nick_968

Since I began with my 3.0 turbo build I have always had issues with my hot start.

I have been round the houses with this and have managed to get round the issue recently with some tweaks to the hot start fuel cranking map (standalone ECU).

The issue still bugs me though. I have the Lindsey fuel rail setup with the Fuelab adjustable pressure regulator, and with the gauge fitted to the regulator you can watch the pressure drop off within about 5 mins to zero. I am convinced this is the cause of the hot start issues as all other alternatives have been checked, tested and replaced. As you can see the pressure drop off it is almost certainly the cause.

Does anyone else have this Fuelab regulator and experience the same issues as I would have thought there are quite a few people running these? Fuelab say it is normal for this type of regulator to drop pressure after shutdown as it is a metal to metal seat and just the way it is designed.

As I now have AN fuel lines is there a better regulator or a way to get back to using a Bosch style regulator but still keep my AN lines? Otherwise I have to go back to a factory fuel rail and install factory lines again to solve this problem and I do prefer having a billet rail.

Cyberpunky

I am using a CEP custom fuel rail with Bosch FPR and AN fittings. Device is called a saddle adaptor. Someone here posted a link, I think in the CEP fuel rail thread.




My mechanic sourced the suitable adptors to go from the std factory threads to AN on rail

rlm328

I am using an Aeromotive regulator which is a similar design. Having said that I have had no problems with this style regulator. How old is your fuel pump and could the problem lie with the fuel pump check valve?

numbskull

My car has the same setup, remote fuelab & LR fuel rail. I did have the Marren damper recently replaced due to leaks. After shutdown it takes a lot longer than 5 minutes for fuel pressure gauge to hit 0. How old is your fuel pump and what fp ?

odonnell

Fuel pump check valve at the fuel pump (pressurized side) may be bad, or not working correctly at the pressure you set. Have you eliminated the possibility of injectors leaking into the chamber(s)? That may not be noticeable for cold starts cause it's already evaporated.

nick_968

Thanks, that is the kind of thing I was looking for.

nick_968

The fuel pump is not that old and Bosch 044. Seems to work ok. Fuel pressure is 3 bar. I did also fit an additional check valve on the flow line into the AN lines at the wheel arch end of the fuel lines. So there should be no way it is the check valve on the flow line as there are now 2. This did slow the pressure drop a bit but not enough. How long does it take for yours to return to zero?

nick_968

Injectors are new injector dynamics injectors. It had the same symptoms with the old injectors which were also not that old. As above I have added in an additional check valve close to the engine end to rule out the check valve on the pump.

My thoughts are that maybe the Fuelab regulator is not sealing up as well as it would have when it was new and is losing pressure on the return line faster than it should?

nick_968

Another question - how would I know if the damper was going bad - assume any leak would be visible?

I have also just replaced all my fuel lines for pro gold ptfe hose to get rid of the fuel smell you get with the cheaper rubber base lines that sweat fuel vapour. I have not yet fitted them as only got the made yesterday but not expecting it to make much difference.

numbskull

If you also have the marren on the fuel rail mine was weeping a bit through the rubber bladder. If you email them they do lifetime free repair, just pay ship both ways. Yeah, the pfte is the way to go. The rubber hoses weep after 3-4 years and need replacement. I found a great kit at Pegasus where you can get pfte hose and fittings that actually seal well for years. Theres a box of so many AN fittings new that did not seal with different rubber hoses in my garage, stainless, nylon. The earls fittings worked pretty good but other cheaper ones are not worth it because they leak when fastening to JIC.

Are you sure all the current fittings are not weeping enough to cause quicker pressure loss ? Initially I had so many issues with AN until finding good ones that seal so you could smell raw fuel at the fittings it made me want to go back to clamps again.

nick_968

Ordered this yesterday, lets see if it does the job...

http://www.radiumauto.com/Fuel-Press...ator-P229.aspx

Tom M'Guinn

I'd try jump starting the fuel pump to bring the fuel pressure back up, and verify that the pressure really is causing your issue. It very well may be the issue, but why not confirm. Start-up maps on the stand-alone, fuel type and temps, plug ranges, etc. all seem like possibilities in theory anyway...

nick_968

Tom the pressure comes up fine as soon as I turn the key and the pump primes for 5 secs. I have a gauge on the FPR so I can see it happening live.

Tom M'Guinn

I'm not following you... Why do you think the hot start issue is related to fuel pressure if you can see that you have good pressure? I could follow if you thought the injectors were leaking into the cylinders when you shut down, but you said you have new injectors and don't think that's it. Or are you saying you don't want to wait the 5 seconds for pressure to build for the motor to start?

For what it's worth, I have 25k miles or so on my motor with a stock rail, damper, 3 Bar Bosch regulator and 044 pump...

nick_968

Tom the problem is that when I turn the key off the pressure starts to drop and this is a design fault of the fuelab regulator although it sounds like mine is dropping off faster than some others who have the same setup. So I may also have some weakness in my lines. The rubber braided lines seep fuel vapour anyway so I have swapped to higher spec PTFE lines which are better for fuel although not installed them yet. At the same time I do this I will install the factory FPR which should cure the drop in pressure once the ignition is off. I think this is allowing some fuel evapouration and/ or letting the injectors get too hot causing heat soak issues. With the FPR the pressure will remain high in the rail and temps should stay cooler. If I restart the car within 10 secs there is no hot start issue it only happens when the car has been left for a couple of minutes or more and gets worse the longer it sits. Having replaced pretty much everything else this is the last mechanical option I have left and it also follows the guidance on Clarks Garage about hot start issues being related to pressure drop ofter shutdown, which a regular FPR is not supposed to do. None of my system is currently factory as I also have the Lindsey rail.