Won't start - has spark... Running out of things to try..

[Rob_Melb]

I've had my 1997 MGF 1.8VVC (Mk1) for around 15 years now, but over the last 7 years, it has not gotten the love it deserves. It sits outside under a heavy-duty car cover and gets driven rarely (i.e. kids have taken precedent for now) - so it is paying me back by refusing to start... It is well overdue a service and hasn't been started for over 6 mths.

I've reached a dead-end and I'm looking for help... I've read a bunch of historical posts and learnt heeps, but not enough it seems!

In attempting to get it started I have:
- ensured that I have adequate power to turn over the starter fast - didn't start and no fuel pump sound
- confirmed the fuel pump was dead and replaced it
- add in new fuel and tried to start it (connected to another car for power) - no luck
- checked all the fuses with the multimeter - all were good
- took out a spark plug and confirmed a spark - yet no fuel smell
- checked the fuel filter - fuel is clear and flows through - pumped out some fuel before and after the filter - all looked good
- got some aero-start and got it to turn over - but only on the aero-start - no fuel it seems (only the smell of burned aero-start)
- pressed the inertia switch - then aero start - fired but no fuel smell
- by-passed inertia switch (i.e. joined the pins) then aero start again - fired but no fuel smell
- reset the stepper motor and tried unplugging it - then aero start again - fired but no fuel smell
- checked all of the cable connections I could find - all seem ok - and yes tried to aero-start it again - no luck

I'm now stumped - it ran fine last time I had it running and it has a history of starting the first time every time... Anyone got any ideas...?

I'm thinking I need to check the ECU next - but I can't imagine why this would fail - they seem reliable - and I don't have a MK1 reader... If anyone has one in Australia/Vic and is willing to help - please reach out...

[Charless]

I had a similar story on an F unused in 7 years. It turned out to be the fuel pump. You should be able to hear it for 3 seconds when first switching on the ignition. Generic replacement fuel pump motors will only work if the ageing plastic pipes can hold their pressure which is about 3 bar.
I got rather over involved with fuel pumps a couple of years back. Some of this may help viewtopic.php?f=8&t=25603&p=195536&hili ... mp#p195536

With a couple of my 'repairs for interest' the pumps would run fine unloaded, but when trying to pressure up the rail had insufficient pressure to allow enough fuel into the cylinders while the injectors were open. So there would be a slight smell of fuel but insufficient to run well. I too found the engines would run quite well on accelerant alone - in my case brake and clutch cleaning fluid!
A couple of spare fuel pumps that had been taken out of working cars never worked again once they had dried out - there isn't a drop of lubricant in their working parts after a lifetime of petrol washing and they quickly corrode solid.
Good luck with it and do let us know how it goes.

[Rob_Melb]

Thanks Charless!!! Is there an easy way to determine if the fuel pressure is adequate? Or to test that the injectors are firing?

The pump doesn't seem to run for a full three seconds - and it doesn't run each time I turn on the ignition - if I try and then try again immediately after, the pump won't run - I assume this is normal practise to avoid over priming. Right?

Could there be an airlock and if so how would I clear this?

Since the last post, I've done the following:
Took out the fuel pump again, checked the tubes were properly connected and tested the pump - the pump worked well.
Check the voltage at the pump on ignition - it is good - yet I think it stays high for less than 3 seconds.
Looking at the tubes from the tank to the pump to the fuel rail - they all look good too.

Also, I replaced the spark plugs - just in case the spark was weak - no change in behaviour - still not starting... I'm still pretty confident it is a fuels system problem - as the CRC Aero Start fires...

[Charless]

It won't be an airlock - which would purge either through the injectors or the rail pressure relief back into the tank if the pump is pressuring up the rail correctly.
If you measured the pump voltage with a digital multimeter it probably uses an algorithm to calculate voltage before displaying it, so the 'less than full three seconds' may simply be this delay.
It is not so likely but if the pump isn't priming for 3 seconds with the initial ignition switch-on, then there might be a problem with the fuel pump relay or the wiring between them. This is located on the rear bulkhead with the ECU; there are several multi connectors on these units and all of them won't be hurt by a spray of contact cleaner and careful remaking. But access isn't so easy and I don't like disturbing 'old wires with memory set' - steady as she goes!
Injector operation is controlled by the ECU and I don't know of an easy way to check it, even with an oscilloscope, access to T4 or pscan 'readers' may be the only way.
When you say you replaced the fuel pump was that a generic pump or a complete MGF pump assembly? I did find the pipe clips need to be special high pressure fuel ones as normal jubilee clips can't contain the high pressure on small pipes.
My suspicion remains with the pump output being inadequate under load which is what held me up in similar circumstances. Good luck!

