PEM issue, I think not, wiring or pump...

[TDIvolvo]

About 4-5 years ago this forum helped me with my 2005 2.4 T5 V70 and a hesitation, stalling, no start problem which lasted for a couple of weeks until one day she would not start. PEM. Anyway, Evolve breakers and a second hand PEM (an internally installed one in good looking condition v's my titanic wreckage looking PEM) and she's been fine ever since.

Well, until the 21st of Dec last year, going along a farm road at about tick-over and I could feel an occasional lumpiness. Stopped to do something and she idled fine for maybe 2 minutes then started to die, fluctuating revs, surging etc. very typical fuel starvation. I knew exactly what it was as it happened, then she died. Continued doing what I was doing then went to restart her but she just spun over, luckily I was on a hill so rolled down the hill and into the yard, did some checks, first was to check fuel in the rail, nothing, just a hiss of air as I depressed the Schrader valve - quickly checked the fuse, fine, went to the PEM, wiggled the wiring, gave it a thump with my hand, still would not start.

I waited for maybe 30 minutes then decided to give it a go again, burst into life, reved up, all OK. Out in the sticks so pull out onto main road and gave her a load of throttle for a good pull up to 60mph, 2nd & 3rd and pulls like the best T5. Drove about for 15mins with only 1 hiccup and it was like for a split second she just lost fuel again, but doing 50-60mph it just manifested as a jolt when the fuel kicked back in.

Being just before Christmas, busy and not in the mood and we have other cars I just parked her.

I ordered a new PEM that night, at £50 delivered I wasn't even going to diagnose it yet, worst case it becomes a spare.

Friday night past I used her for the first time since, just to see what the situation was, started her up, about -5 so let her idle to warm so I could get the blinking doors to open (went in via boot), and she ran for 10-12minutes before dying, restarted immediately, and I went out in her, ran OK, cut out once as I approached traffic lights (always seems to be at low speeds/idle - I have a theory on this) but restarted.

Saturday morning I put her up on my ramp and had a look around, PEM actually looked in OK nick, pulled the connector and plugged in the new one just hanging there, lowered her down a bit and turned the key, starts and runs fine. Raise her back up while still running to remove old PEM, I am standing right under the tank and I can hear the fuel pump running, then it's not, OK, maybe the rail pressure is just high enough and the pump has slowed, 5-6 seconds later the engine starts to struggle, pump still not running. Smack the tank for good measure, wiggle the PEM connector, pump still not running, 15-20 seconds after the pump switched off she dies.

So, it is not the PEM. Try to restart her but nothing, same as what she did last year. Rail full of air. I get a known working FPS and plug it in just to force a low pressure signal just in case it is the sensor, try again, nothing. Undo that test and go back under the car. Plug in the old PEM, just in case, nothing. Decide it's probably time to pull the pump but one last check before I go for it is to pull the connector off the PEM, and using a 0.5mm drill bit I manually "drill" each connector to scuff it up and clean it - I also smacked the tank.

Lower the car, turn the key and she revs up like a champ.

I am fairly sure it is either corrosion in the connector or the pump.

Simplest thing is to rule out the connector.

So my plan was to relocate the PEM into the car anyway so I will disconnect the loom from the fuel line, pull the loom up into the cabin through the fuel pump access plate, cut off the PEM connector, trim the socket section off the PEM to cleanly expose the 5 terminals and I am going to solder the loom directly to the PEM, heat shrink it and all give that a go. If the issue goes I will probably just leave it be but if that proves to be solved I might get a new 5 pole connector, install that onto the loom, and using a short length of wire put a connector onto the PEM, and do the same for the spare I have here, thus, if I have a PEM issue in the future I can simply swap them round by plugging in the spare - that also makes it more roadside repairable.

This also gives me easy access to the wiring for metering, I think I will connect a high speed volt meter to the pump output and lead it up to the drivers side so I can watch the voltage as I drive

So if it is not that then pump will need to come out, I have a pump here from a 2.4 - I wonder if it is the same.

From someone who has had a fuel pump in one of these fail, do any of these symptoms match fuel pump failure you had? My experience of pump failing has been a lot more clear cut, high pitched whine with no fuel pressure, or just dead etc. if this pump is failing then it seems not to have given up the ghost, I know that electrical motors can behave like this, warm up and die, then when they cool they will run again but it doesn't really make much sense.

I mentioned I had a theory above, it always dies fully from idle or low speed, now the PEM varies the voltage to vary pump speed an therefore pressure in the rail, idle and low speeds will therefore be low voltage situations, so the dodgy connector may have a high impedance which would have a bigger impact on say 3v at idle pumping than on 12V at motorway speeds pumping. Therefore it backs up my thought process here.

[TDIvolvo]

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