Pinking & Lumpy Part 2

[Peter Cobbold]

"The pinking is quite loud & banging as opossed to a rattling sound."

So maybe not pinking but backfiring in the inlets? or exhaust?

It might be misfiring on some strokes, leaving unignited mixture to light up in the exhaust and 'pop'. I'd borrow a coil that you know works on another car. You have checked the points havent closed up, which they can do in 100 mles if dry.

Check the 12v wires on the coil, to the loom and disy for a poor connection. I've had the supply lead from the loom fail at the connection between wire and connector, hidden under the insulation. And it failed while running, maybe from years and years of engine rocking.

 

Peter

Edited March 19, 2014 by Peter Cobbold

[Kevo_6]

"The pinking is quite loud & banging as opossed to a rattling sound."

So maybe not pinking but backfiring in the inlets? or exhaust?

It might be misfiring on some strokes, leaving unignited mixture to light up in the exhaust and 'pop'. I'd borrow a coil that you know works on another car. You have checked the points havent closed up, which they can do in 100 mles if dry.

Check the 12v wires on the coil, to the loom and disy for a poor connection. I've had the supply lead from the loom fail at the connection between wire and connector, hidden under the insulation. And it failed while running, maybe from years and years of engine rocking.

 

Peter

Hi Peter

Points have been checked, I have tried other coils but good point about a known working one from another car, i will try that. I will also check the loom cable to the coil and probably worth fitting a new connector on that.

Edited March 19, 2014 by Kevo_6

[whatmore179]

Kevo, Ive experienced the problem that Peter describes. I had a rocker arm break on me. Sounded like a injector had gone only firing on 5 whilst on load but OK on tickover. When checking the pulses on injector pipes would get backfiring with the unburnt fuel which you couldnt here that well with the bonnet down.

If all other enqs fail worth a look

Steve

[Kevo_6]

Kevo, Ive experienced the problem that Peter describes. I had a rocker arm break on me. Sounded like a injector had gone only firing on 5 whilst on load but OK on tickover. When checking the pulses on injector pipes would get backfiring with the unburnt fuel which you couldnt here that well with the bonnet down.

If all other enqs fail worth a look

Steve

Hi Steve

Thanks for your thoughts, everything's worth looking at the moment. I have already had the rocker box off but always worth another look.

I need to go through everything with a fine tooth comb.

[Peter Cobbold]

The only other thing I can think of that would cause a popping misfire is cross-firing in the disy. But its new, with new cap and rotor arm. Puzzling.

But as an experiment you could try grinding off the 'heel' on the rotor arm. It might be letting spark jump to the adjacent contact : 'cross firing'.

First make sure the rotor arm really fits snugly on the shaft.

Peter

[roy53]

condensor, cheapest things can fail.

Coil,as said try a known good one.

When you say you fitted new filter,did you been all of them e.g. in the metering unit connection,in the PRV.

 

With 106 psi what dose the gauge show when you blip the throttle and the miss fire start ?

 

Did you fit all of the parts you mention after the return from the international ?

 

I trust the rotor arm was one of the known good ones ? red

 

Roy

[Kevo_6]

Cheers Peter, I will try it on a spare rotor arm.

[Kevo_6]

condensor, cheapest things can fail.

Coil,as said try a known good one.

When you say you fitted new filter,did you been all of them e.g. in the metering unit connection,in the PRV.

 

With 106 psi what dose the gauge show when you blip the throttle and the miss fire start ?

 

Did you fit all of the parts you mention after the return from the international ?

 

I trust the rotor arm was one of the known good ones ? red

 

Roy

Hi Roy

 

Yes I have tried condenser & all strainers cleaned as you mentioned. I will check fuel pressures at various rev bands & throttle blipping and report back. Parts replaced after IWE = fuel pipes/filter throttle bushes etc.

Yes the red rotor arm.

Many Thanks

Edited March 19, 2014 by Kevo_6

[roy53]

Well Kevo you do seem to have a challenge on your hands, where is this pub you stopped at so we can avoid it ?

i would think that it's fuel starvation.When you drive and very slowly increase the speed dose all seem ok ?as on tick over you said it sounded fine.

If so then its a restriction in the fuel supply [ may be something in the tank ]or the pump isn't up to the job.

