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MurphinDC

Engine Stalls After Running or Idling for a While

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New to the forum as I picked up a 71 with a 74 Tii engine in it, but I'm running a brand new Weber 32/36.  Car came with a 38 but it was taken out as a first step to address the issue.  Car runs great at idle from being cold for 15-20 min then sputters and dies.  I can drive it for 15-20 min and then I'll park it and after 5 min it sputters and dies.  If I drive it too long it will eventually sputter and die and I have to let it cool to be able to start it back up.  PA installed an auxiliary fuel pump in the trunk and the symptoms I describe happen when using it or relying on the mechanical pump.  BTW the mechanical is still hooked up when I use the auxiliary.  It was not removed by the PA.  What I've done so far to address the issue: 

  • Put in a new sending unit,
  • New mechanical pump
  • Added a Malpassi Fuel King regulator after the mechanical pump.  Played with the Malpassi but still have the issue.  Thought maybe the 32/36 was getting too much PSI.
  • Added a riser to the Weber from Pierce Manifolds.  
  • Lastly, changed the oil as it looked gray, which doesn't sound good.

 

At my wits end so any help is appreciated.

 

Murph

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Sorry, keep thinking of repairs I did..

  • Blew out fuel lines 
  • Removed and cleaned fuel tank, had some rust in there and thoroughly rinsed out four times with gas. 
  • Just noticed that the new sending unit is not working.  Thought I was low on gas but I wasn't!

Seems like a vapor lock once the engine heats up.

 

Thanks

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Check the float and needle valve. Easy to see by looking down the primary when the engine is idling. If you see drops of fuel dripping onto the throttle plate, your float is not "floating"  or the needle is not seating, causing a rich mixture that eventually stalls the motor. 

Replace the old plastic float with a brass float (alcohol resistant). The "old" plastic floats don't hold up well with modern gas.

Also check the small filter inside the large nut under the fuel intake on the Weber.

Your picture #0653 shows a black plug on the vacuum nipple (under the fuel filter). Is this closed? Looks like just a piece of open vacuum hose. Check the one on the #1 runner as well.

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28 minutes ago, John76 said:

 

Check the float and needle valve. Easy to see by looking down the primary when the engine is idling. If you see drops of fuel dripping onto the throttle plate, your float is not "floating"  or the needle is not seating, causing a rich mixture that eventually stalls the motor. 

Replace the old plastic float with a brass float (alcohol resistant). The "old" plastic floats don't hold up well with modern gas.

Also check the small filter inside the large nut under the fuel intake on the Weber.

Your picture #0653 shows a black plug on the vacuum nipple (under the fuel filter). Is this closed? Looks like just a piece of open vacuum hose. Check the one on the #1 runner as well.

 

Agreed. Also note that the float settings are different for plastic vs brass so double-check the specs. 

 

Next time it stalls pull a plug or two out. If they're wet with fuel, it's flooding. Loaded with dry black soot suggests rich depending on fuel but modern additives leave most of the plug except for the tip of the electrodes pretty black even when the mixture is right. If everything is dry white, tan or brown, lighter than say chocolate brown, it's running lean.

 

Whats between the pressure regulator and the carb, besides rubber hose? And with the pressure regulator, keep in mind you want less than 3psi, preferably no more than 2.

 

 

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Try cleaning out your secondary idle jet...Located on the driver's side of your carb. Just remove the brass plug. Remove the jet, clean out the opening until you see light....Easy enough to do

 

ira

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I'd replace that pertronix with points and condenser to test or just replace it. IMHO I have a hard time consolidating carb/fuel problems with the 20 minute run time for example if you float level is high or low it always is from cold start to running temp, same with plugged jets etc. where heat is a common factor in electronic failure. Just my take on it.

.

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This issue surfaced with the old car...a 38 and that was why the PO decided to install the new 32/36 so It consistent with both.  I assume that has to tell us something. 

 

John76:

The carb is brand knew, installed last week by the PO so I assume everything is clean and not fouled. East coast time so I will check for a drip, screen and plugs.   Have to assume the float is set correctly but guess I will check that as well.  Both plugs on the manifold are plugged.  I assume this is correct?

 

Jimmy:

I will check the plugs in the AM.  Two of the OLD plugs were black.  My assumption is that it is running rich.

"Whats between the pressure regulator and the carb, besides rubber hose?" Nothing.   "And with the pressure regulator, keep in mind you want less than 3psi, preferably no more than 2."  Fiddled with the pressure regulator I think too much so I need to run a check of the pressure with a dial in order to reset the Malpassi.

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Son of Marty:  Sorry not sure I follow you.  Could be because of the 10 hours of time under the hood today...:-). Assuming your saying it's an electrical issue, e.g. points, condenser etc.  I like the idea of replacing the Pertronix with points and condenser to see if that is the issue.  I noticed the PA has a standard Bosch coil with the Pertronix and was wondering if that may be the issue as I read it needs 3.0 OHM to run on 4 cyl while the Bosch only puts out 1.8, I believe.  

 

Murph

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