Pinking & Lumpy

[Kevo_6]

On the way back from Malvern to Poole, about 25 miles from home we stopped for a Pub lunch, the car never missed a beat until we left the pub, then it started pinking under load and running lumpy on tick over. Where would I start to look or is it a case of checking injector cones and then the ignition parts one by one. I have re-con DD dizzy and a re-con MU & injectors from Neil but still running on the original Lucas pump etc. I have not looked at anything yet as I was hoping to get a few pointers first.

As always, I look forward to all of your comments.

[littlejim]

In view of a recent personal experience I'll ask - 'did you happen to buy any petrol after leaving Malvern?'

[Kevo_6]

Yes i did, that did cross my mind, i was on a half a tank and filled up.

[Peter Cobbold]

I'd suggest its heat-soak in the fuel system somewhere when parked up hot. Vapour lock. Check first to see if the lumpiness has gone when the engine is cold.

 

Vapour lock is not uncommon with present fuels, its . The nylon injector hoses are in a hot place when a hot engine is switched off, so that's where I'd start checking for pulsing.

[Guest ntc]

I would check tank venting and electric supply to the pump. filter?

Edited August 12, 2013 by ntc

[Kevo_6]

Many Thanks Jim, Peter & Neil.

 

Some good pointers to start with.

 

Neil one of my next planned jobs was to re-cable the pump via a relay, i think that maybe No 1 on the list now.

[Steves_TR6]

My bet is with Peter, heat soak.

 

Check the pulses, it's the easiest place to start.

 

Any injector not pulsing needs a bleed.

 

I found that my braided hoses have a bleed hole built in, just loosen the injector nut a little.

Otherwise point the injector into a receptacle, I use a small white plastic bucket, then with the engine running gently ease open the injector.

Keep the injector higher than the MU, so the fuel 'fills up' the hose then the injector then it works again :-)

Edited August 12, 2013 by SDerbyshire

[RogerH]

Along with the heat soak it may be worth swapping the coil & dizzy capacitor (condensor) for known good ones.

 

Roger

[Kevo_6]

Cheers Steve & Roger, will do.

[Steves_TR6]

Oh yes, if you have a condensor / points that's worth a check.

 

I once spent days and hundreds of pounds trying to track down erratic running on a petrol V8, in a boat, only to eventually find an intermittently faulty condensor

[Guest ntc]

If you read Kevo's post they will not be an issue

[Kevo_6]

I have checked all of the injectors and all have a good cone spray, replaced all plugs and swapped the coil. Still the same (running lumpy). I will run a temporary cable via a relay to see if that makes a difference and also will check the tank venting. One thing i have now noticed (heard) is a tapping sort of crackly noise coming from around the number one end of the engine at sort of valve height, does not seem to be pinking as this time not under load. Its not always there through the rev range only at first and then OK as revs increase. If I just blip the throttle it is there. I am now getting worried thinking its a stuck or badly seating valve. Or is it something more sinister?

 

Bu$$er I am now getting depressed

[Peter Cobbold]

I wonder if the pinking you described after leaving the pub was a tappet clearance opening up? That tapping noise you now hear from around #1 might be from a tappet adjuster that has unscrewed itself. I had one do that once, many years ago. Will be obvious with rocker cover off, and simple cure.

[Kevo_6]

Yes cheers Peter, I was just thinking of removing the cover to see if there was any thing obvious. Tomorrow evenings job I think.

[jamesStag]

hi Kevo,

Yup I agree with Peter. If you've got an odd noise turning up now also, then get the rocker cover off and have a look. Only takes a few mins (though I realise might disturb an otherwise good rocker cover gasket)

 

If everything looks OK, nothing apparently amis. I always think is worth running up the motor at tickover (as long as all pipe and cables out of the way). at low speed there's not much oil splashing about and you can easily hear or observe if anything is out of the ordinary.

 

Best of luck and I hope its not expensive. odds on to me I don't thinks its likely to be...

Cheers,

J.

[Kevo_6]

Cheers James, will do.

[Kevo_6]

Just a thought, I have stopped using valve master for the last couple of tanks full of fuel. As I had read a lot of posts suggesting our cars do not need it, and it did reduce the nasty fumes.

 

Is this another contributing factor?

[Peter Cobbold]

The ferrocene in Valvemaster would add a bit of octane, so if the engine pinks upon sudden acceleration that might be the cause. But there are better octane boosters.

 

I cant see loss of Vm contributing to lumpiness or tappiting from #1.

 

BTW a large screwdriver held to the temple by the ear is very useful for locating sounds, just keep the HT away from it.

[Kevo_6]

Thanks again Peter.

[Kevo_6]

I have removed the rocker cover, nothing out of the ordinary visually, adjusted tappets , some were a little wide also checked the timing and adjusted slightly. The engines starts OK and ticks over nicely when warm. When increasing revs slowly it sounds OKish. When blipping the throttle there is quite a bit of induction noise and then sometimes a sort of slapping sound. I think the slapping sound seems to come from the throttle bodies or the air box so i removed the air cleaner hose and blipped the throttle again and heard a sort of back fire in the air box. Still runs lumpy when driving. Having some cable delivered tomorrow so will try the new supply feed for the fuel pump and check the fuel filter etc.

I suppose after that i will need to do a compression test, is their any other things I can look for or do?

 

Thanks for everyone's advice so far.

 

N.B. Also there was a fair bit of sludge & condensation in the top of the rocker cover but not covering anything else.

[Peter Cobbold]

Try new plugs. A dodgy plug can cause backfires. And ferrocene in Valvelamster can cause them to short. You might still be lucky!

And clean around the disy cap just in case its cross-firing there.

 

Then compression test as you say.

[Guest ntc]

Insufficient fuel pressure, as I asked filter? including the one in the prv valve

[Kevo_6]

Peter, I have put in a new set of plugs and checked dizzy cap etc.

 

Neil, I have also got a new fuel filter coming tomorrow re your previous suggestion and thanks for suggesting the PRV, that's a strainer type i think similar to the feed in the MU?

 

I really appreciate your help on this.

[Guest ntc]

Correct and it was not hot enough to get fuel problems at Malvern

[Kevo_6]

Cool