Weird non starting problem GT6

[rulloyd]

Hi all

Since restoring my GT6 (completed this year) my car has been as good as gold starting.  But today I had a problem which I can’t see any obvious explanation for.

As I haven’t driven the car for about 2 weeks, turned over quite a few times before the fuel got through the system.  The battery did suffer a bit as a result but all was running fine so off I went (note to self always prime the pump after a period of non use).

First stop petrol station where unusually I filled it to 3/4 full (1st time since rebuild).  Started fine.  Next stop Sainsbury’s, 5 mins turned off, turned over fine but would not start or even bite.  In the end battery started struggling. Baffled.

Left it for 20 mins whilst I nipped home (courtesy of a very kind fellow shopper) to get some tools.  Tried again without doing anything, started on the key.😮

- Electronic ignition

- Low mileage inline fuel filter (ahead of pump)

Any ideas?  Thanks all.  TSSC advice always the best.  
 

Can’t be looking like a classic car loser at Sainsbury’s!!

On the positive side had some lovely comments at the petrol station.  Some very nice people out there 😏

Rich

[KevinR]

Choke stuck on ?

[DanMi]

depending on how long it stood before restoration, could be rust/varnish come off the inside of the tank blocking the fuel line.

[NonMember]

Kevin may have a point - my GT6 has been known to behave as if nothing's happening at all when the choke's on and shouldn't be. However, after a five minute stop you presumably didn't pull the choke out. Given the description of the day's trips, it sounds like a heat soak problem. If it keeps happening then I'd be suspicious of the electronic ignition. What type is it?

[rulloyd]

41 minutes ago, KevinR said:

Choke stuck on ?

Thanks Kevin but definitely off (I’d know as it idles like a train pending adjustment!)

[rulloyd]

16 minutes ago, DanMi said:

depending on how long it stood before restoration, could be rust/varnish come off the inside of the tank blocking the fuel line.

Possible.  I cleaned out the tank best I could* but the tank did have some rust in and this is the first time with a near full tank.  But why would it solve itself after 20 mins?

* Originally I used a rust converter but had to replace that tank in a hurry after it developed a rust hole (!) so all I managed was a swish out with Petrol of the replacement.

[rulloyd]

30 minutes ago, NonMember said:

Given the description of the day's trips, it sounds like a heat soak problem. If it keeps happening then I'd be suspicious of the electronic ignition. What type is it?

Electronic ignition is newtronic.  I bought it about 25 years ago but has had little use (although I did have to put a join in the optic cable after it was cut).  I’m pretty sure the join (soldered joints) is fine.  
 

What would you expect could be affected by heat soak that would cause the problem?  I have frequently encountered the starter motor struggling after a short stop before but only for 1 or 2 turns then it spins normally.  Always a concern that one, but the engine is still running in (300 miles only) so I’m assuming the engine will loosen up?

cheers

Rich

[chrishawley]

I'm supposing there will be a wealth of experience to advise you on this so I'll just stick to factors which I've experienced first hand: For 'die then recover' I've had:

* Fuel tank shedding detritus enough to partially obstruct the forward fuel line. The tank had been refurbed but shed an atrocious amount of crud after it's first fill.

• Obstructed needle valves in one or both carbs - general filth +/- flakes of rubber from fuel lines

• Obstruction of the interconnecting pipe between the carbs

• Carb flooding due worn needle valves (not returning) or poorly fitted sealing washer between NV and carb body (leaking)

• Intermittent loose/poor electrical connections almost anywhere from battery through to distributor.

• Impending failure of electronic ignition unit (Accuspark) - intermittent problems first, follwed by complete failure.

I guess there are many other possibilities beyond my knowledge but those are ones I've dealt with first hand. Hope that helps with thinking about the problem.

[rulloyd]

14 minutes ago, chrishawley said:

I'm supposing there will be a wealth of experience to advise you on this so I'll just stick to factors which I've experienced first hand: For 'die then recover' I've had:

* Fuel tank shedding detritus enough to partially obstruct the forward fuel line. The tank had been refurbed but shed an atrocious amount of crud after it's first fill.

• Obstructed needle valves in one or both carbs - general filth +/- flakes of rubber from fuel lines

• Obstruction of the interconnecting pipe between the carbs

• Carb flooding due worn needle valves (not returning) or poorly fitted sealing washer between NV and carb body (leaking)

• Intermittent loose/poor electrical connections almost anywhere from battery through to distributor.

