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krytensmeghead

S3 Turbo Engine stops

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I have a similar issue with my s3 Turbo.

Sometimes after about 20 minutes of driving it SEEMS to be starving of fuel and I have to give it huge throttle to keep the engine running till I can pull over somewhere. This results in high boost pressure but no torque.

As soon as I turn off the engine, leave it for a minute or so, then start it again it's back to normal. Sometimes I can drive it for an hour and this doesn't occur.

The Dellortos have been rebuilt with the proper turbo kit. Fuel pump and filter is relatively new given it only gets driven for a couple of hours every 2 months on average ( using fuel stabiliser ).

Tanks were flushed a couple of years ago after being in storage since 2002. New fuel pressure regulator set to 4 psi.

New ignition coil and points about 1 year ago.

New fuel vent tubes.

This model doesn't have a charcoal canister.

I have replaced all the relays.

The problem doesn't seem to be effected by temperature - happens day or night, no extreme temperatures.

I'm thinking it's something to do with the fuel as I can't imagine an electrical problem fixing itself every time I stop the engine and restart.

There are no electronics involved with this engine but it has the constant energy ignition ( CDI ? )

I've just drained the fuel by disconnecting the hose to the fuel pump and there was no interruptions in the flow - coming out very fast with no visible debris.

Not sure where to go from here.

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Assuming the carbs are ok and with correct float levels I would still look at the fuel supply before the pump. Original tanks? I had a similar intermittence issue on mine and it improved after changing plug leads and distributor rotor arm. I still had to change the tanks as they were rusty on the inside. That resolved it completely. There was debris. All it takes is a larger piece of rust floating around before the pump. That might not manifest when you run the pump consistently to empty the fuel tanks (it did not on mine yet the rust was there). I would want to know how the tanks look in the inside and verify it if I were you and before changing more parts. Besides that, make sure the ignition amplifier has a good solid ground. 

 

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I inspected the tanks using an endoscopic camera and there is some surface rust inside.

Before changing fuel tanks I installed a new aluminium tank in the boot area to see if it fixed the problem.

It's worse than before. I replaced the fuel filter at the same time as the tank but not the pump.

It is now very reliable, as it reliably dies after driving for about 10 - 15 minutes.

It was running really well then started to run a bit rough and was loosing power.

Then it just stalled.

Last time it did this I couldn't start it for about an hour ( tried starting it after about 20 minutes but it wasn't even trying to fire )

It started immediately as soon as the road service guy turned up about an hour later without doing anything.

I thought it might be pulling a vacuum in the tank due to a filter restriction I used  on the tank vent line . This was there to make sure only air went through the vent line.

Today I removed the vent filter but made no difference. It was running well for about 5 - 10 minutes but started to stutter again.

This time I made it home but don't know what to do next.

Is there some sort of filter inside the fuel pump that could still have some crap from the old fuel tanks ?

The car's done about 200 Kms with the current fuel pump.

The pump was still running and changes tone when I squash the hose.

It seems that it's using up what's in the carbies then dying.

To check the fuel pressure do I need to have a gauge before or after the fuel pressure regulator ?

The pictures I've seen show a gauge before the regulator only but that seems counter-intuitive.

However I don't know if the dual output of the regulator is just a tee inside or 2 independent pressure controlled outputs.

I could buy another pump and fuel pressure regulator but need to stop throwing money at it with all the associated lead times replacing parts and not fixing the problem.

I've already spent about a month on a wild goose chase replacing and cleaning all the ignition components.

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If its the original mechanical fuel pump ( and the same as my NAa?) then yes, there is a filter in it.

i got crud that covered an (old) 50p piece out of mine. Worth a strip and clean, I suggest

 

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It would be unusual for two problems concurrent, and the earlier situation of s short re-start isn't in line with what I'll suggest checking for, but the new state is in line.

