Saturday 17 April 2021

Still Getting Nowhere The Second

 Once again it's been some time since I reported. that's because I've still got nowhere.

The car is now running on an Omex ECU & still has pretty much the sme symptoms, but at least I can connect it to the laptop & see what's going on now.

One thing that was wrong was the Throttle Position Sensor which although I'd compared the Ford wiring diagram to the Omex one & checked it & it looked right - it was wrong, so that's fixed. Next thing, the Idle Speed Control Valve wasn't working. With the Omex I can demand it opens & closes, it made all the right noises, but the poppet valve didn't move. New one bought.

Obviously niether of these made any difference (sigh), Guy at Omex said he felt the engine was getting too much air, I had leak checked the intake side before, but again now armed with an ECU I could see into I blanked off the ISCV ports, the brake servo vacuum line & the Fuel Pressure Regulator hose that left just the 1mm hole in the butterfly it could breath through. I disconnected the injectors & the coil pack to inhibit the engine & turned it over on the starter. The Manofold Absolute Pressure sensor waent from 102kPa to 57, stopping cranking saw it take 3 seconds to come back up so there's no leaks.

I re-connected the hoses & the same happened except it took longer to get down to 57kPa as there was a larger valume of air to draw on.

I took the fuel feed pipe off the fuel rail & pumped it up with a foot pump, it went up to 40psi but no further - which is right & when I stopped pumping it went down to 30psi & stayed there, which is correct, the the Fuel Pressure Regulator is working.

I re-connected the supply hose & put a clear hose in the return side. Switched on the pumps & got a whole load of air in the fuel. I've seen this before & had convinced myself I was testing the system wrong, but here it was again & air in the fuel would explain the symptoms, I took the earth lead off the High Pressure pump & ran the low pressure one, after 15 seconds or so the pump slowed as it built pressure - but it shouldn't be able to build pressure, it pumps into the swirl pot which vents back to the tank.

Having now purged the air I re-connected the HP pump & got clean fuel on the rail.. I went under the back of the car & fitted my clear hose in a few places, there was nothing amiss, but the return line to the tank was difficult to blow down - some restriction maybe?

I've now re-wired the pumps, each has it's own relay & wireing so the ignition controls the LP pump & the ECU controls the HP pump, that way the LP pump comes on first & ensures the swirl pot is full before the HP pump starts.

Will it fix it? Almost certainly not, but it kept me amused for a day.

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