 

Roy

[Peter Cobbold]

Well Kevo you do seem to have a challenge on your hands, where is this pub you stopped at so we can avoid it ?

i would think that it's fuel starvation.When you drive and very slowly increase the speed dose all seem ok ?as on tick over you said it sounded fine.

If so then its a restriction in the fuel supply [ may be something in the tank ]or the pump isn't up to the job.

 

Roy

Yes - now we think its not pinking, running very lean would cause misfiring. The tank is well worth investigating.

Not much left now to investigate.

[jojim65]

Hi Kevo,

 

I'm no expert as you know, but happy to pop across next week for a coffee and work through a few things if you fancy, I'll bring my 6 so we can compare settings if you fancy....

 

Jim

[Kevo_6]

Well Kevo you do seem to have a challenge on your hands, where is this pub you stopped at so we can avoid it ?

i would think that it's fuel starvation.When you drive and very slowly increase the speed dose all seem ok ?as on tick over you said it sounded fine.

If so then its a restriction in the fuel supply [ may be something in the tank ]or the pump isn't up to the job.

 

Roy

 

Yes - now we think its not pinking, running very lean would cause misfiring. The tank is well worth investigating.

Not much left now to investigate.

Hi Roy

Increasing speed very slowly it seems smooth, foot down with any (small) load and the bad pinking thing.

 

Hi Peter

When you say investigate the tank do you mean for cleanliness or shall i try with fuel pressure gauge with various revs.

 

Is it worth increasing the pressure from the PRV or sending it to Neil Ferguson for refurb.

 

Many thanks to both.

[Guest ntc]

Kevo

there is a small filter in the prv if std.

[Kevo_6]

Hi Kevo,

 

I'm no expert as you know, but happy to pop across next week for a coffee and work through a few things if you fancy, I'll bring my 6 so we can compare settings if you fancy....

 

Jim

Hi Jim

 

You have a PM.

[Kevo_6]

Kevo

there is a small filter in the prv if std.

Hi Neil

 

It was you who got me to clean out the strainer filters in the PRV & MU last year when you were trying to get me sorted and helped me balance my butterflies.

I did check again last weekend when i replaced the fuel filter and the high pressure pipes and the pump/PRV cotton reels, it was very clean inside every where though.

Many Thanks

[Guest ntc]

Kevo

I hope Jim can help you one last thought have you checked the ground little brown wire in your rebuilt dizzy on he baseplate ?

[Kevo_6]

Kevo

I hope Jim can help you one last thought have you checked the ground little brown wire in your rebuilt dizzy on he baseplate ?

Cheers Neil, I will check the dizzy out.

[Peter Cobbold]

 

Hi Roy

Increasing speed very slowly it seems smooth, foot down with any (small) load and the bad pinking thing.

 

Hi Peter

When you say investigate the tank do you mean for cleanliness or shall i try with fuel pressure gauge with various revs.

 

Is it worth increasing the pressure from the PRV or sending it to Neil Ferguson for refurb.

 

Many thanks to both.

Revs at standstill wont replicate the fuel demand of an engine put under load while driving. (Tickover horse power are maybe 1-2hp or thereabouts, while opening the throttle fully at 2500rpm when driving gives roughly 70hp - and fuel flows follow horse power, so that's a ca 30-fold rise) If the feed is impaired you might well not see any effect on fuel psi on a stationary engine at all rpm. Can you measure pressure while driving? Or on a rolling road?

 

If the tank has been coated with a 'sealant' a piece of that might have broken off and be blocking most of the feed.

 

Have you tried using the 'choke' to enrich the mixture when you try to drive? If that reduces the popping and stumbling somewhat - it wont cure it - then fuel feed from tank may well not be an issue. In that case, with the ignition off, take the black plastic plate off the side of the MU and suck hard on the pipe to the manifold. You should see the cam follower - with its little wheels rise up. And then fall back as you stop sucking. I am thinking it might be stuck in the up position, which will prevent the MU responding to engine load. If that is the case fiddle it free, WD 40 etc, until it rises with sucking and falls after.

I cant see why it should go wrong - I found the PI to be very reliable. But we are at the stage of checking everything!

