Yep Beags. Hind sight is 20/20. My fuel lines are in the stock TBI location. Still using the feed and return up to the fuel filter where the Workhorse lines (braided) take over and run in the stock location all the way to the back of the engine over the trans bellhousing. The issue in my case is my sheer stupid level of trust I put in my nitwit exhaust guy to execute my plan. The guy totally ran it tight to the frame which just amplified the problem. There is no stinking room to really run the exhaust along the pass side of the trans/t-case and over the t-case crossmember and NOT build heat into the fuel system. The frame rail is a great shape to trap and retain the heat making it that much worse. Had I had my guy run the pass side pipe under the engine like the stock TBI trucks or Larry's burb (see his pics in my thread) and then run it down the drivers side rail I probably never would have had a problem.
If you got heat shielding use it. I will say this I've found some consistency to my problem over the Utah trip and the most recent one. For mine to act up ambient temp isn't as critical as the sustained amount of time I've driven to pump heat into the system. Yes in Moab I had 100-degree temps, but it still took at least 3 hours of driving before the problem occured. Same was said for driving from the Moki Dugway to Hovenweep, 2 1/2 hours of driving and it quit. Friday from home to where we hit the trail was 3 1/2 hours with a stop for breakfast and fuel along the way. We aired down and 20 minutes up the trail it stalled. Saturday it was from camp at Mirror lake to Taylor park for a splash of fuel/supplies and all the way up Reno Creek to the cabin in the picture which was easily 3 hours with most of that cruising up hill in low range at 5 mph with temps in the mid 70's and falling the higher we went up. Sunday we had 5 hours on Pearl pass in low range for at least 30 of the 37-mile trail, we pulled into Aspen topped off again and blitzed up Independence pass at 20mph as that's the speed limit most of the way up. It conked out a mile from the top almost 6 1/2 to 7 hours after we broke camp. Temps at where it stopped was back into the 60's at 11,000ft of elevation.
So it's not just the outside temp. Higher temps seem to speed up the process but it's a cumulative buildup of heat that can affect the system in two ways. One the returned fuel to the tank being pre-heated is just adding heat to the tank and therefore the pump. Keep cycling that fuel over and over again and pretty soon the pump overheats and quits. The second problem is if your exhaust is Stevie Wonder close like mine is, that radiant heat coming off of the pipe near the lines and trapped by the frame rail you can still actually get the fuel to boil in the line even under pressure. You'll know if you put a fuel pressure gauge on the test port and hit the dump valve you'll see more air than fuel come out. I didn't have a gauge with me this weekend so I pulled a dumb move to press the Shrader valve with a small screwdriver and catch the little bit of fuel with a paper towel. I was still dumping a ton of air out of the system 10 minutes after the engine shutting off.
I'll be taking an approach to model my new exhaust similar to the TBI setup with it crossing over under the engine/trans and running down the driver's side rail.
