76 2002 weber, mech. fuel pump, dies at warm idle sometimes

[derimc]

my 1976 bmw 2002 has an e12 head and weber conversion. It runs fine 90% of the time...but, sometimes (even after driving on the freeway and car is warmed up well) it wil die when sitting at idle. Then it is hard to start. I can take off the air filter and cover the carb with my hand, crank it over, and this seems to provide enough vacuum to pull gas into the carb. After doing this a few times it will start right up again. Any ideas as to what the problem could be?? Any help is greatly appreciated. Thanks

[Napes]

If you have a 32/36 carb, remove the idle jet from the passenger side of the carb and blow it out w/ compressed air (or use a fine wire to make sure it's not clogged). If you're running a 38/38 then you have idle jets on each side of the carb. And, also check the float level to verify that it's correctly adjusted (search the archieves for proper setting). I'd be inclined, without more info, to suspect the floats as the problem.

Bob Napier

[derimc]

Thank you for the advice. I have a 32/36 weber. I will review the archives and attempt to do what you are suggesting. I'll keep you posted. Thanks again.

Denny

[derimc]

So,

I pulled the jet and cleaned it as you suggested (it was turned totally tight and later I fooled with it as I thought they were to be backed of 2 turns...). I reinserted it and started the car. I let it warm and drove it for awhile. I then let it sit at idle.....and sure enough, about 15 min later, it died. Sounds like I need to check the floats then? Appreciate the help. Thanks.

[Guest Anonymous]

Another line of troubleshooting is focusing on the idle adjustment. It sounds like your timing may be retarded a bit, or you idle mixture leaned out more than it should. Remember, the '76 smogger has a temp switch that switches one of the mag valves. Review what the temp threshold does. It may retard the timing for smog purposes. Or it may be connected incorrectly, revies the diagram and make sure the vacuum pipes are correct. Determine if the temp switch that signals the mag valve is actually active at the temp specified. Make sure that there are no vacuum leaks in the system. For running purposes until you verify the smog hoses and vacuum system, try resetting the idle when the engine is at the hot temp where it fades.

Since the '76 w/ smog eqt. has a dusl action distributor advance, make sure your setting the idle with the retard side connected and the advance side disconnected and hose plugged. Then set the ball marker at 0 deg.

That gives the correct advance when the system is reconnected. And make sure your dwell is 59 deg. (about .016") Clean the points and make sure the condensor is not bad (leaky).

I know this is a lot of information but make sure your valves are set

at spec. (cold).

Finally, any water or solvents or 'treatments' in the fuel may change the RPM that the engine idles at. Alcohol, or stp, etc., have an effect on smooth idle. Once the sympton has been treated with the additive, just run on straight fuel. Try an octane rating higher that you typically buy.

Good Luck.

[Guest Anonymous]

oh yeah, i forgot...make sure the automatic choke is out of the way when you set the idle. Otherwise, when the engine heats to OT the lack of choke makes the idle lower....sometimes in the stall range.

[bigjim5551212]

so you have to find out if the carburetor is flooding or running out of gas. what you could do, is to take the lid of the carb off when you have the probem next. If the carb has no gas in it, then it is a fuel pump/filter problem. If there is gas running into the carb from the auxilliary venturies when the engine stalls, then the carb has a fuel pressure/sinking float/worn needle valve problem.

Remember, no more than 3 psi. Holley regulators are crap. The only good one is the Malpassi Filter King. We have those, $60 including shipping. Call me at 1-800-665-5031

[derimc]

Well.....just talked to Jim from overseas auto and bought a new mechanical fuel pump....arrived fast, going to put it in now. Also had the exhaust leak fixed.... I'll keep you posted on how this effects my fuel delivery problem.....

Thanks to all.

Denny

[derimc]

Well it all looks good so far........ no issues. New pump is delivering fuel great.

[derimc]

Well here we are weeks later and the car has not died once while idling. Must have been the mechanical fuel pump. These cars are great. LOVE IT! Thanks to all who helped, my sincerest appreciation!

Denny

[bigjim5551212]

glad to hear this.