 

Peter

Edited March 20, 2014 by Peter Cobbold

[Kevo_6]

Revs at standstill wont replicate the fuel demand of an engine put under load while driving. (Tickover horse power are maybe 1-2hp or thereabouts, while opening the throttle fully at 2500rpm when driving gives roughly 70hp - and fuel flows follow horse power, so that's a ca 30-fold rise) If the feed is impaired you might well not see any effect on fuel psi on a stationary engine at all rpm. Can you measure pressure while driving? Or on a rolling road?

 

If the tank has been coated with a 'sealant' a piece of that might have broken off and be blocking most of the feed.

 

Have you tried using the 'choke' to enrich the mixture when you try to drive? If that reduces the popping and stumbling somewhat - it wont cure it - then fuel feed from tank may well not be an issue. In that case, with the ignition off, take the black plastic plate off the side of the MU and suck hard on the pipe to the manifold. You should see the cam follower - with its little wheels rise up. And then fall back as you stop sucking. I am thinking it might be stuck in the up position, which will prevent the MU responding to engine load. If that is the case fiddle it free, WD 40 etc, until it rises with sucking and falls after.

I cant see why it should go wrong - I found the PI to be very reliable. But we are at the stage of checking everything!

 

Peter

Thanks for you thoughts Peter, I will try the things you suggest (the list is getting long but very worth it). I have a set of boroscopes from my safe opening days (legitimate of course ) so i can have a good look inside the fuel tank. I think i am going to have another busy weekend. I will look into a rolling road locally as that may be useful as you suggest regarding fuel pressure.

[TR NIALL]

Open the Petrol Cap,undo the Fuel Feed before the Filter and Blow the Fuel back into the Tank either with an Air Line or by Mouth,you will hear the Fuel Bubbling in the Tank and if you had a Blockage that should clear it,it Worked for Me.

PS,Clamp the Rubber Hose first or you'll have Fuel all over the place.

[k_raven_smith]

Pm sent

[Kevo_6]

Open the Petrol Cap,undo the Fuel Feed before the Filter and Blow the Fuel back into the Tank either with an Air Line or by Mouth,you will hear the Fuel Bubbling in the Tank and if you had a Blockage that should clear it,it Worked for Me.

PS,Clamp the Rubber Hose first or you'll have Fuel all over the place.

Hi Nial. Thanks for the tip, I will give it a little blow in the morning. I,ve brought my

Boroscope home from work so I can have a good look inside the tank.

[TR NIALL]

It could be small particles of Rust or something else gathered around the Outlet Hole a good Blow may shift it.

[Steves_TR6]

Bits of **** in the fuel lines cause all sorts of problems.

 

On a previous thread I posted a picture of the tiny black dots of contaminant in my fuel injectors, coming from the rubber fuel lines being eaten by unleaded!

 

Not the case here as you have new lines, but rust in the tank maybe causing similar probs?

 

Mind you it sounds like a high pressure side problem to me.

 

Hmmm

 

Steve

[Kevo_6]

Hi

Well there is progress, I have her running better. I had a good telephone conversation with Neil Ferguson (very helpful chap).

Probably an accumulation of various problems all pointed out here on the forum. Looked in the tank and there was only minor corrosion and no bits floating around but could not see over in the corner where the fuel comes out so I then did as Niall suggested & blew through the fuel pipe, there did seem to be a bit of restriction and then none (i may of imagined this). Checked inside the dizzy, all OK. Found the low tension cable on the loom side a bit dodgy so I replaced that lucar. Started her up and a bit better so I did as Peter & Neil (NTC) suggested and loosend the dizzy and started her up, turned it till the revs got high and backed off a tad, went for a drive and much better. When I was nipping the clamp tight I checked the dizzy to see if it would turn and bu$$er me it did so I took the bolt out and the thread was completely stripped in the middle, strange thing is that it felt tight on the spanner.

I could not do any more as my head was giving me a bit of jip and got a bit tired but at last I am getting there.

So I think my next job will be to make up a piston stop as Stuart suggests and get my TDC and recheck the timeing.

When doing timeing by moving dizzy do you do it at 800 rpm or 2000 rpm?

A big thanks to all that are helping me, fingers crossed she will be ready for the New Forest Run.

THANKYOU :-)