sundeezy

I have an 85 GS and it has the infamous 3k hesitation. I was reading a sticky about it last night explaining that the hesitation is caused by the delay of the ecu switching the fuel pump to full power before the secondaries kick in, and during that time, the primaries are not getting enough fuel causing the stumble/ hesitation.
So my question is, could I cut the spring in the secondary diaphragm and pull it out to the original length which would cause the secondaries to kick in sooner. Would this get rid of the stumble due to the secondaries kicking a few rps before the fuel pump switches over to full power?

rotornoob

iTrader: (2)

If it is a gs there is no ecu. The secondaries are vacuum controlled. The gsl-se was the only first gen with an ecu.

sundeezy

Ah, ok I was mistaken.

sundeezy

Do you think having the secondaries come on sooner would alleviate the hesitation?

Cookboy

iTrader: (10)

I don't think so. Driving with mechanical secondaries has taught me that there is no upside to opening the secondaries under roughly 4000 rpm.
With 4 85 GS or S models since 1988 I have never experienced the hesitation of which you speak. Some maybe at 1500 to 2000 starting out, but carb rebuild has always cured it.

rotornoob

iTrader: (2)

^ this guy has it right. Carb rebuild seems to solve the majority of these types of issues.

sundeezy

Good News Everyone! I figured out the stumble! I had to remove the distributor and shift it over one gear. I re-timed it and the car runs like a top now. Super stoked! No stumble and smooth acceleration through the entire power band. This also fixed a weird chirping noise under heavy load which I was told was most likely pre detonation, which would make sense. Thanks for everyones help and suggestions!

Cookboy

iTrader: (10)

Splendid! Thanks for reporting the fix.