Fiat Coupe Club UK

20VT+ intermittent no start?

Posted By: Grigio

20VT+ intermittent no start? - 09/11/2017 09:55

I was in a carpark last week, when I came out to start the car it would crank, but not start, it seemed like the fuel pump was making noises that were different to normal. After checking fuses and swapping fuel pump relays it still wouldn't go. I rang my wife as she's a member of a recovery service, she came over and we rang for help. She went to get something to eat and I tried starting it again, this time it started. I left my wife at the restaurant and drove home. I had no issues for the next 4 days, until driving home from work, sitting at a set of traffic lights it stopped and wouldn't restart. I managed to back it into a vacant parking spot by cranking it over in reverse. I left if for 5 minutes, when I came back it started and I drove home. Half an hour later I went to go out again and it wouldn't start, the fuel pump again sounding other than normal. I drove my 131 to work yesterday and when I got home I replaced the coupe fuel pump, after which it wouldn't start. I tried several times during the evening but it wouldn't go, I was getting 2.5 bar oil pressure while cranking, so I guess that's a good thing in the circumstances. The battery, injector, handbrake and seatbelt lights remain lit while cranking. I tried starting it again this morning before work and it went 1st go, I went for a walk, tried it again when I got back and it started, I drove the 131 to work. It started again this afternoon when I got home from work. I've got the cables, and I've downloaded the Startrek software, I think I've managed to work out how to use it, so I'll try and get some ECU codes tomorrow.

When I first drove the car in Switzerland a few years ago it had similar issues, it would drive for a while, then die and refuse to start. The fuel pump relays and fuel pump were replaced, which seemed to have sorted the issue. I've owned the car since February and done 11k/kms relatively trouble free. It's much nicer to drive than my old 131, so I'd certainly like to have some confidence that it will keep running.
Posted By: Anonymous

Re: 20VT+ intermittent no start? - 09/11/2017 10:11

Sounds like the typical yellow connector problem.

Look for yellow plug/socket hanging between the fuse box and bonnet release handle in driver's footwell , it connects to the fuel cut-off switch, in-line on the +12v feed to fuel pump.

The contacts can become corroded or heat damaged and so go intermittent causing exactly the problems you mention. Usual solution is just to cut out the complete connector and solder the wires together, bypassing it.

Also note that both relays (injection relay and fuel pump relay) in passenger footwell above the ECU need to be working to allow the pump to prime and run.

If injection malfunction warning light is on with the non-start then could be failing crank sensor, so worth scanning for codes too, but sounds more like yellow connector.


Posted By: mr_nobut

Re: 20VT+ intermittent no start? - 09/11/2017 14:13

Had the exact same issue, it was the yellow connector. It looked ok on the outside but burnt and melted inside. Guess it’s a design fault as the connector can’t handle the supply current to the fuel pump (or somthing like that).
Cut it out and soldered wires and been fine since!!
Worth a look before replacing anything else!!
Posted By: Master_Mariner

Re: 20VT+ intermittent no start? - 09/11/2017 15:34

Graham,

Just wondering but could a failing yellow connector cause the fuel cut off to activate whilst engine running?

Ala' Gunzi's cut out problem?

It may be that Gunzi has already sorted this out on his long postings about his problem and its not the cause. Just sudden thought though...


MM
Posted By: barnacle

Re: 20VT+ intermittent no start? - 09/11/2017 17:58

Yes - the yellow connector is in the direct power feed to the pump.
Posted By: Anonymous

Re: 20VT+ intermittent no start? - 09/11/2017 18:27

Originally Posted By Master_Mariner
It may be that Gunzi has already sorted this out on his long postings about his problem and its not the cause. Just sudden thought though...