[Rob Bell]

Hi Rob

Sounds like you've done all the sensible stuff already. You are clearly not getting fuel delivery. If you are satisfied that you have a working fuel pump and the fuel line pressure is up to 3bar, then the problem may be with the injectors. They are either not getting the electrical signal to open from the ECU, or old fuel has congealed and the injectors are blocked (lots of way to test this, but injectors should make a ticking noise).

Fuel line pressure can be checked with a fuel line gauge, but assuming that the fuel pressure regulator is working, then when the injector rail is up to pressure, fuel will then be returned to the fuel tank - so this will start flowing. If dry, the fuel rail is likely not getting up to 3bar pressure.

[Rob_Melb]

Thanks for the help gents - much appreciated.

Given your sound advice - I’ll check that
1 fuel is flowing via the return line
2 the injectors are ticking
3 accurately time how long the pump runs for
4 connectors on the relay

Anything else - let me know..

And try to find someone that can read the ecu in Melbourne Aust… game on…

[Rob Bell]

Good luck Rob - and let us know how you get on!

[RobboMC]

On the weekend I managed to 'trigger' the inertia switch in my Mk1 F while driving.

I was driving in an area that has recently been affected by heavy rains and flooding and I hit a big pothole with the left rear
with enough jarring that the switch turned off the fuel pump.

Fortunately I was able to realise what happened and hit the reset button and drove onwards.

The symptoms appear similar to yours, have you pressed the reset button on the inertia switch yet?

On my case, I'm happy to have 'tested' the switch as now I know it will work if the worst happens.

[Rob_Melb]

Re: inertia switch - I have reset it and bypassed it - no luck...

I think all is pointing to either a faulty replacement pump (i.e. not enough fuel pressure) or blocked injectors (i.e. fuel gunk) or ECU...

Yet to complete the tests above - work has got the better of me - so will not complete them until the weekend. Thanks all.

[Rob_Melb]

Hi gents, I have run into some challenges - long covid and a very sick daughter (plus house renovations) - so all testing on the MGF has been sidelined... Thanks so much for your help - I'll get back to you as soon as I have the time/energy to get some work done on the car.

[nigelandjo]

Hope you're soon feeling fit and able to resume work on your car.

[Rob Bell]

Hope your daughter and loved ones are on the road to recovery Rob - and good luck with the house renovations!

[Rob_Melb]

Thanks Rob and Nigel!!! I can see the light at the end of the tunnel - and at the end of that tunnel is my broken MGF awaiting some love and attention...

The good news is - my daughter is recovering nicely, and the reno has left me with a new garage and workshop! I just now need to get the builder to clear out his stuff and then get some mates over to help roll the MGF into the garage so that I can get to work on it... I reckon I'll be back on it by the end of Oct...

My first stop is to check out the fuel pressure and injectors - to work out why I'm not getting fuel to the cylinders... Hopefully, this will uncover the issue... Time will tell.

[Reckless Rat]

I had a similar problem a few years ago, which was caused by a break in the boot loom wiring ( a well known MGF problem). What had happened was that the earth feed to the fuel pump had failed. I rigged another connection to earth from the top of the fuel pump and all has been well since.

[paul_mgb]

I had a similar problem - broken wire by the hinge of the boot. I'm not sure what it did suspect it was the ECU earth, it was black with a white stripe. My mate Bob found it after I spent hours fiddling with fuses and relays. The nut for the hinge had caught the wire and snapped it.

[talkingcars]

........ The nut for the hinge had caught the wire and snapped it.

Usually the wires fail as the plastic outer goes brittle so doesn't flex when the boot is opened.