Check that you have a decent spark when you have a failure, as there are failures (such as rotor arm with rivet, but not only that) which could lead to a 15-45 mins cool down being required. If checking the spark strength isn't an option, then simply pulling the plugs should give an idea as a dry plug would indicate fuel and a wet plug ignition. I'm just thinking that  testing and diagnosis is better than a seemingly endless parts-replacement programme.

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No it's electric.

I think it was this one :

https://www.sjsportscars.com/parts-and-accessories/SJ082L0002.htm

Crimped together so probably not serviceable.

I might try reverse flushing it but going on the law of averages another akward messy job that won't fix the problem.

I think the high pressure ones are positive displacement roller type that may not allow flushing without the motor turning.

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Thanks Andy,

I'll check the spark next time it happens. It has a new Distributor cap and rotor button.

This is what I've been through so far :

 

 

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The AB14 amps have a nasty habit of failing but being difficult to diagnose, as do the engine speed limiters.

 

 

For anybody reading later on, SJ do the plug leads but seem to have not listed them in the <88 TE section, so it;s these ones (same as NA etc) .

https://www.sjsportscars.com/parts-and-accessories/SJ634.htm

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Thanks, I couldn't find them searching in the turbo section.

I just got some off the shelf individual leads, also ran them away from the engine instead of being jammed between the head and heat shield in case there was any arcing to the engine occurring.

If i change them again i'll probably get these because I hate trying to fit a highly flexible lead boot to a spark plug when I cant get mt hand anywhere near the plugs because of where they've buried them.

Too much chance of kinking the new leads.

image.jpeg.f6b8ad55ac7a8936028caf92fd20f154.jpeg

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Would the Lumenition  module die then come good again ? Is this a normal problem with these ?

I have a hall effect conversion for this distributor but didn't end up using it because of where the distributor is and didn't want to replace the Lotus designed system with a poorer one.

It goes from the pick up straight to the coil with no other amplifier.

I think it might be this one but can't be 100% sure. It's been sitting in a box for ages. I just used the coil out of it.

https://www.sjsportscars.com/parts-and-accessories/SJ083M0005.htm

I just took this photo of it.

Hall Ignition.jpg

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Ah, well if yours is the Lumenition system, then that rules out the AB14 as that's art of the later system, but yes they do start with intermittent failures. The speed limiter can probably be found by tracing the spare set of wires from the coil, and again, these can fail intermittently. The problem with the failure on these is that it's often a case of them heating up (over-heating as they fail), then they cool and things work again.

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I've had the cover above the RH fuel tank off several times and haven't noticed anything like a  speed limiter module but maybe there is one there.

From the generic circuit in the manual I would presume it shorts the negative signal from the distributor to ground so simply unplugging it should stop it effecting the ignition.

Is that correct ?

1192220035_SpeedLimiter.jpg.329f0521dbc3879b9a0bd41a8249283c.jpg

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That's right,  it's absence will allow the engine to run (unlimited), plugged-in it will stop the difference in voltage across the coil (above the set frequency).

Edited by andydclements

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The speed limiter usually sits atop the RH rear wheel arch. It’s connected to the same cable string that runs from the ignition box through a grommet and up into the right hand ‘cable channel’. The 3 pin connector is flat and wide, black in color. Mine doesn’t have a limiter. So if yours has a limiter just disconnect it and see if that makes a difference. Good luck with the troubleshooting glen. It sounds a bit like a wild goose chase. Did you actually change the tanks or still operate with the extra tank in the back? I still think it’s a fuel starvation issue by the sound of it, but that’s just guessing. 

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Thanks Gis,

Today I took the inlet hose off the fuel pump to see it any debris came out but as I suspected the fuel can't drain backwards through the pump.

I haven't done the bucket test for the flow rate yet but I installed a fuel pressure gauge just before the fuel regulator valve and the pressure was down a bit.

Unfortunately I gave it about half a turn before I found the gauge so I don't know what it was originally but it was just under 4 lbs when I put the gauge on.

