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914World.com _ 914World Garage _ Fuel disappearing PMO's
Posted by: E. Fry Mar 20 2024, 03:17 PM
I have PMO's on a SC based 3.2 ltr. in my 914. After the car sits for a time the float bowls are empty. Were the heck is the fuel going? Any ideas?
Posted by: BillC Mar 20 2024, 03:57 PM
I have PMO's on a SC based 3.2 ltr. in my 914. After the car sits for a time the float bowls are empty. Were the heck is the fuel going? Any ideas?
Evaporation.
Or, gremlins are sneaking in at night and driving your car without your knowledge and without refueling it....
Posted by: brant Mar 20 2024, 04:17 PM
Evaporation
Carbs are open systems
Unlike modern induction which is a sealed system
And the reason they no longer meet emissions standards
There was also nice a Honda advertisement where two vehicles were separately placed in a sealed room to test hydrocarbons
The mid 80’s Honda was fuel injected and with the motor running
The mid 80’s American car was parked and not with the motor running
The Honda running produced less emissions than the carb’d car which was not running
Posted by: mate914 Mar 20 2024, 06:20 PM
I have PMO's on a SC based 3.2 ltr. in my 914. After the car sits for a time the float bowls are empty. Were the heck is the fuel going? Any ideas?
Mr E. Fry, your car needs driven more often. You will enjoy it. Just starting and warming up helps....
Matt
Posted by: mepstein Mar 20 2024, 06:24 PM
That’s one of the many reasons the industry switched from carbs to FI. My carbed 914 got ~25 on the highway. My FI car got 38.
Posted by: campbellcj Mar 20 2024, 06:32 PM
I have found my car with old Webers really does not do well sitting for more than a few weeks. I've had to unclog gunky idle jets multiple times and unstick dried-up/sunken floats. Lately I make sure to rip it around the neighborhood at least a little bit every couple weekends and it fires right up and runs great.
That being said, definitely check around closely for any seepage on/around the carbs. I would think it'd be visible.
Posted by: windforfun Mar 20 2024, 08:42 PM
That’s one of the many reasons the industry switched from carbs to FI. My carbed 914 got ~25 on the highway. My FI car got 38.
Ditto on the improved mileage.
My old Jensen Healey had a Lotus engine with carbs. Low mileage & a PITA to maintain.
Posted by: stownsen914 Mar 22 2024, 08:02 AM
On the carbed 911 racecar, I have a fuel pump switch. Before shutting the car down after a track weekend, I turn off the fuel pump and let the car run the fuel out of the float bowls. Less fuel to evaporate = less crap left behind in the float bowls to clog up the works.
Posted by: brant Mar 22 2024, 09:42 AM
I drain the bowls after every track weekend now also
Posted by: JmuRiz Mar 22 2024, 12:25 PM
On the carbed 911 racecar, I have a fuel pump switch. Before shutting the car down after a track weekend, I turn off the fuel pump and let the car run the fuel out of the float bowls. Less fuel to evaporate = less crap left behind in the float bowls to clog up the works.
I plan on doing this as well.
Posted by: PanelBilly Mar 23 2024, 09:38 AM
I have the same issue with my PMOs on the 3.0. I let the fuel pump run for a bit and then pump the gas a dozen or more times to get enough fuel in the bowls. FI would have been the smarter choice, but the carbs are cool.
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