I think he said the yellow connector had already been bypassed.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 09/11/2017 21:29

Thanks for the responses, much appreciated. I'll check out the yellow connector this afternoon, as well as trying to get some codes. When it won't start, I can hear the pump shut off just after cranking, so the pump primes, and is running while cranking.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 09/11/2017 21:47

When the car was in Switzerland the engine was pulled out so some front end rust remediation could be carried out. The cam sensor, belts, crank sensor and most other sensors were replaced. It's done less than 20k/kms since then, more than 50% of that I've done this year. I've had to replace a shredded alternator belt and the MAF in that time, and an IAC valve, which probably didn't need replacing.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 10/11/2017 06:17

Well, the plot thickens. I tried reading codes with Startrack, but it didn't talk. The previous owner had bought the cables etc, but never had any luck communicating with the ECU. The laptop displayed revs, air temp, watertemp etc, but all with irrelevant values that didn't change. The blue connector has a 4 position slide switch on it. If it's relevant, what position should it be in?

I searched around under the dash between the steering column and the bonnet release and couldn't find any yellow connector. I found the yellow box with 2 plugs in it, I disconnected and reconnected them. I found the inertia switch, but the only thing yellow I found besides the box is I assume a vaccuum hose, and 2 sections of loom with yellow heatshrink on them. There is a thick loom that is P clipped to the firewall near the bonnet release it splits out into 4 connectors, all white. Does anyone have the wire colours of the yellow connector to hand, that might help?

I gave up, realised why I hate being a contortionist in car footwells trying to find wiring, and wriggled out trying to avoid hurting my back. I started the car and decided to go for a run, as I drove up the street there were noises from the boot and I realised I hadn't removed the tools after replacing the fuel pump, so I returned home, turned the car off and put my tools away. I tried again but it wouldn't start, I did notice that the pump primes, but I can't hear the relays or the pump when it stops cranking. The sound I heard previously that I thought was the pump is actually coming from the engine bay.

Cheers,

Mick.
Posted By: Countrycruising

Re: 20VT+ intermittent no start? - 10/11/2017 07:08

The wire colours you're looking for is a fairly think black and green wire, also in the same yellow connector is a thinner orange/pink looking wire, connector block is roughly 40mmx12mm.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 10/11/2017 10:02

Excellent, thank you. I'll get back under there tomorrow and see what I can find. How many wires in the block? Do they all have to be soldered to replace the block, or just the 2 mentioned?
Posted By: Grigio

Re: 20VT+ intermittent no start? - 10/11/2017 10:10

I just went out with a torch and had a look. Only 2 wires in the connector, if I disconnect it the pump doesn't prime, reconnect and it does. Definitely a white connector though. I disconnected and reconnected a few times, but the car still won't start. I'll solder it tomorrow, but I don't think it's my issue. I wish I could get some codes out of it.
Posted By: Anonymous

Re: 20VT+ intermittent no start? - 10/11/2017 10:45

Measure the voltage at the pump terminals when it's priming. Maybe you have a dodgy ground in the boot or corroded wiring to the pump. A few volts drop is expected but more than can cause problems.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 10/11/2017 10:50

I'll have to enlist my wife's help in the morning to check pump voltages, I'm sure she'll be impressed. At least she doesn't hate the coupe like she hates my 131. I was planning on giving the grounds in the engine bay a cleanup tomorrow. Where abouts in the boot is the ground?

Cheers,

Mick.
Posted By: barnacle

Re: 20VT+ intermittent no start? - 10/11/2017 13:08

Re the codes: if the adaptor has a switch on it it's possibly/probably incompatible with the Coupe and the software. Startrek needs an adaptor with an FTDI chip in it, so it might be worth a look at the device manager to see what it thinks it is.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 10/11/2017 21:21

I've downloaded the FTDI drivers from a link in another Startrek thread. The blue cable has VAGKKL+FIATECUSCAN written on it, the far left position on the slide switch says KKL/engine, so that's what I used. I'm just about to go and solder the yellow plug wiring. From this thread it appears others with a 2000 20VT plus have had exactly the same issues that I'm having trying to get codes. http://www.fiatcoupeclub.org/forum/ubbth...rue#Post1464284
I'm using a 64bit windows 7 laptop, I'm going to give an old XP clunker a run and see if I have better luck.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 10/11/2017 22:06

Ok, a win, of sorts. I reloaded the FTDI drivers, cancelled windows updating to it's own drivers and got some codes. Ignition on, engine wouldn't start.

