Kuroki924

Hey everyone. So I have an '82 924 N/A, I just got it registered a couple days ago so I filled the tank all the way for the first time since I've had it and took it out on the road. (Lord only knows how long it had been since it had that much fuel in it for it was sitting for a few years by the time I bought it) I noticed once the fuel level was just about back to where it was before I filled it up, the car began to sputter and backfire. It stopped after a minute, so I kept going a little farther under the assumption that maybe something just needed to work it's way through the old system, but it started back up again so I pulled over and let it sit in neutral. It was fine upon idle for a minute, then wanted to die if it dropped under 1k rpms. I let it sit for a few and decided to try and baby it back home. I only made it a few miles before she started to sputter and backfire again, so I pulled over again and she quit before I even got it stopped. I let it sit for about a half an hour before trying to start it up, and when I did it started fairly easy, but wouldn't move ten feet without quitting again. So I had her towed home and here I am now. My theory as to why this happened was maybe something in the tank (possible buildup or maybe even chunk of rust?) Broke loose from the inside wall of the tank with the newly raised fuel level and got sucked into the filter, so it clogged. The car ran fine with no issues whatsoever until this began, and I was forced to take it over a fairly bumpy road before it started acting up, so that's why I came to this conclusion. Does anybody else think the same? If so, should I just replace the filter (Again, Lord only knows how long it's been since that was replaced) and flush and clean out the system? If not, what else could I try to look at? Any input is useful at this point. Thanks in advance!

mel_t_vin

The Continuous Injection System that controls air/fuel for the '82 924 works well...when properly sorted. It is, however, susceptible to issues caused by excessive ethanol content in gasoline.

The 944 and later 924 have a panel under the carpet in the trunk to access the in-tank level sender. When the sender is removed, the inside of the tank can be examined. Does your car have this access panel?

Would first cut open the fuel filter. If nothing suspicious is found, would then take your car to German specialist to spec/calibrate your WUR [warm up regulator] which controls fuel pressure under various operating conditions. Your car will not run properly, or at all, if the WUR is out of spec.

Kuroki924

Thanks for the reply man! Well it turned out to be a way over-due for a change fuel filter, along with damaged spark plug wires, to the point where the wire itself was exposed, which is what was most likely causing most of the backfiring. We put new ones on when we first got the car and noticed they've rubbed up against the insulation padding on the inside of the hood, all the way to the metal. We replaced both the wires and the filter and it's like a whole new car, I'm not used to it being able to throw you back in the seat like that, it sounds and idles significantly better too! But how would I go about preventing the new wires from rubbing up against the hood like that? I can't move the dizzy down and cutting the padding so the plugs clear it still won't prevent them from rubbing the hood. Any thoughts for that?

mel_t_vin

Gotta like the simple fixes...well done.

Re: plug wires...don't recall how those wires are routed in the early 924s. Your car is probably missing some factory clips/doodads that hold the wires in place. If you post this question over on the big 924/931/944/951/968 forum, you'll probably get a better response...and a few complimentary reference photos, to boot.