Carbs and Gas Smell Options

[mmascari]

As stated carbs vent to the atmos,

I have PMO's on my 6 conversion - no char canister, vent goes from tank to engine compartment

I also have PMO's on my 911SC. This one smells even worse as it likes to run rich. Sometimes the fuel smell will seep into the main garage and my wife hates it. No leaks on either of my cars. Best thing I do is leave the door open a little after I pull it back in.

Agree with running the bowls empty if you really cant bear it.

I am going to bring the wife out to the garage later and have her sniff around the car and tell me where the problem is. My nose doesnt work very good. LOL

[914_teener]

Fun fact.
The evaporation "system" on a stock 914 expansion tank (the tank at the filler location) is just a hose the routes down behind the tank and out onto the ground....into the atmosphere.

Its a vapor leak that can/will smell up a garage.

rich

Hunh?


http://www.914world.com/bbs2/index.php?showtopic=108524

[porschetub]

This also brings up the return line vs no return line debate. That pressure has to go somewhere...

Not sure about that,with the LP pump not running there is no residual pressure like an FI car,the fuel bowls are full and stay that way until the engine is running again then the float valves regulate fuel demand from there as set by the float levels .
The OP may have too higher float setting or bad float valves or as mentioned an external leak .
All factors to consider.

[930cabman]

This also brings up the return line vs no return line debate. That pressure has to go somewhere...

Not sure about that,with the LP pump not running there is no residual pressure like an FI car,the fuel bowls are full and stay that way until the engine is running again then the float valves regulate fuel demand from there as set by the float levels .
The OP may have too higher float setting or bad float valves or as mentioned an external leak .
All factors to consider.

I have ran carb'd Porsches and VW's for years always dead headed (no return line) and never had an issue

[porschetub]

This also brings up the return line vs no return line debate. That pressure has to go somewhere...

Not sure about that,with the LP pump not running there is no residual pressure like an FI car,the fuel bowls are full and stay that way until the engine is running again then the float valves regulate fuel demand from there as set by the float levels .
The OP may have too higher float setting or bad float valves or as mentioned an external leak .
All factors to consider.

I have ran carb'd Porsches and VW's for years always dead headed (no return line) and never had an issue

(IMG:style_emoticons/default/agree.gif) done the same for years ,my six engine is no differant .

[mmascari]

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

[porschetub]

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

Well done good on you ,hopefully not a rotten tank or pump leaking,a leaking connection will be easier to deal with,did you have any drips with the pump primed ?.

[mmascari]

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

Well done good on you ,hopefully not a rotten tank or pump leaking,a leaking connection will be easier to deal with,did you have any drips with the pump primed ?.

I had to pull the tank of course. The return fitting was loose. Anyway, I decided to get rid of the return line from the Fuel pressure regulator. Is it true that we can remove this line if we have carbs? I want to make sure.

[rfinegan]

pros and cons ...but sure you can remove the return line on carbs, depending on the pump and regular you have.

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

Well done good on you ,hopefully not a rotten tank or pump leaking,a leaking connection will be easier to deal with,did you have any drips with the pump primed ?.

I had to pull the tank of course. The return fitting was loose. Anyway, I decided to get rid of the return line from the Fuel pressure regulator. Is it true that we can remove this line if we have carbs? I want to make sure.

[porschetub]

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

Well done good on you ,hopefully not a rotten tank or pump leaking,a leaking connection will be easier to deal with,did you have any drips with the pump primed ?.

I had to pull the tank of course. The return fitting was loose. Anyway, I decided to get rid of the return line from the Fuel pressure regulator. Is it true that we can remove this line if we have carbs? I want to make sure.

Good find,the washers are a bit funny on these ,metal ones can leak IMO the fibre washers are the way to go and worked for me on the feed side,I used the return line as a conduit for the power supply wire to my pump and earthed by linking to my crossmember to my pump.
I don't have a return for the above reason and if you have good float valves and the right fuel pressure/ pump you will be good ,strange how some folks run LP pumps that make a lot more pressure than needed even via a regulator,my CB/carter pump only required fine tuning using my Holley regulator and I ended up with 3.3 psi with my Zeniths but understand the Webers run a little higher which think the PMO's are based on.
You will be fine ,cheers.

[mmascari]

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

Well done good on you ,hopefully not a rotten tank or pump leaking,a leaking connection will be easier to deal with,did you have any drips with the pump primed ?.

I had to pull the tank of course. The return fitting was loose. Anyway, I decided to get rid of the return line from the Fuel pressure regulator. Is it true that we can remove this line if we have carbs? I want to make sure.

Good find,the washers are a bit funny on these ,metal ones can leak IMO the fibre washers are the way to go and worked for me on the feed side,I used the return line as a conduit for the power supply wire to my pump and earthed by linking to my crossmember to my pump.
I don't have a return for the above reason and if you have good float valves and the right fuel pressure/ pump you will be good ,strange how some folks run LP pumps that make a lot more pressure than needed even via a regulator,my CB/carter pump only required fine tuning using my Holley regulator and I ended up with 3.3 psi with my Zeniths but understand the Webers run a little higher which think the PMO's are based on.
You will be fine ,cheers.

Thanks, I am using a low pressure Pieburg fuel pump mounted in the front and have a PMO fuel pressure gauge in the engine compartment that feeds each bank of carbs. Pressure is showing right where I want it without the return line.

