3.2 carb engine fire running again, It lives again. Options

[930cabman]

Zoinks!

At least you did find the smoking gun.

It may not be the floats fault, more what someone stored the car with. Bad gas, wrong gas?

Either way, seems like a straight forward fix.

I had a line on a CIS 911 crack many years ago. Sprayed fuel everywhere while driving. First stop sign, could smell it. Pulled over shut down. No fire = damn lucky.

I have found it's better to be lucky than good

(IMG:style_emoticons/default/idea.gif)

[mate914]

One float dry the other soaked in gasoline two hours. The one that soaked in gasoline weighs more than the dry one.

[nditiz1]

But does it still float?

[TomE]

But does it still float?

Yes it still floats but it started at 12 grams too before being soaked in gas. The other float stayed 12 grams soaked or dry. Maybe that is within tolerance but you would think both would either increase in weight or stay their dry weight?

[blabla914]

Interesting stuff.

While it's curious that one of your floats gains 3g when soaked in fuel and the other does not I think there is very small likelihood this caused a fire. It still floats. The fuel level may be slightly higher in the bowl with the heavier float, but if it still floats and the float mechanism, needle, seat, etc are working properly it's still going to shut off the fuel supply.

Additionally, part weight is used to optimize the mold filling process. 3g is a very small difference. I'll bet if you weighed 30 new in bag floats you would see 3g variation.

Now I also think you would be crazy to put those old floats back in service. I mean two of them were in a fire. you have the whole carb apart anyway. I would go through them.

That said I think something else is the cause of your fire. I would carefully go through the carbs paying attention to all plugs, seals and gaskets. Then I would methodically set them up paying special attention to things like fuel pressure and float level.

Paul Abbot's Performance Oriented website, Weber Carburetors by Pat Braden and the Haynes Weber Carburetor manual are all good sources for general rebuild instructions (yes I know PMOs are not specifically in there, but lots of stuff is the same) and setup methods.

[mate914]

That is my plan this weekend. Still waiting on parts from Empi.

Matt

Interesting stuff.

While it's curious that one of your floats gains 3g when soaked in fuel and the other does not I think there is very small likelihood this caused a fire. It still floats. The fuel level may be slightly higher in the bowl with the heavier float, but if it still floats and the float mechanism, needle, seat, etc are working properly it's still going to shut off the fuel supply.

Additionally, part weight is used to optimize the mold filling process. 3g is a very small difference. I'll bet if you weighed 30 new in bag floats you would see 3g variation.

Now I also think you would be crazy to put those old floats back in service. I mean two of them were in a fire. you have the whole carb apart anyway. I would go through them.

That said I think something else is the cause of your fire. I would carefully go through the carbs paying attention to all plugs, seals and gaskets. Then I would methodically set them up paying special attention to things like fuel pressure and float level.

Paul Abbot's Performance Oriented website, Weber Carburetors by Pat Braden and the Haynes Weber Carburetor manual are all good sources for general rebuild instructions (yes I know PMOs are not specifically in there, but lots of stuff is the same) and setup methods.

[Justinp71]

@mate914 Scary situation, glad you put out the fire. Have you checked the fuel lines for cracks/leaks? What was actually burning during the fire when you were putting it out?

Also it is unclear in your test did the float still float in gas after sitting for 2 hours?

[mate914]

The carburetor was on fire inside the manifold and carb itself. Then the filter lit on fire.
Matt

@mate914 Scary situation, glad you put out the fire. Have you checked the fuel lines for cracks/leaks? What was actually burning during the fire when you were putting it out?

Also it is unclear in your test did the float still float in gas after sitting for 2 hours?

[mate914]

PMO tech update
Floats need to be under 12 grams . The float I had that started fire is 15 grams.
Still pointing finger at float. Matt (IMG:style_emoticons/default/flag.gif) .

