirty (see pictures). Is it worth while to remove the intake and thoroughly clean it? I was planning on replacing the fuel injector seals as another possible issue anyway. Looks like a fairly easy job and could help the drive ability. Thoughts?

Anyway I hope I'm down the right track on fixing the rough and low idle issue.

 

the 'throttle body sensor' is simply an idle switch (and possibly a full throttle switch, depending on the year and injection system).

a junkyard MAF has a 50-50 chance of being good. only way I know to test it woudl be to swap it into a working car with compatible EFI (probably LH2.4)... if that car develops problems, thats a bad MAF. if that car continues to work fine, then its probably a good MAF.

 

Yeah I thought a $25 MAF w/ 30 guarantee was worth a shot.

Removed the manifold tonight. Appears oil residue / deposits on two of the ports (see picture on Cyl 4). Going to clean it all out and replace the injector seals. Will install throttle body position sensor, clean throttle body, MAF, etc. then update post.

 

have you done a compression test on this engine? checked the valve clearances?

i'd do that before you go much farther. if you have bum (or tight) intake valves on those ports, exhaust gasses could be blowing back the intake.

 

Update **

Removed the intake manifold
Cleaned injectors
New seals on the injectors
New oil separator box
new intake manifold gasket
new throttle body gasket
Installed wrecking yard rebuilt bosch MAF
replaced oil soaked intake house to throttle body
cleaned throttle body
cleaned MAF

replaced Throttle Position Sensor (TPS) with wrecking yard TPS

The 240 fired right up. Run a little rough (not bad) for about 30 seconds and idle went up to about 550 RPM's and running pretty smooth. For now the 240 is back on the road.

I'm not exactly clear what my idle issue however I feel I may have had some intake leaks. Pulling the intake manifold and injectors is not a challenging job for a weekend mechanic. I cleaned and labelled all the hoses and connectors. Plus now I'm confident I have no leaks at the manifold and injectors.

Pierce - I have not checked the compression or adjusted the valves. Its on the to do list.

 

Didn't see, but did you indeed replace the CTS? If it is out of spec with high resistance, the system will dump fuel into the engine.

 

No I didn't replace the coolant sensor. The 240 is idling really well at start up now at 550 rpm. Throttle response feels much improved. Going to drive it for a week and see how it goes.

I did remove the airbox thermostat and damper. My air cleaner has a hose to the front of the grill now wide open. Air filter remains installed. Its summer an 90 in Oregon and honestly really dont see a need for the airbox thermostat anyway. I will probably reinstall with a new sensor prior to winter. The preheat hose was removed from the 240 when I purchased it.

The 02 sensor is yet to be installed.

 

idle should be more like 700, not 550