91 3.9 losing losing power momentarily

Hi,

My 91 V8 has had a very intermittent fault since buying it in May. Every so often it would, for a split second lose power. The rev counter would drop but almost immediately it would be fine again.

As it was only a handful of times on 6 months i ignored it, however today it has done it several times in a variety of situations. I was towing a loaded horsebox amd although it didn't stop or even slow down it was/is a worry. It also did it without the trailer.

Any ideas what it could be?

It may be unrelated but it runs rough from cold and i have bought a replacement coolant temperature sensor in case it is over fuelling (smells of petrol a lot and flooded the other day)

Thanks
Adam

It could anything from a weak battery to a clogging fuel filter, including a fuel pump on the way out or funky old wires somewhere important.

Tough to say. Start checking the easy stuff first.

My RRC had a few issues like that when I first got it. It was fixed when I went through the battery connections and earths and cleaned them up because my battery wasn't charging up well enough.

I had something similar to this, as already said, look at battery and alternator.

If you get a misfire under load with say heated rear screen, heater and main beam on then I would say alternator. What voltage are you seeing at the battery at idle? What voltage do you get from the main terminal on the alternator and ground?

I think the battery is good, judging from how well it turned over repeatedly when it was flooding the other day! The alternator looks new-ish but will give it and the earth connections a good check over tomorrow (hangover willing of course!). I don't have a meter so can't check the voltage.

Interesting regarding it being under load, i did have heater on (full speed as resistor pack gone!) htd screen, wipers and lights so will check the alternator.

Fuel filter changed at service 2 months ago and intermittent issues started before this.

Whne the ignition is on and for a while after starting there is a noisy pump, which i had thought was the ABS pump. Could this be the fuel pump? The noise is coming from the drivers sider inner wing.

The fuel pump is in the fuel tank.

Cheers, you may have guessed my skills and knowledge is basic!

I do recall now its in the middle on the top as i had a problem with a fuel tank vacuum on a previous RR - i got half way through removing the tank and a friend suggested releasing the fuel cap....a little embarrassing when it fixed it!

I guess i have noisy/leaking ABS pump then?

They just make noise, even when they are working properly.