[porschetub]

PMO tech update
Floats need to be under 12 grams . The float I had that started fire is 15 grams.
Still pointing finger at float. Matt (IMG:style_emoticons/default/flag.gif) .

Certainly looks that way,honestly had no idea the were molded foam,assumed they would be hollow as the old style metal floats were on many older carbs ,my DCNV 36's were brass on my 1.8 engine .
Anyway the outcome would be the same if the float valves couldn't hold a seal,no mention of fuel pressure ? could be a key point.

[porschetub]

PMO tech update
Floats need to be under 12 grams . The float I had that started fire is 15 grams.
Still pointing finger at float. Matt (IMG:style_emoticons/default/flag.gif) .

Certainly looks that way,honestly had no idea the were molded foam,assumed they would be hollow as the old style metal floats were on many older carbs ,my DCNV 36's were brass on my 1.8 engine .
Anyway the outcome would be the same if the float valves couldn't hold a seal,no mention of fuel pressure ? could be a key point if too high ?.
Cheers.

[mate914]

PMO tech update
Floats need to be under 12 grams . The float I had that started fire is 15 grams.
Still pointing finger at float. Matt (IMG:style_emoticons/default/flag.gif) .

Certainly looks that way,honestly had no idea the were molded foam,assumed they would be hollow as the old style metal floats were on many older carbs ,my DCNV 36's were brass on my 1.8 engine .
Anyway the outcome would be the same if the float valves couldn't hold a seal,no mention of fuel pressure ? could be a key point if too high ?.
Cheers.

Fuel pump is a Mallory 29256 Model 110 Fuel Pump 7psi. with regulator adjusted down to 5-6PSI . I will bump it down to 4-5 psi when setting floats this time because it is more of a street car than the old track car only it once was.

Matt (IMG:style_emoticons/default/flag.gif)

[nditiz1]

Set the pressure to 3.5.

Also, I have never weighed my floats, not that you shouldn't, just that I assumed they work because they float. Lastly, when bench setting them, if you can, run fuel to them and get the floats (4) all on the sand blasted dot.

[TomE]

Big question with the float now is why did it crack and why does it hold fuel in it. Matt and I know the car very well and the previous owner. The car did sit for over two years in an unheated garage. It most likely evaporated the fuel that did surround the floats after a year or so. Running this garbage they call gas with corn liquor in it most likely did not help. We have seen and heard of countless small engine carburetors ruined from the ethanol especially on outboard motors. It may just simply be from being dry after sitting for so long. Probably a combination of things but definitely something to look out for.

[porschetub]

Set the pressure to 3.5

(IMG:style_emoticons/default/agree.gif) lowered fuel pressure,new floats and needle/seat valves and all we be good ,@ that fuel pressure (5-6psi ) and the floats being heavy would most likely have overcome the float valves.
Hope you get it sorted ,cheers.

[mate914]

Set the pressure to 3.5

(IMG:style_emoticons/default/agree.gif) lowered fuel pressure,new floats and needle/seat valves and all we be good ,@ that fuel pressure (5-6psi ) and the floats being heavy would most likely have overcome the float valves.
Hope you get it sorted ,cheers.

All parts changed and floats set @3.5psi. Going to start car tomorrow morning.
Thank you all for your help.

Matt

[mate914]

It runs. Have to rewire fuel pump due to removing engine relay board.
Have to fine tune carb adjustment and drive.
One glass window fuel level was slightly high and I will need to adjust.
Matt

[mate914]

This is it with car running. Why does it read so low?

[mate914]

Right side.

Fire side/left side/drivers side…..

Matt

[porschetub]

This is it with car running. Why does it read so low?

Pull the gauge and check the inlet isn't blocked or restricted,not common to have an oil filled gauge to fail reason I mentioned the above,I have the same gauge.
Is the regulator in range for the lower pressure ? i'am running the silver Holley LP and its a bit fussy when you change pressure.
Reckon you may find out on a spirited drive your pressure is low otherwise change the gauge,cheers.