Non-start advice please
 

The ZT (120) cut out on the ring road yesterday and had to be recovered.

I wasn't driving it then, but I have it home now. It still won't start.

I've checked:

• No codes present, using a cheap OBD2 tester.
• Spark on plugs from both coil packs.
• Air filter good, and engine will briefly run on easy start squirted in the intake.
• When engine runs on easy start, tacho works.
• I fitted a foc to the fuel filter a year ago, when I had fuel gauge probs.
• The fuel pump can be heard (priming I assume)

Am I right in thinking that the spark shows Cam Position Sensor is working and tacho indicates Crankshaft Position Sensor is working?

My conclusion is fuel supply. Is there a troubleshooting how to on this? I'm unsure about the filter seals. Is the lipped seal external to the filter critical to the system working eg does the fuel tank pressurise? Or just the O ring seal internal to the filter? I also am unsure where to take pressure readings from.

Hi Michael,

The wise words in the MG Rover manual rule out your camshaft sensor (it's required only for starting, not for running).

The fuel tank isn't pressurised.

Check that the pump runs for two seconds when the ignition is first turned on. Next check that it runs continuously when cranking. Due to the other noises present it's best to ask an assistant to turn the key whilst you listen.

If that is all working correctly I would check that your filter clip is still ok.

Simon

Your account describes classic Fuel Filter Syndrome (FFS). The cause is slackening of the fuel filter case a pressure loss. Only the filter inself is pressurised by the fuel pump. The filter should be pressurised to around 50psi by fuel from the pump. If there's even the slightest leak from the body/cap seal, the engine won't receive fuel at the correct pressure and won't start. The only diagnostic test is to measure the fuel pressure at the injector rail on the engine. Itcan be done by attaching a dial gauge to the Schrader valve on the end of the rail. However, since the engine runs briefly on ether (Quickstart) you can be pretty sure of the diagnosis. So, you need the Fabled Orange Clip (FOC) at a minimum. This is the MGR solution and was a recommended add-on just before the company went down the tubes.

Here's the Bulletin about it: http://www.mediafire.com/file/dwu9ob...%2529.pdf/file

There are lots of threads (search term 'FFS') and a HowTo I believe. Ask here if you need more help.
If the FOC doesn't fix the issue, it's likely that the sealing o-ring has failed.


TC

Thanks for the responses. I fitted a clip a year ago.

Before I take the rear seat out and check filter, to measure the pressure on the rail, is it the connection that you can slide a tube on, blocked by a rubber sheath? I can't see a Schrader valve, assuming that's like a tyre valve.

I see you have the 1.8NA, which doesn't appear to have the valve that's present on the turbo version. Maybe try to connect a gauge where the fuel line joins the rail? The Rimmer drawing has a push-on connector by the look of it. https://rimmerbros.com/Item--i-GRID001924
Don't know what the 'rubber sheath' is. Is it the fuel feed pipe?

TC

It slides on the outlet to the very left of the Rimmer's pic you provided (the mushroomed pipe connector). A dust cover, I imagine, as it doesn't look like it would reliably hold back 50psi.

How does the fuel supply pipe connect to the rail? Is there a way to fit a gauge to the pipe?

Just remembered this same discussion earlier: http://www.the75andztclub.co.uk/foru...d.php?t=251267


Here's what you're trying to do (Turbo in this case): http://www.the75andztclub.co.uk/foru...l+gauge&page=2


TC

Solved - the car simply ran out of petrol. :duh:

The fuel gauge is telling porkies, indicating over 3/8 of a tank. I topped up with some cans and it started straight away. Trouble is with my kids living back at home the 25 and ZT are treated like pool cars and I have no idea of their mileage and re-fuels. I'll have to keep records until I free the floats. Not stopped raining all weekend though!

I took some IPK readings: (--6.1, as usual always indicates ______)

Non-start: assume empty tank (Gauge indicates just over 3/8)
__6.0 __0218
1_6.2 __0219

Adding about 8 litres from cans: (Gauge indicates 1/2)
__6.0 __0349
1_6.2 __0347

Adding another 18 litres at a fuel stn: (Gauge indicates just over 7/8)
__6.0 __0555
1_6.2 __0493

Conclusion - the computer thinks it has more fuel than it does. With and empty tank it thought it had ~21 litres. With 26 litres added it thinks it has ~52.

Has this fuel gauge error just become apparent or could it have started after you fitted the orange clip? This sort of error can be related to a mis-positioned float arm. However, your readings have a fixed offset equivalent to about 21-22 litres. That suggests to me a fixed resistance fault associated with the rheastats. Basically each float has a rheostat which are in series and their combined resistance is interpretted by the system to display the contents. So, the ECU seems to be seeing at least the 21 litre resistance value, plus any extra due to actual fuel.

https://www.mediafire.com/convkey/18...kyll44v76g.jpg

Maybe checking the individual resistance values using at tank connector plug is the first step.


https://www.mediafire.com/convkey/20...727zkia36g.jpg

Note that both should read about 5 ohms when the two sides are 'empty'.
With a reasonable amount of fuel in the tank, both readings should be similar.
Assuming linearity in the rheeostats and float heights, you can calculate what 21 litres equates to
So, if one reading is that much different from the other, you might have something to go on.

TC

I had a fuel gauge problem over a year ago, and fitted the foc whilst sorting that. The car is needed for the working week and it’s been raining constantly here, so I’ll have a look at the floats next weekend. I reckon the side with the highest resistance is the stuck up one...