(128) Pressure sensor below minimum.
(64) Crank sensor open circuit.
(64) Crank sensor signal implausible

So a bit of work ahead of me, but at least the cam angle sensor doesn't get a mention. Thanks for the help, this forum is an invaluable resource.

Cheers,

Mick
Posted By: Anonymous

Re: 20VT+ intermittent no start? - 10/11/2017 22:37

Crank sensor is not too bad to change, just below the starter motor on back of engine.

I think the pressure sensor is the atmospheric pressure sensor on top of firewall behind the intake manifold, may just be a dodgy connector but the sensor itself can fail and will normally result in reduced boost.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 11/11/2017 11:38

I disconnected the battery again while I got under the car to see what I'm up against. I couldn't see the sensor, but I should be able to remove and refit it by feel, access to where the connector joins the loom looks to be more of a pain though. When I was done I tried starting it again, it fired 1st go, so I hooked up the laptop, everything as it should be and no errors. I've ordered a CAS and I'll drive my 131 until I can replace it.
Posted By: Grigio

Re: 20VT+ intermittent no start? - 23/11/2017 20:55

Crank sensor turned up 4 days ago, a genuine Bosch jobby, rather than the generic one I removed, I fitted it and the car started 1st go. I've been driving around without issue, until yesterday. After stopping at the chemist for 10 minutes, I reversed out and the engine died as I changed to 1st, I didn't stall it. It started again straight away, but it is a bit disconcerting. I have noticed that at idle it occasionally misses a beat but picks up again, it has done this prior to replacing the CAS.
Posted By: Anonymous

Re: 20VT+ intermittent no start? - 23/11/2017 21:18

Assuming you cleared the old error codes after replacing the sensor, are there are new ones now?
Posted By: Grigio

Re: 20VT+ intermittent no start? - 24/11/2017 03:15

Checked codes this afternoon after work.

(128) Pressure sensor below minimum

This error had come up previously as well as the crank sensor, the battery was disconnected for 3 days while I waited for parts, there were no errors after I fitted the new CAS.

Weather is warm, and I noticed the idle drop and pick back up when the radiator fan came on. I hadn't noticed the fan previously as I'm not usually sitting beside the car with the bonnet open, although I seem to be doing it more often.

In the original post I didn't mention that as I was backing into a parking spot by cranking on the starter in reverse I clipped a woman's car that had moved out of my lane into the centre lane. Not much damage to her car, cost me $200, I had a quote for mine yesterday, $1000.
Posted By: Anonymous

Re: 20VT+ intermittent no start? - 24/11/2017 10:00

The pressure sensor problem shouldn't cause it to cut out, but a crank sensor problem would.

Did the old crank sensor o-ring come out with the sensor? If it didn't and you fitted the new one with the new o-ring then it won't be sitting flat as it should be so may not be reading 100% correctly. Strange it didn't flag an error if that was the issue though.

You could also try unplugging the pressure sensor on the bulkhead.

Posted By: Grigio

Re: 20VT+ intermittent no start? - 25/11/2017 15:32

The old O-ring came out with the sensor, and I made sure the new sensor was seated correctly before fitting the bolt. I did notice though, when I was finished and I moved the car in to the carport, the revs dropped to about 500 and picked up again to around 700-750 where it usually idles. So I tried replicating it, if I hold the revs at about 1500 and take my foot off the accelerator, the revs drop to around 500 before it recovers to normal idle. I'm telling myself this is a separate issue and I've fixed the CAS problem.
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