Revving problem ?

[MCGRAW80]

Hello! New to the forum. Have a problem with the high idle. . Revving at 1100 at idle all the time even when warmed up. I've read that this could be the cold start mechanism. . Anyway the problem that is maybe the most concerning is I can be travelling along motorway at 70mph and I'll feel the van lurch forward like I'm putting the foot down and the revs shoot up. This tends to happen if I've a quarter tank of fuel. ( doesn't do it if the tanks fuller). Also sometimes if I've been driving a couple hours I'll pull over for a break, stop the van and the revs shoot up to 2500. Turn engine off and on it'll do it again, shoot up to 2500. Then I'll turn it off and on again and it'll settle back down to 1100. Just wondering if any of you knowledgeable guys could point me in the right direction as to what it can be?  It's a 54 plate 1.9 diesel van. 150000 on the clock. . Thanks?

[brodfather11]

Welcome to the forum,

On top of the fuel pump there is a throttle position sensor , it may be that but I cant see any relation to the level of the fuel tank.
Air getting into the fuel lines will make it rev up before cutting out

if it uses a lot of engine oil id think about oil getting into the induction manifold and having a runaway engine for a moment or two. it can run on hot engine oil/mist if too much oil in the sump. I think there's a valve in the rocker cover that's supposed to stop that happening.

Someone else may have a better idea.

[MCGRAW80]

Welcome to the forum,

On top of the fuel pump there is a throttle position sensor , it may be that but I cant see any relation to the level of the fuel tank.
Air getting into the fuel lines will make it rev up before cutting out  

if it uses a lot of engine oil id think about oil getting into the induction manifold and having a runaway engine for a moment or two. it can run on hot engine oil/mist if too much oil in the sump. I think there's a valve in the rocker cover that's supposed to stop that happening.

Someone else may have a better idea.

Hi, thanks for the reply. It doesn't use a drop of oil between services and it's never once cut out whilst revving. It just keeps revving until I turn the engine off. How can I check to see if air is getting into the fuel lines? Cheers