• Impending failure of electronic ignition unit (Accuspark) - intermittent problems first, follwed by complete failure.

I guess there are many other possibilities beyond my knowledge but those are ones I've dealt with first hand. Hope that helps with thinking about 

[rulloyd]

Thanks for all the good suggestions Chris.  Seems like the most likely reason is crud from the fill up otherwise a little too coincidental.  

Funny that it happened after I stopped though (no misfiring) And was fine after it later started.  

All my lines are new and use ethanol resistant rubber pipes where appropriate.  My filter in in the line just ahead of the pump.   

I expect the carbs are ok as I just rebuilt them.

First thing I looked at was for loose wires.  Looked fine but will check again.

Running as sweet as a nut right now!

 

[dougbgt6]

Rich,

I've had sludge in the fuel line, rubber slivers and a rogue fibre washer floating about and occasionally blocking the tank outlet. However all these caused rough running before engine death. In this case I would suspect something electrical, loose wire, dodgy connector or electronic ignition. Do you have a biased ignition system? Last year I had to replace my ignition switch because it wouldn't connect the 6v on start up. 

Doug

[NonMember]

10 hours ago, rulloyd said:

What would you expect could be affected by heat soak that would cause the problem?

I'd say the most likely candidate is the electronic ignition pickup - sensitive electronics that might well have been hotter just at that moment than normal. Next candidate would be the coil. If you had waxstat carbs, as Mathew said, they would also be a suspect. Or possibly a weak fuel pump, which might have vapour-locked then drawn liquid fuel back in as it cooled.

[Stratton Jimmer]

It's worth mentioning that if your battery is struggling, any attempt to use the starter motor will sap its charge very quickly. Electricity likes to use the path of least resistance and hence you may not get the necesssary 12 volts at the ignition system. This is a common fault with Japanese motorcycles - starter motor runs well enough but no ignition.

[thescrapman]

11 hours ago, rulloyd said:

Electronic ignition is newtronic.  I bought it about 25 years ago but has had little use (although I did have to put a join in the optic cable after it was cut).  I’m pretty sure the join (soldered joints) is fine.  
 

What would you expect could be affected by heat soak that would cause the problem?  I have frequently encountered the starter motor struggling after a short stop before but only for 1 or 2 turns then it spins normally.  Always a concern that one, but the engine is still running in (300 miles only) so I’m assuming the engine will loosen up?

cheers

Rich

The Piranhas / Newtronics seem to get dry joints on the pcb, also the big transistor plays up.

I run 4 of them, 2 I purchased as "fully working" from Ebay and were nothing of the sort.

The investigation revealed the dry joints, and swapping bits from a good one proved the transistor.

All have been running 20+ years now without any further issue. 

[Pete Lewis]

it   runs and then  stops .........wait a while kick the tyres have a  snooze and it starts

has all the hallmarks of the coil having reversed polarity 12v

make sure the dizzy trigger is on the neg   - and the ballast /ign feed is on the Pos + ( on neg earth cars)  opposite on pos earth cars)

this has caused many a involuntary  stop  over the years its often the case 

Pete

 

[Mark B]

Don't know if you a are using an original live lead from the battery to the solinoid, seen two types one clearly a larger diameter than the other. Only after occassional problems spinning over, I paired back the insulation on four original leads, and found they all had badly corroded along the length, covered in green corrosion. Replacd with new cable, problem solved.

I have problems starting my Gt6 from cold, if unused for a couple of weeks, everything replaced and adjusted I've put it down to a tired worn engine. A little squirt of easy start always works, and saves caning the battery. Maybe worth carrying a can for emergencies.

 

[PeteH]

Ford, ran a start system, which basically used a 6volt coil on 12volt systems, protection for the coil during running was by a Ballast resister, by passed by feeding the coil 12v via the starter during cranking. This meant at the point of lowest voltage during starting the spark was not deteriorated. Later they changed the resister for a resistive wire, which was often incorporated in the loom. (and which led some to assume it was a 12v Coil) The wire from the start solenoid was not separately switched, as normally only live when cranking. If said, solenoid, wire failed as little as 4volts could be getting to the coil which would result in a massively degraded spark and difficult (to say the least) ability to start!. A battery which was already low would exacerbate this phenomenon. Food for thought?.

Pete

[PeteH]

5 hours ago, Mark B said:

A little squirt of easy start always works,

One of the "Complaints" leveled at "easy start`s" is that they tend to wash the oils off the cylinder walls?.

