Engine Dies on Idle after Warm up

Hello folks,

I'm looking for some help.  I finally have this thing on the road (legally).  Over the last month or so I would run her about 10 mins in my driveway, just idling, some light revving.  Everything seems fine, she's charging, oil at 40 psi, sits around 170F.

So I take her out this afternoon, beautiful day.  I drive for about 10 minutes, everything seems fine.  The temp sits really steady around 170 once the thermostat opens up.

The oil pressure is initially at 40 psi, after about 2 or 3 minutes drops to 20 and stays very steady, even upon acceleration.

After ~10 minutes, when idling, it wants to die.  The oil pressure goes down to 10-15 unless I rev the engine.  It will stay running if I rev the engine, but this is near impossible at a stop with the stock pedals and shouldn't be happening anyway.



W-O carb.  Can't tell you the last time it was rebuilt.

New fuel pump and filter



Any thoughts on what it might be?  Or a test procedure?  I definitely want to be able to drive her for more than 10 mins.

Thanks to all!


Edited by Overland - 15 Apr. 2017 at 1:17am

Overland wrote: Hello folks, I'm looking for some help.  I finally have this thing on the road (legally).  Over the last month or so I would run her about 10 mins in my driveway, just idling, some light revving.  Everything seems fine, she's charging, oil at 40 psi, sits around 170F. So I take her out this afternoon, beautiful day.  I drive for about 10 minutes, everything seems fine.  The temp sits really steady around 170 once the thermostat opens up. The oil pressure is initially at 40 psi, after about 2 or 3 minutes drops to 20 and stays very steady, even upon acceleration. After ~10 minutes, when idling, it wants to die.  The oil pressure goes down to 101-5 unless I rev the engine.  It will stay running if I rev the engine, but this is near impossible at a stop with the stock pedals and shouldn't be happening anyway. W-O carb.  Can't tell you the last time it was rebuilt. New fuel pump and filter Any thoughts on what it might be?  Or a test procedure?  I definitely want to be able to drive her for more than 10 mins. Thanks to all!

My last response didn't go well as in it vanished. The last few issues like this were condensers, coils or the carbs. I hate to be cavalier about it but a search would tell you about what tests people did and the remedy.

working heat riser on exh manny? if stuck you may be boiling fuel.

People were having problems with bad condensers that were new from the store. Internal shorts in them after they warmed up. Somebody cut up several to show how they were constructed and you could see inside how they shorted out.
If you determine that you have bad parts you may have to try another FLAPS to get another brand. Your first place may have a dozen parts on the shelf from a bad run that was delivered to them.

Also, you CAN blip the throttle while standing on the brake pedal.  It's called "heel-and-toeing".  You hold the brake with your toes and hit the throttle with your heel.  Ol' Unreliable requires it frequently.  Alternatively, you could use the hand throttle to up the revs at a stop.  That's the easy way, though.

wadoyado wrote:    In the 10min. before it wants to die, Does it idle fine? How about fast idle? then very fast idle? notice any skips, missing? does it seem to run strong rev up fast? If all that seems fine I would check coil condenser carb like unkamonkey suggested. Faulty coil can work good at first fail as it warms up had it happen before to my late 48 can drive ya nuts. Good luck Joe Wadoyado

It idles fine, comes of the line fine.  It doesn't always want to start right away, very often I end up pouring a bit of gas down the carb.  The odd thing, to me, is that when I do get to start it wants very little choke.

I checked the coil and all resistances are w/in spec.  Primary coil 1.1 Ohm, secondary 8.8 kOhm.

I'll check the condenser next.  I just have a multimeter so I guess I'll just charge it and see if it holds a charge.

Perhaps just rebuilding the carb is my best bet, don't know.

RA472A wrote: I fiddled with a similar issue on my neighbor's 2A.  I replaced his (relatively new ) condenser and it helped for a bit it seemed,but I noticed the new glass bowl fuel pump was not holding any  fuel.  I suspected leaking valve in the pump, so I replaced it with a metal top Carter.  They are a very good replacement pump for the L-head.  Anyway, to make a long story longer, I realized the short hose that went from an in line fuel filter to the fuel pump was brittle and not making a good, tight seal.  Replaced that and runs like a top ever since.  Sooo, check that.  Ethanol fuel is not kind to fuel hose.  If you still have the original steel lines, then tackle the condenser again and maybe again as folks have covered here.

I replaced all the steel lines.  There is some rubber from fuel filter to pump, but brand new.

Ol' Unreliable wrote:   Alternatively, you could use the hand throttle to up the revs at a stop.  That's the easy way, though.

Hand throttle?  Do you mean the choke?


Edited by Overland - 18 Apr. 2017 at 9:41pm

Overland wrote: Hand throttle?  Do you mean the choke?

No, the knob (that should be) to the left of the choke knob on the other side of the dash light and connected to the throttle linkage on the carb.  It is supposed to say "throttle" on it. 

It's beginning to sound more like a carb issue if you need to use that much choke to get it to run.