Fuel return line MY86
06-27-2021, 08:30 AM
#1
Rennlist Member
Thread Starter
Fuel return line MY86
The fuel return line on my 86.5 is two pieces plus a bracket in between. PET shows a one piece 440mm line for this MY, but looking at '87 parts in PET, it looks like a two piece arrangement, so my conjecture is that this is another case of point-five 86-87 hybridization. But as usual the PET illustrations leave something to be desired and I can't tell for sure if this is the case. My problem is that I need the short line that goes from the FPR to the bracket, which I think has to be preformed. I have tried PTFE-lined Goodyear line, but it kinks, not much, but maybe just enough to cause what Porken noted as an increase in pressure which can lead to a too-rich situation and a rough idle - symptoms I've been chasing for a while. Any help appreciated!
06-27-2021, 09:32 AM
#2
Rennlist Member
If there is a kink in the line it will create a resistance to flow- if this happens to the extent it can, the fuel pressure regulator will open up to compensate as it tries to keep the fuel rail at a specific pressure.
Any fuel hose has a permissible bending radius, as it changes direction the internal cross section turns ovaloid and at some point it distorts and kinks- not good! Once a hose is kinked the chances of eventual failure rise dramatically and must be avoided at all costs. As I am aware the likes of Roger and GB will have solutions for your problem.
Under normal circumstances this section of line has very little pressure in it but if the kink is serious enough then the pressure could raise to whatever it is in the fuel rail- another reason to avoid such even though the hose in perfect condition will be well more than capable of withstanding such pressure.
Any fuel hose has a permissible bending radius, as it changes direction the internal cross section turns ovaloid and at some point it distorts and kinks- not good! Once a hose is kinked the chances of eventual failure rise dramatically and must be avoided at all costs. As I am aware the likes of Roger and GB will have solutions for your problem.
Under normal circumstances this section of line has very little pressure in it but if the kink is serious enough then the pressure could raise to whatever it is in the fuel rail- another reason to avoid such even though the hose in perfect condition will be well more than capable of withstanding such pressure.
06-27-2021, 04:27 PM
#3
Former Vendor
The fuel return line on my 86.5 is two pieces plus a bracket in between. PET shows a one piece 440mm line for this MY, but looking at '87 parts in PET, it looks like a two piece arrangement, so my conjecture is that this is another case of point-five 86-87 hybridization. But as usual the PET illustrations leave something to be desired and I can't tell for sure if this is the case. My problem is that I need the short line that goes from the FPR to the bracket, which I think has to be preformed. I have tried PTFE-lined Goodyear line, but it kinks, not much, but maybe just enough to cause what Porken noted as an increase in pressure which can lead to a too-rich situation and a rough idle - symptoms I've been chasing for a while. Any help appreciated!
(You mentioned Porken, so I wondered if you had changed chips/regulator style.)
06-27-2021, 05:23 PM
#4
Rennlist Member
Thread Starter
No, original 86 regulator, and I think, and although I can neither remember nor find the quote (f&g#!d and Chrome history ain't helping) I believe Ken was talking about a stock installation. Any recommendations, Greg?
06-27-2021, 05:26 PM
#5
Rennlist Member
Thread Starter
Any fuel hose has a permissible bending radius, as it changes direction the internal cross section turns ovaloid and at some point it distorts and kinks- not good! Once a hose is kinked the chances of eventual failure rise dramatically and must be avoided at all costs. As I am aware the likes of Roger and GB will have solutions for your problem.