|
|
|
Ok, to the point: 1980 242 DL daily driver, B21F, K-Jet, M46 trans, mileage unknown but very high.
Just recently (within the past 2 weeks), the car has developed an intermittent power loss while driving, and also a poor idle quality. Car seems to idle/run just fine for about 5 minutes, then the car begins to lose power. Acts as if you are trying to accelerate from 25mph in overdrive but without the shuddering. Will barely rev to 4,000 rpm, and will only do that very unwillingly. If I shut the car off and leave it for a few hours, it will start up and run just fine for 5 minutes or so before the power loss returns. Rarely, the loss of power and poor idle will resolve itself while driving, only to return very shortly. When the car runs poorly, the coolant temperature will go up slightly, indicating that perhaps the fuel mixture is going lean?
Anybody have any clue as to what's going on and where I should begin to look for the problem? Since it's my daily driver and I am scheduled to make an 800 mile trip with this car in a few days, it's imperative that I figure out what's going on and get it fixed. Not fixing it could make for a miserable trip, providing I even reach my destination...
billy242
|
|
-
|
|
|
Hi Billy
I am not the one to help diagnose and my only similar experience turned out to be the mass air flow meter. Since you have a time-sensitive situation I recommend you call a friend of mine. Brad @301-762-1553. He owns Volvo Specialist in Rockville, Md., right outside D.C. He is expert in Volvo repair and I would trust him with my life. I guess in a manner of speaking, I have with my Volvo. In return (kidding) I did just post a thread and am getting ready to crash for the night, but do you know if I need any thing other than a new gasket and clean surfaces to re-install my valve cover gasket? I thought I remembered a half-crescent shaped rubber seal at the front of the cover but can't find it and the new gasket came by itself from Volvo. If not, I'll wait til Monday and then I'll call Brad, too as he is my guru. Good luck. Ken
|
|
-
|
|
|
Hi Ken,
My car is a 1980 with K-jet fuel injection, and as such has no MAF. I think that if I had EFI (L-Jet or LH-Jetronic) that my issue might be much easier for me to diagnose. I have a lot more experience with that...
As far as your valve cover gasket issue, when I replaced mine, I simply cleaned the head surface and the cover surface until there were no remnants of gasket or sealer. I used a few small dabs of clear RTV on the valve cover side simply to hold the gasket in place while I put the bolts in and tightened them down appropriately. On my B21 engine, there is a semi-circular plug but it is in the rear of the head near the firewall, not in the front. My valve cover gasket came with said plug. When I installed it, it leaked oil badly. I had to remove the valve cover, pull the semi-circle plug, thoroughly clean it (and the recess for it in the head and the valve cover) off, and smear clear RTV all around the circumference of the plug, and reinstall it. I let it dry for 5-6 hours before starting the car to that the oil didn't infiltrate the RTV and prohibit it from setting properly. That's my experience with valve cover gaskets on the Volvo. Not sure what year or engine you have, your car might have a plug in the front of the head...
billy242
|
|
-
|
|
|
Hi Billy
I have to hurry as I smell something great coming from the kitchen. ( We slept in late as I was up til God knows when fiddling online with Brickboard..it can be kind of addictive and interesting)
Thanks for the detailed help you sent along. Mine is a 1990 240 and you were right about it all. I particularly appreciated the advice about the rear block. I will follow the instructions and benefit from your experience but mostly from your corrections. I am learning!! I had our shop at Mercedes paint my valve cover black with white letters and you ought to see it. If I can learn how I will send pix from my phone cam. thanks again
|
|
-
|
|
|
Ok, I spent all afternoon trying to diagnose my intermittent problem with no success. I used jumper wires on fuses #5 & #7, and apparently both fuel pumps are working. However, pulling fuse #5 (in-tank pump) while the car is running makes absolutely no difference whether the car is running properly or erratically. I can start the car with #5 removed. However, if I disconnect the yellow/red wire under the rear seat, the car will die and not restart. Reconnect it, and it starts and runs. From this, I presume that my in-tank pump is working. Why would pulling the #5 fuse not make any difference?
