My 3.5 v8 runs for about 2-3 miles Then the power drops off, if you switch off and leave it for 5 minutes it will run fine then the same thing after a few miles, there’s no response on the throttle once you go past half way.
Thanks
Chris

I have had something like that on a different vehicle, it was a blocked fuel tank breather causing a partial vacuum in the tank.

Funny you should say that I have just picked it up from the garage and that was one of the things they have changed on it.

CRS said:

Funny you should say that I have just picked it up from the garage and that was one of the things they have changed on it.

Click to expand...

Try it with the filler cap off.

Blocked fuel filter or worn fuel pump?
Any damaged fuel lines underneath?

I think it’s definitely a fuel problem, I have noticed that the fuel pump is very loud, not sure if that’s normal or not, I think it’s under the rear seat, this is a 79 two door Range Rover.

The fuel pump is under the vehicle, RHS close to the rear seat.

It could be tank vacuum, it could be a clogged fuel filter (there is one in the pump as well as the one in the engine bay, you can twist the bottom off the pump the get at it), it could be a tiny bit of rubbish sitting against the fuel inlet needle valve on one carbie (had all happen to me, and the last one takes some working out ). Another issue I had was rubbish in the fuel tank which would clog the inlet after a few minutes and the vehicle would lose power. Once you stopped for a few minutes it was fine again as the rubbish fell away from the inlet. That was tank out to clean about 3 times to finally get it all. (And it was a 150l long range steel tank too ......).

Other thoughts, it could be a coil dying as it gets hot, although that is usually accompanied by the engine missing. Also has someone fitted an external resistor to the coil? They run a 7V coil but the resistance is internal to the vehicle wiring. Some people don’t realise this and fit an external resister and suddenly you have a 7V coil trying to run on 4V.

Get the engine hot and when it cuts out, check you have sparking on all the plug leads, are they individual coils or packs?

Ok thanks everyone, lots of things to look at.