[porschetub]

Looks like the leak is in the front of the car. I had a carpet my car was parked on and it was soaked in fuel. Tomorrow I am going to climb underneath and see. I relocated the fuel pump up front so there are a few hoses / connections.

Well done good on you ,hopefully not a rotten tank or pump leaking,a leaking connection will be easier to deal with,did you have any drips with the pump primed ?.

I had to pull the tank of course. The return fitting was loose. Anyway, I decided to get rid of the return line from the Fuel pressure regulator. Is it true that we can remove this line if we have carbs? I want to make sure.

Good find,the washers are a bit funny on these ,metal ones can leak IMO the fibre washers are the way to go and worked for me on the feed side,I used the return line as a conduit for the power supply wire to my pump and earthed by linking to my crossmember to my pump.
I don't have a return for the above reason and if you have good float valves and the right fuel pressure/ pump you will be good ,strange how some folks run LP pumps that make a lot more pressure than needed even via a regulator,my CB/carter pump only required fine tuning using my Holley regulator and I ended up with 3.3 psi with my Zeniths but understand the Webers run a little higher which think the PMO's are based on.
You will be fine ,cheers.

Thanks, I am using a low pressure Pieburg fuel pump mounted in the front and have a PMO fuel pressure gauge in the engine compartment that feeds each bank of carbs. Pressure is showing right where I want it without the return line.

You will be good then,cheers.

[targa72e]

Glad you found your problem was just a leak up front. That said Carbs stink. I have a -6 conversion and have had multiple engines and carbs (Webers, Zenith, PMO) and they all smell. There is a lot of gas in the float bowls. If you park a your car fresh from a drive in the garage the heat from the engine will cause the fuel in the float bowls to percolate and evaporate stinking up the garage. I now park mine in the driveway after a drive and then pull in once its cooled down.

john

[mmascari]

Glad you found your problem was just a leak up front. That said Carbs stink. I have a -6 conversion and have had multiple engines and carbs (Webers, Zenith, PMO) and they all smell. There is a lot of gas in the float bowls. If you park a your car fresh from a drive in the garage the heat from the engine will cause the fuel in the float bowls to percolate and evaporate stinking up the garage. I now park mine in the driveway after a drive and then pull in once its cooled down.

john

Good idea, thanks John!

[Justinp71]

Glad you found your problem was just a leak up front. That said Carbs stink. I have a -6 conversion and have had multiple engines and carbs (Webers, Zenith, PMO) and they all smell. There is a lot of gas in the float bowls. If you park a your car fresh from a drive in the garage the heat from the engine will cause the fuel in the float bowls to percolate and evaporate stinking up the garage. I now park mine in the driveway after a drive and then pull in once its cooled down.

john

Yes, I just leave the garage door and side door open for about 45 minutes after a drive seems to do the trick. Also I took the outlet of the engine breather and directed it to the side of the carb rain hats (there is a fitting in the rain hat), this helped cut down overall smell too (recirculates engine breather air to the intake).

[Rufus]

Resurrecting an older thread to add info.

This $135 Rigid sniffer allowed me to quickly locate the gasoline vapor leak PO’s two “experienced professionals” were unable to find on 9140431482. The greatest source was a SS braid hose; possibly due to internal rubber hose incompatibility with E85 gas?? Or maybe shift mechanism chafing the SS braid??? Just guesses. The SS hose routed thru the cabin tunnel. The leak found worst near the shifter.

And BTW: the “rubber patch” solution reported by PO in 2013 as a fix, failed the sniff test by women in my household.

[r_towle]

Porsche 356 has carbs and a fuel shutoff underneath the dash.
With today’s fuel, I find it best with any carbed engine to turn off the fuel supply while the engine is running and let it suck the carbs dry.

Also, when going to a car show, simply putting tennis balls into the intake stacks helps a TON to keep the hot fuel from evaporating and smelling things up.

Today’s gas has a lot of ethanol. That evaporates really fast.

Rich

[Rufus]

Porsche 356 has carbs and a fuel shutoff underneath the dash.
With today’s fuel, I find it best with any carbed engine to turn off the fuel supply while the engine is running and let it suck the carbs dry.

Also, when going to a car show, simply putting tennis balls into the intake stacks helps a TON to keep the hot fuel from evaporating and smelling things up.

Today’s gas has a lot of ethanol. That evaporates really fast.

Rich

100% Agree! In addition to an ignition shut-off, I added a FP cutoff for limiting fuel level in the carb floats before parking in the garage. I also use E0 gas exclusively

[JmuRiz]

…I also use E0 gas exclusively

Lucky duck

Yes the petcock on the 356 is nice. Even with that the e10 here (even with marine stabilizer) it caused the PO’s tank lining of the original tank to fail and clog up my freshly cleaned and redone from petcock downstream refresh last month.

[73-914]

Porsche 356 has carbs and a fuel shutoff underneath the dash.
With today’s fuel, I find it best with any carbed engine to turn off the fuel supply while the engine is running and let it suck the carbs dry.

Also, when going to a car show, simply putting tennis balls into the intake stacks helps a TON to keep the hot fuel from evaporating and smelling things up.

Today’s gas has a lot of ethanol. That evaporates really fast.

Rich

(IMG:style_emoticons/default/agree.gif) This is why I use alcohol-free gas