What kind of current draw should the in-tank pump be pulling? I pulled the fuse and put my ammeter in it's place and the in-tank pump is pulling only 1.38 amps. My meter is only protected to 10A, so I did not try to measure the current draw of the main pump at fuse #7 (rated at 16A). Also checked for voltage drop across the fuses, and there was none (13.05v on either side of each fuse, both #5 and #7). Fuse #7 remains too hot to touch while the car is running... tomorrow afternoon I will go under the car and check for corrosion at the terminals of the main pump.
Also, while searching around under the hood I noticed some sort of component that appears to be some sort of vacuum switch ( about 40mm in diameter, white cap on one end and on the other end are two vacuum lines and two wires, one green and one black) that I cannot find in my Haynes manual wiring diagram. It is attached to the center of the firewall just above the rear of the cam cover. What is this, what does it do, and does the vacuum operate the switch or does voltage operate a vacuum diagphragm?
http://i238.photobucket.com/albums/ff297/billmz/v21.jpg
At this point, I'm still scratching my head. The car loses power after approxiamtely 2 to 5 minutes of running (depending on engine temp), will run/idle poorly (idle speed drops @ 300 rpm from normal) for approximately 5-10 minutes (makes merging onto the interstate really interesting), then will run properly again after that. Still puzzled... any more suggestions???
sorry for being so long-winded!
Billy McCaskill
|
|
-
|
|
Just one more thought, based on symptoms that sound very similar to an experience I had: Lean because tank pump failed and warm fuel cavitating in main pump. Noisy main pump, hot (ouch) fuses 7 & 5. Very warm day.
--
Art Benstein near Baltimore
There is no psychiatrist in the world like a puppy licking your face.
-Ben Williams
|
|
-
|
|
|
Hi Art,
I just came back inside from checking fuses 5 & 7 in my car, and found #7 to be too hot to touch but #5 was cool. I couldn't really hear the main pump making noise, as I have an exhaust leak that is loud enough to mask any noise the pump might be making.
Given that fuse #7 is blistering hot, should I suspect the transfer pump inside the tank is bad?
Billy McCaskill
billy242
|
|
-
|
|
|
I hate to send you on a wild goose chase, but the hot fuse could simply be poor connections at the fuse block, or even corrosion on the fuse ends themselves. It was just one of the symptoms of my hot day at the side of the road.
To determine if the tank pump is operating, use a jumper between 5 and 7 to operate the pump(s) without running the motor. Listening at the filler pipe should tell you, but if it is too noisy in your locale, you may want to temporarily disconnect the main pump (not sure, but I think under the back seat there is a plug like on LH cars) to determine which pump you are hearing. You could also disconnect the tank pump in the trunk or under the wagon's plywood.
There are some hints on tank pumps here: http://cleanflametrap.com/transferPump.htm
--
Art Benstein near Baltimore
Be wary of strong drink. It can make you shoot at tax collectors, and miss.
|
|
-
|
|
|
Thanks Art,
I will pull the fuses and use a jumper wire to test the pumps as detailed in your link. I'd hate to have to buy and replace a pump that isn't faulty to begin with. Will test it this afternoon (will also try to patch up my exhaust leak so I can hear if the pumps are running or not)...
Billy McCaskill
|
|
-
|
|
|
Thanks Art, tomorrow I will check the fuses to see if they are excessively hot and I will lay beside the car near the rear axle to listen for unusual or excessive noise coming from the main pump while the car is running. Hopefully between all of these helpful suggestions, I will be able to figure out what's going on with my car and get it resolved...
Billy McCaskill
|
|
-
|
|
|
You might take an ohm meter and check the heating element in the control pressure regulator.
