Engine issue

[911GP]

Hello,
First drive of the year for me today (in the rain).
It was a 140 mile round trip. Car started and drove well all the way out and 95% of the way back home. A couple of miles away from home the car felt like it was losing power and started to judder a bit. I pulled over and alternator light was on. I then started the car again and it fired up immediately. I pulled off again but had the same issue. This time i was in first and second gear and had the accelerator pedal down quite a bit but felt like I was losing power and engine revs were low. Again loss of power and engine cut out so I pulled over again. This time I waited about 5 mins and then started the car and managed to get home without further issues and the car felt fine. Do you clever folks have any ideas what could be the problem? Sorry but I have little knowledge on mechanical issues. I don’t think it is the alternator since the car started up again immediately. Maybe a fuel issue or an electrical issue? Coil?

This has happened once previously but not as bad as today.

Many thanks
Gitesh

[Nine One One]

Did you leave the old ethanol fuel in the tank, and its ‘gone off’ ??

[911GP]

Thanks for replying. I had filled the tank with Esso Super and added the Porsche Classic Fuel Additive last October. I know Esso were going to start adding Ethanol to their Super around year end 2023 but not sure if the tank I filled had any Ethanol in it. Also seems odd that I managed to drive 140 miles on the same fuel tank before the issue transpired. There is about half a tank remaining now according to the fuel gauge.

[neilbardsley]

Fuel pressure? Happen to me recently. Started well but struggled when pushed on. Perhaps replace all the fuel filters. Blow out pipes. If that doesn't help measure the pressure?

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[Gary71]

Collapsing fuel line maybe? Stopping just lets it recover long enough to get something through then goes again.

Is it misfiring or just losing power?

What engine/fuel/ignition system? Your MFI 2.7?

[911GP]

Thanks for replying.

It was not misfiring, just losing power. Accelerator pedal was down quite a way in second gear and I would have expected quite high revs (5k or so) but it just wouldn’t pick up and started jerking. It is a standard 2.4E engine with MFI and a Classic retrofit CDI+ and original black Bosch coil.

You two could well be right with a fuelling issue. Something to look into.

Thanks
Gitesh

[Gary71]

If not clearly misfiring then it still had at least some spark and some fuel.

Spark tends to be binary rather than partial failure, so a whole engine power reduction I’d definitely call fuel supply out first.

Unless of course your floor mat is under the throttle pedal or the linkage is about to drop off!

[hot66]

that almost sounds like its over fuelling as if the thermostat hose has come loose and its gone to full rich ... but if that was the case it wouldn't recover itself and then be ok . Did you notice whether it was puffing black smoke ?

In the unlikely event it is that, was there any different noises eg popping back up through the stacks or popping in the exhaust ? I assume you've had a look around the engine bay to make sure no electrically connectors have come off or are loose ?

Do you have a spare coil you could try ?

[911GP]

Hi James,
Thank you for replying. I'll take a look again tomorrow but I don't think any connectors have come loose. It was all put together well during the restoration.

I do occasionally get a popping sound from the exhaust once the car has warmed up. Giulio at Gary Cook's said this was the case when he had a look a while ago and I haven't got around to addressing this with the CDI+ box override. Pardon my ignorance, but why would running rich/over-fueling cause the issues I am having with the lack of power and engine cutting out?

Thanks
Gitesh

[hot66]

Hi James,
Thank you for replying. I'll take a look again tomorrow but I don't think any connectors have come loose. It was all put together well during the restoration.

I do occasionally get a popping sound from the exhaust once the car has warmed up. Giulio at Gary Cook's said this was the case when he had a look a while ago and I haven't got around to addressing this with the CDI+ box override. Pardon my ignorance, but why would running rich/over-fueling cause the issues I am having with the lack of power and engine cutting out?

Thanks
Gitesh

It won’t be this by the sounds of things….. but for interest if the thermostat hose comes loose so no hot air gets through ( or in my case the circlip popped off the thermostat rod ) the mfi goes to full cold start rich. When it’s this rich the engine won’t rev and feels like it’s choking

[RobFrost]

Hi James,
Thank you for replying. I'll take a look again tomorrow but I don't think any connectors have come loose. It was all put together well during the restoration.

I do occasionally get a popping sound from the exhaust once the car has warmed up. Giulio at Gary Cook's said this was the case when he had a look a while ago and I haven't got around to addressing this with the CDI+ box override. Pardon my ignorance, but why would running rich/over-fueling cause the issues I am having with the lack of power and engine cutting out?

Thanks
Gitesh

A hot engine won't run well with an overrich mixture. Additionally, the plugs may coke up, causing the problem to get worse during the course of a journey. The problem may be worse during acceleration because fuelling systems are designed to provide additional enrichment during climbing revs which exacerbates the problem.

You can add strength to this hypothesis by confirming the plugs are sooty (black).

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[911GP]

Thanks, gents. Seems like there are a few things to check. I will reply back if I find anything or can replicate the issue with more details.

Thank you