Uneven revs

[Defender110]

Rubber primer bulbs have been known to get week and suck in to prevent fuel when under high demand then release again giving eratic fuel volumes?

[Geoffrey Gould]

Yep I can confirm the above from Defender 110. The non return valve in mine stopped working and the engine would tick over at full throttle and die. No pressure when priming.
G

[KevR]

Top left of the pump in your picture, two levers pivot on the same shaft (IIRC one is the cold start lever, one is the anti-stall). They should move independently, but they have a habit of seizing together. A bit of WD40 and move them about to free them, then a squirt of oil to keep them lubricated, may sort things out. Worth doing anyway.
I suspect an air leak's the more likely culprit in this case though.

[citronut]

air ingres will not make/cause the revs to go up, but would make it rattly/clatery,

its got to be adding fuel to bring the rev's up,

regards malcolm

[Dollywobbler]

Lots to explore. I have discovered that there is indeed a diesel leak, just below the driver's door. Parking can lead to it creating a right mess as the LHM leak is getting worse and I think it's dribbling engine oil too.

Malcolm - might be in your neck of the woods a week Monday if you're around? I think some expert advice might be handy. I am slightly concerned that this mobile leakage machine needs to get to Sussex and back next weekend!

[Geoffrey Gould]

Hi there are 2 rubber fuel pipes that join onto the metal pipes from the fuel tank end,just under the drivers door ( front of door, but can of course run depending which way the car is leaning.) They go to the fuel pump via. a fuel heater on the rear face of the block, to the primer - filter - pump and return to the tank.
The fuel heater can be by-passed without problem, in this country usually. They do leak and can be a pain. People that are worried about not having one can fit the later combined fuel heater and filter which bolts to the head, with the rubber primer bulb and dispense with the separate filter unit mounted to the body.
Cheers.
G.

[Dollywobbler]

This one has the fuel filter on the thermostat, which I presume was the new and improved way of heating fuel. I'll have a look underneath to see if I can spot the problem but it's a busy ol' week ahead.

[Geoffrey Gould]

Yep that's the later one, please try and have a look because if the pipe does let go or what ever it is, then you wont be going anywhere. Just a thought, it may be something as simple as a loose hose clip.
G.

[citsncycles]

there are 2 rubber fuel pipes that join onto the metal pipes from the fuel tank end,just under the drivers door

Both these pipes on Timex were perished at this point. One of them was easy to find a replacement for, but my local factor had to do some ringing round to find the other (the larger diameter one from memory).

[Dollywobbler]

Sod. That might be tricky to sort before the weekend. I can't think of any bodge that might work either. How long are these rubber pipes? Do they run all the way to the engine bay? It's currently raining so I'm unlikely to get under the car today. Might nip down to the local garage and see if I can blag a bit of ramp time though...

[mat_fenwick]

I'd be more likely to suspect the steel fuel pipes themselves, as in my experience they fail before the rubber ones (who do extend all the way into the engine bay BTW). These photos show the pipe run (the join to rubber at the front can just be seen on the first picture):

[Dollywobbler]

Thanks. It is indeed the metal ones, rotting where clipped to the body. Replacement pipework has been ordered.

The return has already been done by the look of it, though only a relatively short section has been chopped out with a rubber piece inserted. Seems a fairly standard sort of a repair. Will hopefully get the pipe replaced in the next couple of days. Much easier with a four-post lift!

[Dollywobbler]

New section of pipe fitted. What a messy job! Well worth paying £20 for my tame mechanic to get diesel all over himself and his floor. There's enough diesel soaked into my driveway as it is.

Naturally (and as expected) it's done nothing about the raising revs. Half an hour after getting home I restarted, didn't touch the throttle. Idle just below 1000rpm then shoots up to 2000rpm for a few seconds, then back down again.

[MULLEY]

A knackered injector?

[Dollywobbler]

Wouldn't that cause an issue all of the time though? This is a very specific incident. Leave it 10-30 minutes, restart and it'll be fine, then 2000rpm for a bit, then fine. Drive it 200 miles in a day and it won't repeat it. From a cold start, it's absolutely fine.