As it warms up it leans the overall mixture and helps to lower the idle along with the auxilary air valve. These two items mimic the engine warming up. They use heaters to close off air and lower the fuel pressure.
The temperature gauge may be from extra fuel that may create more heat. A warm engine needs to be leaner and these could make it run like the choke is on.
The control pressure regulator is usually reliable so it may be just the connector to it. Check for corrosion and voltage there.
Your description of idling poorly, is a poor description to work from on here.
If you are thinking lean, then look for a vacumm leak and what could change that, after five minutes...???.... it drops me there unless its the intake manifold gasket getting bad?
Does your car have a frequency valve mounted in front of the brake booster? If so do you hear it buzzing all the time when the car runs? They are on Lamda Sond cars. There is a relay on the left front fender that could be dropping out. Again rare but thought you might listen for it.
That is all I can think of since I have a 78. Yours might be a little more sophisticated.
Phil
|
|
-
|
|
"When the car runs poorly, the coolant temperature will go up slightly, indicating that perhaps the fuel mixture is going lean?"
Good logic there Billy, but since fuel pressure(s) are at the heart of K-jet operation almost any K-jet problem analysis should start with fuel pressure measurements. And as you probably know, these pressure tests require special gauge plumbing that includes a selector valve.
I know this doesn't mesh with your time available, but the good news is that JC Whitney now has that gauge setup at the lowest price I've ever seen. Click Here
I paid over $100 including shipping years ago for my gauge.
And Art Benstein has put together an excellent pictorial on how to connect and use the K-jet gauge HERE
I could guess that maybe the Control Pressure Regulator is leaning the mixture (from cold running enrichment) too much for some reason, but the gauge is required to prove or eliminate that hunch.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
Thanks guys for the responses regarding my intermittent issues. I forgot to add in my original post that when the loss of power/ erratic idle is happening, there is also a popping sound in the exhaust on deceleration, also adding to my hunch that the mixture is going lean. It's the INTERMITTENT part that is troubling me...
That is a great price on the K-Jet pressure test kit from JC Whitney but as you mentioned Bruce, I'm in a bit of a time crunch so don't have time to order it and do the testing prior to my leaving on my trip. Also the link to Art's site detailing the testing procedure is going to be of great help when I can get around to checking my system pressures. Perhaps I should order it and have it shipped to where I am going, as I already have a Bosch fuel injection service manual at that location too. As it stands, I guess I will chance it and attempt to drive the 800 miles and pray that I get there OK.
I'm pretty sure that my car does have a frequency control valve (it is a LambdaSond car), but I've never heard any buzzing noise coming from under the hood. I will go out later and check for vacuum leaks (already did a visual check for obvious cracked/broken/disconnected lines, etc) to see if I can rule that out as the cause of my problems. I also checked my ignition system today and found a bad cap and rotor (replaced them already, didn't fix the problem), and also checked the mechanical and vacuum advance mechanisms and found them to be in good working order. I also checked the fuses to the fuel pumps and they were also good. So I guess that aside from a vacuum leak, it looks like I should concentrate on the control pressure regulator.
Thanks again for the responses, and I will let you know what I find when I get the chance to test it.
billy242
|
|
-
|
|
|
Given the time pressure, I'd put emphasis on Dave's suggestions -- as being more "real world" than a wonky Control Pressure Regulator. The CPR could still be playing its part, normally leaning the mix based on time and temp. But that could mask a vacuum leak when cold, then give it the upper hand when warmed up.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
The simplest and I think most likely cause of your running problems is a vacuum leak--especially the bellows between the fuel distributor/air plate assembly and the throttle housing given that it sometimes self corrects. Other vacuum leak areas can be checked with a water bottle spritzer (safest) or spray carb cleaner (potentially dangerous). Spray around the intake manifold ports and the injectors. Water spray will make the idle worse/ carb spray will increase the idle speed. Beyond that you will need to check fuel pressure--from cold to hot. -- Dave
|
|
|
|
|
