Backfire, Simple question from a simple guy... Options

[Coy]

Okay… This might sound stupid…

I just love 914s, but I’m not really that good at working on them. Sure I’ll do brakes and oil and tune-ups, door latches and stuff like that, but when it comes down to actual engine work I just don’t have the proper space or tools, and to be perfectly honest; when the garage is colder than 60 degrees I don’t even have the inclination to do it myself. I used to over haul a Harley every winter and to tell you the truth, I’m just old now; I don’t want to work in the cold. Ad to that the fact that I am totally self-taught as a mechanic and you’ll see that I’m not great at diagnostics, and that I can quickly get in over my head.

So… I have this intermittent exhaust backfire that comes and goes and I don’t know why. It frequently backfires when it’s cold starting before it gets warm, but that stops after just a minute or less.

The car was running great Sunday afternoon (no backfire) so I took it out and had a good time on a twisty little road not far from my house and I have to say… it was running like a champ (I’m tell’n you, I love this car).

So Monday I drive it downtown and it starts doing the back fire thing in earnest. Not only that, but the exhaust seems especially loud. It doesn’t backfire when the accelerator pump is squirting, but it does when it’s at a constant speed. You guys are all real smart; does an exhaust leak at the head have the potential to cause a backfire when the car is running at about 3000 rpm? It's a 2.0 with dual Webbers and hydraulic lifters.

I have other cars, so I’ll just wait till the floor is warmer before I crawl underneath it, but in the mean time does this make sense that it could just be an exhaust leak, or does that kind of crap happen when the carbs are out of sync too? I don’t know squat about dual carbs.

Also... Does anyone in the Portland/Salem area know of a shop with anyone who is epecially good with 914s that can diagnose?

Thanks!

[Coy]

I checked the intake manifolds by spraying starting fluid around the base, it seems good. I have electronic ignition so the points/condenser are out. When electronic ignition fails it just quits running doesn't it?

Fuel sounds like a likely culprit, since Oregon gas quality isn't regulated. It could be that it starves at high RPMs, but it idles okay. I'll have to crawl underneath to change the filter, I haven't done it yet this year. Where does the accelerator pump get it's fuel?

Otherwise a bad ground is always possible. If the ground is loose at the terminal, will it cause the engine to die, or will it just not start? I did have a loose ground wire before and when I fixed that it seemed to fix the intermitten backfire thing (For a while).

See I knew you guys were smarter than me. Thanks!

[TheCabinetmaker]

I have electronic ignition so the points/condenser are out. When electronic ignition fails it just quits running doesn't it?

No! I had a car in my shop last year that I chased a problem for two months. Car would just die till it cooled off. Finally reinstalled points and problem dissapeared.