Carbed Fuel Delivery Issue

[Ponyryd]

In that case I'd start by pulling the hood and going for a drive. Alternately you could try grabbing some bags of ice and tucking them around the carb, then going for a good drive. If the ice is still there when the engine is hot and it normally acts up, you know your problem is in the carb bowls. In which case you can get a spacer as mentioned earlier, or you can make up some sort of insulation system to help isolate the carb from the engine better.

[Stephen06GT]

Can you fab up some sort of heat shield to isolate the bowls from the heat source?

Edit: Should have read Ponyrd's post a little more carefully.

[ZR]

I'm also a fan of heat being your most likely culprit. More common in carb'd rides that run an electric fan. Old school mondo flex fan not only pulls tons of air through the rad but also keeps lots of air running up past the carb n helping it to keep it's cool.
Ice + hood off idea seems solid to me as well.

[TurboFox]

Toss in a phenolic spacer because it cheap and take it from there

[Ponyryd]

I'm also a fan of heat being your most likely culprit. More common in carb'd rides that run an electric fan. Old school mondo flex fan not only pulls tons of air through the rad but also keeps lots of air running up past the carb n helping it to keep it's cool.

Agreed, also the bay has been smoothed so you're losing more areas of cool air underhood. Also the fan you have doesn't look very big, and the shroud doesn't cover the whole rad.

[tulowd]

Agreed, also the bay has been smoothed so you're losing more areas of cool air underhood. Also the fan you have doesn't look very big, and the shroud doesn't cover the whole rad.

2200cfm Flexalite

hood has rear cowl openings for air flow from scoop and thru rad - hood doesn't bulge or grow at highway speeds, so airflow thru there is decent.
Only two aero changes to the car have been the brake ducts and the Mach 1 chin spoiler.

The heat issue plagued me last summer as well; but I was too stupid to check the float bowl temps, duhhhhh!! lol

[Scott]

If the problem is the fuel being too hot in the fuel bows there could be two causes. Firstly as other have pointed out radiated heat from the engine. Secondly rising fuel heat in general caused by heat generated by your fuel pump in the return style system. This is a common problem with multiple pumps in the S197 platform. Solution there is to use a controller that stages the 2nd / 3rd pumps on based on boost. Fore's FC3 controller is an example when used with a Hobs switch.

From you pictures you are feeding both bowls on your carb from the regulator to the passenger side bowls. I would expect if you ran returns from both bowls from the driver's side back to the regulator your fuel temperature would go down as fuel would not be in the bowls long enough to absorb heat from the engine. Aeromotive makes a 4-Port Carbureted Bypass Regulator, part number A1000. To see if this is the issue I guess you could put a couple of Y-Blocks in with your existing regulator. Basically fuel would not dead head in the bowls and there would be a continual flow through the fuel system. Paul, hope this makes sense? If not just shoot me a PM.

[tulowd]

If the problem is the fuel being too hot in the fuel bows there could be two causes. Firstly as other have pointed out radiated heat from the engine. Secondly rising fuel heat in general caused by heat generated by your fuel pump in the return style system. This is a common problem with multiple pumps in the S197 platform. Solution there is to use a controller that stages the 2nd / 3rd pumps on based on boost. Fore's FC3 controller is an example when used with a Hobs switch.

From you pictures you are feeding both bowls on your carb from the regulator to the passenger side bowls. I would expect if you ran returns from both bowls from the driver's side back to the regulator your fuel temperature would go down as fuel would not be in the bowls long enough to absorb heat from the engine. Aeromotive makes a 4-Port Carbureted Bypass Regulator, part number A1000. To see if this is the issue I guess you could put a couple of Y-Blocks in with your existing regulator. Basically fuel would not dead head in the bowls and there would be a continual flow through the fuel system. Paul, hope this makes sense? If not just shoot me a PM.

Thx Scott: That does make sense - in effect using the bowls as part of a fuel log / return portion as opposed to the dead head current setup. I think some of the new EFI rails run the return from the back not the front in a similar arrangement.

I am convinced the heat is from the motor not the pumps, as yesterday the new Edelbrock pump was still cool when the pressure started dropping and the bowls were hot. The fuel lines are never hot, just warm to the touch.

Going to try a heat shield and phenolic spacer first; then figure out if I have a secondary issue with the return feed into the tank aerating the fuel.

[tulowd]

After installing the heat shield and the phenolic spacer, it is better, but I found that both -8AN fuel lines are really hot front to back, including the disconnected return line. Pump is warm; tank is cool.
Will have to look at where the fuel lines are both run, as they were pulled off the car recently to drop the tank. Perhaps a heat shield is in order - the lines run close to the passenger side muffler for about a foot; everywhere else they are on the other side of the frame rails. Hmmmmmmmm

[Ponyryd]

How close to the muffler? any less than 2" is too close IMO.