Okay, I will try to give the Reader's Digest Condensed version: My 1980 242 DL/GT (all stock B21, K-Jetronic f.i. system) has been super-reliable (zero problems) for the 15 months that I have had my car. Today, when trying to start the car (not at home, naturally), there was a slight backfire while cranking the car. Finally got it started after much cranking and swearing at the car, but the car will not idle now. I have to keep my foot on the accelerator pedal to keep the car running. Runs very rough at rpm's below 2000, but is a bit better above that. While driving, the car has a bit of a "trailer-hitching" feel to it. What happened, and how do I fix it?

I have checked for any obvious loose/broken vacuum hoses or anything else obvious wrong with it. Also checked all fuses, none blown. I have almost no experience troubleshooting K-Jet systems (no previous need to, the car has been perfect until today) though I do have quite a bit of experience with L/LH-Jetronic systems. Also looked in 2 Fuel Injection service manuals and my Haynes manual this afternoon, but none of these symptoms seem to be described in the books I have. Thanks for any insight you might have as to the nature of my problems.

Billy McCaskill
billy383z@cox.net

back to daily driving my non-daily-driver V8 powered 1977 Datsun 280Z until I can sort out my 1980 Volvo problems...

I know you mentioned looking for the obvious hose popped off, but "slight backfire while cranking" makes me wonder if the not-so-obvious rubber boot between throttle body and airflow meter was dislodged or damaged.
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Art Benstein near Baltimore

Hi Art, I have not yet had a chance to go out and look at the boot between the Airflow Meter and the Throttle Body. We had a tremendous amount of rain here in Louisiana in the past 2 days, but it looks like today might be a good day to go out and look at the boot to see if it dislodged or maybe split. Thanks for the advice.

Billy McCaskill

Thanks to all who responded to my question about the K-Jet problems. Turns out you were right, hillbilly! When the engine backfired, the hose connecting the aux. air bypass valve to the intake manifold had been dislodged. For those not familiar with the size of this hose and the related vacuum leak it caused, the inside diameter of this hose is somewhere around 5/8" in diameter. I slipped the hose back on, and the car is good as new. Well OK, maybe not good as new, but good as it ever has been since I have had the car. The odometer has never worked (stopped at 138K miles) since I have owned the car, and the previous owner reports that it had not worked for MANY years prior to me obtaining the car. Best estimate is about 300K miles... and still going strong!

billy242
happily motoring in my Volvo again!

I agree, and I'll bet you breakfast that it's just a loose hose somewhere on the intake.
steve

Since you have to give it a lot of air with the pedal to keep it running fast, I would guess it's getting too much fuel. Excessive Control Pressure is a possibility, but best analysis would begin with a K-jet Pressure Gauge set up, which you probably don't have (about $65 at JC Whitney last I knew).

But here are a couple of K-ket URLs that may help you understand what's going on—

1)3Mb mpeg file showing fuel distributor/airflow meter in action???
NOTE: Don't see the action anymore, but still a good tutorial

http://www.volvoclub.org.uk/tech/fuel_injection/k_jetronic.htm

2)Kjet stuff posted by Erling 4/8/5

http://www.users.bigpond.com/INTERJECT/KSITEPLN.HTM
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

I wonder if that might not be a leaky injector problem or maybe the cold start injector isn't shutting off.

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'81 GLT 245 @ 259K; '83 DL 175K

Hard to say, but it sounds more severe than that to me. I would start by checking System and Control pressures, if it was mine. But I haven't really worked on a K-jet problem in some time, so I could be way off base.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Thanks to Bruce Young and Al A. for their replies. I will go out and do some more checking and poking around later after the ground dries out a bit, we had over an inch of rain overnight here.

I am seriously considering converting the car over to EFI instead of the K-Jet system. I have a complete intake with injectors, etc from a B23 motor, and a couple of complete MegaSquirt EFI computers built and sitting on my shelf. Shouldn't be very difficult to make this swap, anybody ever done this?

Billy McCaskill
1980 242

Try misting water from a spray bottle around the intake manifold gasket and the injectors (engine cold but running).
Also, check the air inlet hose for cracks...I think it's supposed to be free of leaks.

Al A., '84 245GLT, advanced entropy labrat