jeeptester

Vapor lock possible in 4.8 2008 TJ Jeep. I have the wix corvette filter regulator setup with the oem 1997 TJ in tank pump. On a hot day if sitting idle will starve for gas smells lean and die, after it cools it runs fine. I used a temp probe and the fuel line leaving the regulator is 140 deg F on a 95 deg day. I wrapped the exhaust next to the filter. The above temps are after I did the wrap. I also installed a small alu shield over the regulator. Does this sound like Ive done enough or do I need to think about re-routing the exhaust???


The above pic shows were it is the exhaust is about two inches away and exits the rear durring build

below is after I wrapped it

plastic wire tie is temp

Bo185

The shield over the filter/reg needs a stand off to give air space. Also take a fuel pressure reading when if it gets hot and has idle problems.

jeeptester

The elec supply is run behind the shield so there is about 1/2 of space.
Well I did another test and it didnt die but engine temps got to 215 and under medium accelartion up hill it stumbled bad and almost died, I coasted to a stop and let it cool down at idle to 203 and drove normal after and it never cut out again. (I drove easy and never let it get over 207)(Idk if its related or not)

It seems if I run on a humid day 70mph or more temps will go from 201 to 215 if it gets to 215 and it stops for a moment it will stumble like low pressure. Im thinking vapor lock but just cant seem to find were its doing it. But Im also wondering I know the 215 temp is not really high but I dont think it should go up 14 deg just because running 75mph vers 65

Im thinking temp issue possible are
1. poor flow inlet , outlet too small at rad
2. rad too small , rad fab shop said this rad is good for a v8 but idk
3. poor air flow idk the cfm of the fan i have so its possible its too low
4. air flow poor because shroud is flat design

Vapor lock issue , I just dont know on that, ideas????

Thanks
Lowell

JIMB

iTrader: (2)

My first TJ LS swap was a 4.8. I didn't have any vapor lock problem. Ran great.

Ran the stock 4 cylinder in tank pump directly to to fuel rail because the stock wrangler pump is regulated for pressure right in the tank. It's part of that assembly right above the fuel pump. Worked good no starvation problems. The tank vent I looped a rubber fuel line up to the filler area and put a roll over valve in the end of the hose.

Could it be if you are running the stock intank pump/regulator you are over regulating it by using the Corvette filter regulator?

I forget how I mated the stock fuel to the -6 coupling on the fuel rail.

Doesn't the fuel line run up the driver side frame? Exhaust down the passenger side frame rail? My fuel line is no where close to the exhaust.

I ran a 4.0 HD radiator and shroud. Mechanical 4.8 fan. Always ran cool.

jeeptester

I removed the regulator because I was told the 97 tj regulator is too low psi, I was also told the 01 or higher can
Good idea about the vent tube I just plugged it
I have dual exhaust out both sides
There is no room for a mech fan.

I did finally find the cfm of the fan Im using its a 15 inch 1000 cfm I have ordered a two speed 2400 cfm 16 inch
I will see if that helps, only thing is idk were or if vapor lock is causing it, but it does not happen if below 209 deg

LS102ws6

sounds more of a heat related issue.

JIMB

iTrader: (2)

My 4.8 TJ swap was a 98 4 cylinder. Don't know if 97 and 98 fuel pump regulator are the same but mine worked great.

Currently I have the same 98 TJ with an LS6/4l60e. 2600 cfm single Spal fan. Novak Adapters alum radiator. Cools very nicely.

If you plugged the tank vent line it would be causing a vaccum in the tank. The TJ gas cap is not ventilated unless you ventilated it somehow.