I know back in the day we always had it for the (extremely) reluctant to start Ship Lifeboat Engines!!. But then we where more concerned to be able to get the boat away from a sinking ship`s potential to take us down with it!. Used it for years on old Fords and Fordson diesels as well. Saw it used by the wharfies to start brand new SAAB`s too in Sweden in Winter!.

[NonMember]

2 hours ago, PeteH said:

Ford, ran a start system

Same system on nearly all 1970s BL and probably others. It lasted until electronic (variable dwell) ignition systems became the norm. However...

2 hours ago, PeteH said:

If said, solenoid, wire failed as little as 4volts could be getting to the coil which would result in a massively degraded spark

Only if you have the wrong coil. If the solenoid wire fails, your 8V battery is providing 4V at the coil, which is 2/3 of normal operating voltage. That's exactly the same as if you have an 8V battery voltage on a non-ballast 12V coil. Failure of that wire (or, more likely, the extra contact in the solenoid) renders the ballast system no different to the earlier in terms of operation.

[rulloyd]

17 hours ago, Mathew said:

Are you running slightly lean? When you stopped the heat warmed the carbs and leaned it a bit more, after a rest it cooled a bit and allowed to start? Only mention it as it happened to my spitfire many years ago when we switched from leaded to unleaded, although it was due to the waxstats on the su's which would not affect you. Can we blame e10? I know last fill up my pumaspit had difficulty starting when i switched from standard to super unleaded, but with the same fuel is ok now,, probably adjusted itself!

Hi Mathew.  Possibly but I don’t think it’s the likely cause as I have been driving no problem up to this incident.

No e10, I am using premium only.  My car always starts easily (except this once)

[rulloyd]

13 hours ago, dougbgt6 said:

Rich,

I've had sludge in the fuel line, rubber slivers and a rogue fibre washer floating about and occasionally blocking the tank outlet. However all these caused rough running before engine death. In this case I would suspect something electrical, loose wire, dodgy connector or electronic ignition. Do you have a biased ignition system? Last year I had to replace my ignition switch because it wouldn't connect the 6v on start up. 

Doug

Hi Doug.  No rough running.  When I turned it off all was good. 
 

Could be ignition but I come back to the fact that the problem only just occurred this once, but the engine runs well.

I think it’s very likely linked to one the 2 unusual events.  1  that I almost flattened the engine starting it that day after a few week gap, when all I needed to do was prime the pump first.   And 2. I filled up to 3/4 of the tank, 1st time with this replacement tank, not pre treated.  But same fuel.

I have no idea what a biased ignition system is!!  It’s ‘normal’!

Rich

 

[rulloyd]

13 hours ago, NonMember said:

I'd say the most likely candidate is the electronic ignition pickup - sensitive electronics that might well have been hotter just at that moment than normal. Next candidate would be the coil. If you had waxstat carbs, as Mathew said, they would also be a suspect. Or possibly a weak fuel pump, which might have vapour-locked then drawn liquid fuel back in as it cooled.

Ok but it’s not happened before? (Where’ve I heard that…)

[rulloyd]

13 hours ago, Stratton Jimmer said:

It's worth mentioning that if your battery is struggling, any attempt to use the starter motor will sap its charge very quickly. Electricity likes to use the path of least resistance and hence you may not get the necesssary 12 volts at the ignition system. This is a common fault with Japanese motorcycles - starter motor runs well enough but no ignition.

Hi Jimmer.  That’s an interesting one and I’ve not heard of that. That’s a possibility but how comes cars Do start on low power occasionally if they turn over and over before firing?

[rulloyd]

13 hours ago, thescrapman said:

The Piranhas / Newtronics seem to get dry joints on the pcb, also the big transistor plays up.

I run 4 of them, 2 I purchased as "fully working" from Ebay and were nothing of the sort.

The investigation revealed the dry joints, and swapping bits from a good one proved the transistor.

All have been running 20+ years now without any further issue. 

Thanks Scrapman.  But other than this one non start it’s running fine?

[rulloyd]

12 hours ago, Pete Lewis said:

it   runs and then  stops .........wait a while kick the tyres have a  snooze and it starts

has all the hallmarks of the coil having reversed polarity 12v

make sure the dizzy trigger is on the neg   - and the ballast /ign feed is on the Pos + ( on neg earth cars)  opposite on pos earth cars)

this has caused many a involuntary  stop  over the years its often the case 

Pete

 

Hi Pete.  It runs fine and doesn’t stop till I turn it off!  This is a one off instant after I parked up.  Is this then likely?

Rich