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914World.com _ 914World Garage _ Engine stall at stop signs !

Posted by: DougC Oct 31 2005, 09:48 AM

(2.7L w/CIS) Ok, I replaced my fuel pump this weekend and the engine fired right up just fine. I had to adjust the throttle linkage to get it to idle at an exceptable rpm and not die. When I took it out for a run around the neighborhood it would want to die at the stops. Could this be a vacuum leak? I think my vent hose from the engine case to the oil tank may be slightly too short. Could timing cause this also? While I was initially trying to get it to idle it would sometimes start a pulsating rythem until it would die. suggestions?

PS - oh, BTW it ran really strong during my blast around the neighborhood

Doug C

Posted by: ClayPerrine Oct 31 2005, 09:51 AM

Did you hook up the Aux air regulator?

Also, adjusting the throttle linkage is NOT the way to get the idle up. There is an idle speed screw on the throttle body.

Do you want me to come over again?

Posted by: Jeroen Oct 31 2005, 09:51 AM

don't change a thing... this is a great opportunity to learn to heel-and-toe

Posted by: lapuwali Oct 31 2005, 10:12 AM

The pulsating rhythm is lean surge, and is caused by too lean an idle mixture. There's an adjustment for this on the top of the airflow meter, or you may have another air leak after the airflow plate.

Clay's right in that you don't futz with the linkage to get it to idle. Use the idle air bypass screw for this. If you plumb in the aux air regulator AND IT WORKS, then you should have a higher idle while the engine is cold. If you just cap this stuff off, then you'll need to hold the throttle open with your foot until it warms up, which may take several minutes. Adjust your idle with the engine HOT, as in take it out on the highway for 15-20 min at least.

Timing that's not advanced enough can cause a slow idle, yes. Once you can get the engine to run long enough to get it fully warmed up, set the idle (with the bypass screw), then set the timing, then set the idle again (it will change if the timing was off).

Posted by: DougC Oct 31 2005, 10:18 AM

QUOTE
Do you want me to come over again?

Yes... .... I will PM you.

Aw, believe me I was using the old toe/heel technique as much as I could to keep it lit.

Doug C

Posted by: Ferg Oct 31 2005, 10:46 AM

QUOTE (lapuwali @ Oct 31 2005, 08:12 AM)
The pulsating rhythm is lean surge, and is caused by too lean an idle mixture. There's an adjustment for this on the top of the airflow meter, or you may have another air leak after the airflow plate.

Clay's right in that you don't futz with the linkage to get it to idle. Use the idle air bypass screw for this. If you plumb in the aux air regulator AND IT WORKS, then you should have a higher idle while the engine is cold. If you just cap this stuff off, then you'll need to hold the throttle open with your foot until it warms up, which may take several minutes. Adjust your idle with the engine HOT, as in take it out on the highway for 15-20 min at least.

Timing that's not advanced enough can cause a slow idle, yes. Once you can get the engine to run long enough to get it fully warmed up, set the idle (with the bypass screw), then set the timing, then set the idle again (it will change if the timing was off).

I bet you are running a tad lean... remember last time the mixture was set that motor lived at 5500 ft.

Take it somewhere that has a gas analyser machine and using above mentioned tips for idle and you'll be all set.

Ferg

Posted by: DougC Oct 31 2005, 11:27 AM

Mike, thanks for reminding me of the altitude difference - that's definately something to consider. Actually Clay had to richen it up one notch to get it to start in the first place, it may still need a little more though. This engine sounds much better than I had expected it to especially under excelleration. OK, back to twisting Clay's arm..

Doug C

Posted by: charvey Oct 31 2005, 02:36 PM

check the alternator belt, mine broke at one point and i had the same problem

Posted by: ClayPerrine Oct 31 2005, 02:39 PM

QUOTE (charvey @ Oct 31 2005, 02:36 PM)
check the alternator belt, mine broke at one point and i had the same problem

If the alternator belt breaks on a six, you have bigger problems than a loss of voltage. The fan is not turning, and the engine will quickly overheat.

Ferg, were you the previous owner of the engine?

Posted by: Ferg Oct 31 2005, 02:58 PM

QUOTE (ClayPerrine @ Oct 31 2005, 12:39 PM)

QUOTE (charvey @ Oct 31 2005, 02:36 PM)
check the alternator belt, mine broke at one point and i had the same problem

If the alternator belt breaks on a six, you have bigger problems than a loss of voltage. The fan is not turning, and the engine will quickly overheat.

Ferg, were you the previous owner of the engine?

Yes, I'm the PO, but the PPO owner is who originally built it.
Ferg.

Posted by: ClayPerrine Oct 31 2005, 03:04 PM

That means that I gotta richen the mixture. Time to dig out the CO meter.

Posted by: Jeroen Oct 31 2005, 04:28 PM

QUOTE (DougC @ Oct 31 2005, 05:18 PM)
Aw, believe me I was using the old toe/heel technique as much as I could to keep it lit.

just janking yer chain... but that is how I actually learned it, in a crappy old car that would stall at the lights