Carbed Fuel Delivery Issue

[tulowd]

Found an old catalytic converter heatshield from my F150; went to PI and picked up some of that heat wrap.
Hopefully get the stuff installed in the morning.

I think its about 4 inches away, but my feeling is being braided line means it picks up heat from the frame rail and floor pan nearby.

Thx for everyone's input - will report back.

[tulowd]

Did some more needless work, swapped out the pump, rerouted the fuel lines, sleeved them and made a heat shield and finally got rid of the regulator it still ran like crap.
Ran pump with return regulator for almost 2 hrs on Sat morning, cool as a cucumber.
A sponsor pm'd me and said my build has a vacuum leak from having a breather and pcv valve hooked up.
Ran it disconnected, and returned the carb to exactly how it was delivered from Pro Systems. Car ran great, lots more jam; smoother idle and throttle tip in. Also installed carb heat shield and phenolic spacer and got a new air cleaner base which unshrouded the carb and put the filter smack into the cold airstream from the hoodscoop. Bowls and lines are way cooler than before, so this is a good thing regardless.

AFR looked good - until it warmed up and went lean again! BTW - idle speed and AFR down low stay the same under both conditions. Oil pressure needle moves a little while driving too when its real hot and lean.
Finally took the intake off, hoping to find a bad intake gasket - no such luck. Did find the brake booster take off fitting that had been plugged was not as tight as it should have been.


Hopefully once that is sealed up and everything is back together it will be the end of this little challenge.
I'll report back once I get it back together later this week. Thx for everyone's help.

[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.

Gave you some bad advise in the second paragraph, not sure what I was smoking, but it must have been good. You definitely do NOT need a 4-Port Bypass Regulator. The 2-port one you have is all that is needed. Simply feed both in ports of the carb form a Y-Fitting and route the carb out ports from each bowl to the 2-Port regulator. Sorry about that!

[tulowd]

Gave you some bad advise in the second paragraph, not sure what I was smoking, but it must have been good. You definitely do NOT need a 4-Port Bypass Regulator. The 2-port one you have is all that is needed. Simply feed both in ports of the carb form a Y-Fitting and route the carb out ports from each bowl to the 2-Port regulator. Sorry about that!

lol...you get a gold star for an excellent idea - the execution is my job. Pretty sure all that is needed is the float bowls modded and some more line. Basically carb would go before the regulator as part of the regulated flow; kinda like the fuel logs that run the regulator at the very end / last component before the return.

[Ponyryd]

Were the intake gaskets crushed at the bottom? See it often that the lower portion of the intake isn't sealing causing a vacuum leak inside the valley.

[tulowd]

Were the intake gaskets crushed at the bottom? See it often that the lower portion of the intake isn't sealing causing a vacuum leak inside the valley.

nope, they looked perfect. Hope it was really that NPT fitting....fingers crossed

[Scott]

lol...you get a gold star for an excellent idea - the execution is my job. Pretty sure all that is needed is the float bowls modded and some more line. Basically carb would go before the regulator as part of the regulated flow; kinda like the fuel logs that run the regulator at the very end / last component before the return.

Exactly!

[tulowd]

drivers side intake surface

passenger side intake surface

#1 cylinder intake valve is golden yellow and clean; other 7 valves have some crud buildup. Means coolant was leaking slighting into that cylinder. Also appears the gaskets were not sealing around several ports.
Motor had 1000 km when fresh in Sep 2010; then sat in unheated garage until it ran again in May 2013.
Any comments ?

[ZR]

Regardless, intake needed to come off for clean up and reseal.

[Ponyryd]

What kind of gaskets are you using? also, was the intake new or used when it went on the engine? same question for heads. Sitting in the cold for 3 years should not effect the gaskets.
You may want to check how that intake fit on the heads with no gaskets while it's off.