Troubleshooting fuel system components

The Oily Bits S2 Specific Topics
1

Had a trackday at Blyton cut short today, seems fuel related but can’t be 100% yet.

Car ran like a dream up until lunch time, it was on fumes when the chequered flag came out so I drove it the 20mins or so to get fuel (Jet 97 RON… the best option really for Blyton).

Car drove fine on the way back to the track, and retrospectively checking the logs show that the lambda was meeting target and everything was happy. Parked it up in the pits for a few mins, then went out for another session. Car idled in the pitlane for a bit while we waited for a red flag to end, logs showed fine lambda for that short time.

Almost as soon as we went out on track, the car started heavily missing above 3k RPM, sounded like traction or launch control kicking in (neither active on the logs). Car stuttered around the outlap and brought it back in, expecting a hose to be off or something - but nothing was obviously amiss.

Lambda at idle was reading 1.40 (target of 1.0) so running very lean. Driving the car and the best I could get was around 1.20 on part throttle/cruise. Any sudden demand for fuel and the car would violently stutter, but if you were very gently on the throttle you could creep it open and get revs into the higher ranges, but still running far too lean.

I tried letting it cool off, tried a few road miles to let it clear its throat - no dice. Eventually I limped it home, kept speed and RPM low and it got me back OK.

Based on the fact it ran so well up to fuel, I’m (perhaps unfairly) blaming the fuel - so will be looking to lift the pump and injectors, but other than checking for obvious crud I don’t really know what to look for. I’ll speak to Spitfire Gaz and hopefully he can help me bench test the pump, and I guess there are places that can test injectors - but any DIY tests would be welcome in the meantime.

I’ll also drain the Jet fuel and refill with something else.

Any other suggestions?

2

one easy check is fuel pressure

3

Cheers Dave, been looking into some fuel rail adapters to help me stick an analogue gauge on. Seems the 2zz doesn’t have an electronic sensor for fuel pressure :frowning:

Think tomorrow I’m going to drain the tank to start with - see what comes out and then stick 20l of fresh vpower in it and see what happens. I’ll disconnect the fuel rail to do this and just prime the pump a few (thousand) times to drain it, can give the injectors a once over whilst I’m there. If that’s not a magic fix, I’ll get the pressure checked at the rail and/or take the pump out.

4

Gaz @ Spitfire has given me some metrics to help judge the performance of the pump - just need to setup some piping into a bucket and I should be able to trigger the pump from my ECU without messing around with wiring etc.

In the meantime I’ve taken my chargecooler off for access, given my injectors the visual once over - nothing obvious. I was hoping to squirt them into some clear bottles just to make sure one of them wasn’t obviously blocked or poorly but I don’t think that’s going to happen without extending the wiring. Seems a bit extreme, but larger capacity injectors were next on my roadmap anyway so might have to just upgrade them to rule them out :unamused: :mrgreen:

Hopefully I can get the pump performance benchmarked next week, tank drained and get some fresh vpower in. If the pump is doing its job, I’ll see if the fresh fuel magically fixes everything. If not, injectors will be swapped (they might get swapped regardless).