Vapor Lock 1.8 '74 L-Jetronic

[coconut 321]

All is not well with 914's here in the islands, this "endless summer" is playing havoc with my F.I. system. Daytime temps in the 80's+ prompted me to consider Jim Thorusen's "Fuel Pump Relocation" article, but first I decided to check heat sources acting on the fuel system with an infra-red temp sensor (Raytek mini t emp mt4). With the engine fully warmed up at idle I found temps as follows: metal fuel rail between #3cyl &#4cyl. injectors- 132`, plastic fuel feed line- 124`, plastic fuel return line- 130`. Now to pinpoint the heat source- passenger side heat exchanger J-tube- 228`, heater flapper box- 285`, and metal flex hose-to-heater in car-214`.

In addition I checked the plastic fuel filter- 153` one end, 130` other end, fuel "Y"-130`. The fuel pump had been relocated on the firewall near the fuel lines to & from the tank and is insulated with a thick foam rubber wrap which I found to be at 147` surface temp.

Working with this info I have removed the metal flex heater hose (who needs heat here anyway?) and capped the flapper box, wrapped the fuel filter with non-combustable insulation held with S.S. clamps and located away from the greatest heat source.

So far my fuel supply & return lines temps have dropped to 95`-105`, and my fuel rail temps are 110`-115` idleing, fully warm engine. The rail temps do raise 3-5 min. after shutdown to 120`- 125`. This all may be helpful to others, however my quest for cooler fuel continues. Here's hoping I don't have to locate the fuel pump to the trunk. Al

[rfoulds]

If you are in Hawaii, remove heat exchangers and run headers!!

Seriously, thanks for the info, this is a problem I constantly battle. I find just running with a half tank or better makes a difference.