Possible vacuum leak?

[bhw33191]

When i did my engine swap i tested for this already and didnt find anything... When i do a cold start the RPMs seem normal but sort of flutter. Once the RPMs slow down the engine will start to struggle and itll stall if i don't feather the throttle, which means the choke gets kicked off and then i really have to baby it until its fully warmed up.

At first i thought it might be the fact that i don't have the stock air cleaner on (with the exhaust heat thing). But it still does this when the temp is around 70, so it must be a vacuum leak right?

[Blue Bowtie]

It's not necessarily a vacuum leak. It COULD be a vacuum leak, either external from a hose, brake booster, or gasket, or an internal leak from a gasket, EGR valve, or EVAP purge.

But it could also be a MCC adjustment, fuel bowl level adjustment, clogged jetting, saturated float, incorrect TPS setting, and various other causes.

It's fairly easy to check for vacuum leaks, so that would be a good starting point to eliminate that possibility.

[j cAT]

Originally Posted by bhw33191

When i did my engine swap i tested for this already and didnt find anything... When i do a cold start the RPMs seem normal but sort of flutter. Once the RPMs slow down the engine will start to struggle and itll stall if i don't feather the throttle, which means the choke gets kicked off and then i really have to baby it until its fully warmed up.

At first i thought it might be the fact that i don't have the stock air cleaner on (with the exhaust heat thing). But it still does this when the temp is around 70, so it must be a vacuum leak right?

could be vacuum leak. what is the vacuum at the intake port with the engine at hot idle 650 rpm in neutral? should be 17-20 inches.

If low good chance PCV worn or hoses to from this.

the next area would be the carb pull off diaphrams leaking .

the hoses can be checked with a T connector vacuum guage and pinch lines to see if vacuum is being lost on that line/device.


the original air cleaner needs to be installed now...
Still check for proper vacuum at every oil change .

[bhw33191]

Thanks everyone i'll use your advice when i go home next week..hopefully i get this thing in tip top shape before the winter here in maine!