I adjusted it up to 4.5 lbs and drove it for about 10 minutes. It did seem better but started to stutter under load ( boost ) so I got it back home before I got stranded again, so I don't know if it would have stalled.

I'll probably have a look for the rev limiter tomorrow but i think it's fuel.

I did see some discoloration in the inlet of the pump so there could be something in there.

I would have thought the rev limiter would suddenly shut off the ignition, not run rough under load.

I'm still using the after market tank in the boot.

I won't be changing the tanks. That would turn into a $5000 exercise with shipping and exchange rates. Then try to actually fit them.

If I have to do any more major surgery on this thing I'll probably remove the motor bike engine they put in there and use a 3.8 litre V6 that has natural torque, no cam belt and only 2 hoses for the cooling system ( + 2 for the heater ), probably mated to a subaru auto.

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I think 5k for tanks is excessive. A set of alu tanks will cost you 500 pounds plus shipping. That’ll be like 1-1.5k aud approx. It’s a doable job. With all the work you’ve done already it’s worth sorting it. Also, the pressure regulator spits all excess fuel back into the tank and the whole system is ventilated via a breather pipe. With a single closed tank in the back you might be sucking on a vacuum... hang in there mate and sort it. It’ll keep the value of the car and cost a lot less in the long run. I’d never consider swapping engines. Going electric in the future and dress up the old lump and put it in the living room perhaps some day yes 😉, but there’s very few G cars down under and yours looks really nice. 

The LTE and delorean combo is a killer by the way. Really nice 👍

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Pull the old tanks out and get them fabricated locally. For an experienced tank builder it’s a simple job. I had a set made out of food grade stainless for the v8 - £400 for a pair of tanks 

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I thought the tanks were about 500 pounds each - looks like 260 pounds each on SJ but can't really deal with doing the job at the moment.

I recently bought a body kit for the Merc for $1270 US. By the time the conversion rate, shipping, import duty, GST and Customs Broker fees were added it was over $4500 AU.

I could get some tanks made locally. I'll probably find out about the pin hole after they're installed.

Obviously there will be no leaks before they're installed - that would ruin the surprise.

( you might notice a touch of pessimism starting to creep in )

 

Regarding the engine it could still be the ignition breaking down when there's boost so still multiple things that could be causing the problem.

The engine's only done 47,000 miles so probably would be a waste swapping the engine but it's no where near as drivable as the $1200 Commodore I use as a daily driver.

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Wow 💷 them import duties whack it up.

get em made local chap - think of your fellow countrymen 

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Can you replace a fuel line with a clear section rather than black rubber to see if you are getting fuel through?

My immediate thought would be a vacuum is being created in the fuel system, or that a piece of waxed paper (wont dissolve in petrol) in the fuel tank is drifting on to the fuel pick up after a while causing fuel starvation, and then when the engine is off and the pump releases it it drifts back in to the tank again.

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Not sure if the system is Lumenition or Constant Energy as both seem to be mentioned on this thread.

But if Lumenition these require a ballast resistor. Is there any chance the ignition has been accidentally rewired such that this is bypassed? If there is no ballast resistor the coil will overheat and its internal cutout will activate. This resets itself after the engine is off for a few mins.

 

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Just a thought. Have you tried removing the spark plugs after it’s cut out, and turning the engine over to see if you have a spark at the plugs?

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I tried that but it doesn't take long for the spark to be there so not sure if that's what is failing.

I can test for spark but it still runs badly and keeps stalling.

I finally found some info about the Lumenition system regarding ballast and coil values. There was more than one variation of this and the later ones apparently use a different coil.

Turns out my coil is more than double the resistance it should be @ about 3.5 ohms.

Apparently I need the MS4 coil with about 1.5 ohms and ballast resistor at about 1.5 ohms

 

This probably should be archived somewhere so others can find it as it took many hours to find the info.

Lumenition_Optronic_Description.pdf

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