5 replies to this topic

[Rallyeee]

Hi guys, just wondering if anyone else has had the same issue as me with the Gen 3s. The issue being fuel surge when at full power on hard corners. This can even happen with a nearly FULL tank, ruling out anything to do with the pump pickup/sock side of things. I've replaced the entire in-tank assembly with new parts; new mount, new filter, Deatschwerks 65C pump and also tried a Walbro. I've also replaced the O-rings in the quick-fit fuel lines.

 

From what I can tell, the culprit is the shitty design of the in-tank fuel filter. I've done tonnes of work on Gen 1s over the past 10 years or so and never had fuel surge issues because they had a simple in-line filter in the engine bay. The problem with the Gen 3's in-tank assembly is that the fuel filter housing doesn't seal particularly tight. So when the fuel level in the tank drops below the filter height at the same time as the fuel pressure increases with boost (like when cornering under full power) the fuel pressure forces fuel out of the filter housing and into the tank. This then reduces the amount of fuel getting through to the injectors and it leans out.

I haven't managed to find anyone else speaking of such fuel issues in these cars. It's a problem that probably only rears its ugly head at higher power levels and when being driven very hard but I'd imagine it could happen more easily if the fuel filter was a bit blocked or the fuel filter housing seal is very old (my issue became far less severe once I replaced these with new items). I wouldn't surprised if this has been the undiagnosed culprit for engine damage on some Gen 3s as it won't necessarily lean out so much that it noticeably cuts power. That said, I'm starting to wonder if I have a partial blockage somewhere in my fuel lines which is increasing the fuel pressure close to the pump. My next course of action is to remove the rails and hoses and check for debris and also remove the two damper valves in the engine bay.

 

Anyway, those are my thoughts, interested to know if anyone else has similar experiences.

[Rallyeee]

So no one's had any weird fuel surge issues with any Gen 3s? Does anyone here track these at all? Just trying to determine whether this is solely due to a design flaw with the in-tank setup or I have a restriction somewhere. Any of the Gen 3s I know of that have done a reasonable amount of track work have a surge tank, which would mask this problem anyway. I want to avoid a surge tank in what is predominantly a street car.

[migoreng]

Nope. Even doing 80kph slaloms with fuel light on, car is fine...

[Rallyeee]

More likely to get it on long corners under full power because the fuel pressure is higher and the injectors have time to drain the lines. That said, I think mine would do it in a slalom anyway. Have you taken it on normal circuit days too?

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[allpaw4]

I haven't noticed any surging in mine, but it's also been a while since I did any decent runs through hills and such like. And I never do hills runs with low fuel levels. Maybe one of the connectors is loose and letting air into the system? Unlikely because of positive pressure, but you never know, flow rate may override the pressure part. I might be able to give you an answer in 6 months or so, once I have tracked it, but so far no issues.

[Dav_fre]

Nothing doing doughnuts....