Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing 3.9 v8 cuts out at bottom of a hill

Above the wiper motor on the bulkhead. In this photo it is the black thing behind the siphon tube as it leaves the expansion tank. Push it in hard from the top.

On my 94 +8 it is located on the lower side of the bulkhead to the right of the charcoal canister.

Hardly likely to be inertia switch as that would need re-setting at the bottom of the hill before starting again surely. Try blocked filler cap vent.

I had a look at the cap but I couldn’t see a vent, where should I be looking to check?

Probably vents through an EVAP system on that age of car via a charcoal canister. I.e. no vent in the cap.

Don't know how that works on the Plus 8 though.

When take the fuel cap off is there a whooshing sound, if not it's not a blocked vent. Low pressure fuel pump in tank (if it has one)

I have always had a wooshing sound on my 94 +8 when removing the fuel cap, I thought they all did that?

No fuel tank vacuum issues after checking yesterday and so I’ve still not found the solution, and to give it a go I fitted a new Lucas idle control valve which has made it worse.

On a test run yesterday the car now stops on the flat too, but what I found, which would possibly explain why I thought it was just hill related, is that it stops after being on over run for a while such as purely engine brake slowing for a roundabout on a faster road. If I stop quickly with little to no over run it’s fine.

The actual moment it dies is just as I’m coming to a halt and depress the clutch at which moment the revs drop and do not come up again.

The car starts immediately after stopping, it idles at 800 and if I blip the throttle the revs dip to just below then come back up to 800.

Anyone got any thoughts what to look at next?

Does it misfire at all? Just thinking out loud, my iacv (stepper motor) has stuck open on occassion, causing misfire and sudden drop in revs/loss of power when coming off the throttle. I managed to give mine a good soak overnight and refit successfully restoring it to normal operation. Appreciate you've fitted a new one, but could be gunk in the iacv idle adjust port interfering with flow. Have you tried any maf/carb/egr cleaner in there, and the maf etc? The other thing to check might be the vacuum hose on the fuel pressure regulator, although a leak here would presumably cause more constant issues.

Question: Does it start doing this from the get go i.e. when the engine is not yet warmed up does it show hesitancy or only once the engine is warmed up?