Strange engine problems

[Orsom Weels]

I was reading through the symptoms described & kept thinking either broken jack shaft, I can remember John having one break many years ago for no apparent reason, or sheared/missing dowel in the drive gear. I can't for the life of me think what would cause the dowel to shear, even if the securing bolt wasn't completely tight, but if it was omitted during the rebuild & the bolt tightened enough to grip the sprocket to the shaft, it is possible that after 6000 miles it has become loose enough to allow the sprocket to slip intermittently, as Mick6186 suggests. The tab washer would stop it undoing completely.
Try re-checking/setting the distributor timing, make sure you know exactly where it is, then, if after trying to start the engine it starts to back fire again, re-check the timing to see if it has moved. If it has, you will know that something in the drive train to the distributor is amiss, it will then just be a case of narrowing it down, there's not too many things it could be.

[Heuer]

Some progress. Based on the comments here (thank you one and all) I retraced my steps and discovered the brand new dizzy cap I installed was, in fact, faulty.Two of the HT lead holes in the plastic were not deep enough which meant the screw in spikes were not going into the cable cores. A light tug and the leads dropped out. I put back the 'old' cap, reset the static timing and the engine started - briefly! It ran really rough for about 10 seconds and then died. Tried a second time with the same result. I am basically back to the way it was when the problem first appeared. But at least it is some progress and on the positive side the oil pressure came back.

Looks like the fuel pump is not working.

[Chancer]

Number one rule of faultfinding, dont panic, keep it simple, ask yourself what was the last thing that was worked on or changed?

Rule number one point five:

Only replace a part definitively if you are sure that it is faulty, if the fault remains especially a starting problem like this one remove the new part and refit the old as you could well have introduced a second fault.

To be fair this wasnt a rule in the good old days when a new part was 95% certain to be functional and an old second hand part less likely, now its the other way round.

When I read that you had replaced ingnition parts I began to worry.

Hope you find the problem soon, I have a small lawn mower fuel tank which I run my elan engine fromevery couple of years because the main tank is rusted, something similar can be used to diagnose if you have a fuel pump problem.

Did you say that the pump was repaired by Brian B? If so then its probably an air leak on the suction side, blocked filter or maybe just needs priming.

[Heuer]

Pump was checked by Brian and he declared it OK but changed the NRV's as a precaution. Once re-fitted it did not work so I bought a new glass top one from Paul Matty. Initially this worked but the fuel bowl is currently only half full. Engine stutters, backfires and dies - not sure if it is fuel starvation as yet.

[richardcox_lotus]

Are you absolutely sure there is no debris in the fuel line from the tank to the pump.

It sounds like there is some residue moving around.

Regards
Richard

[Heuer]

I thought that so I:
a) removed tank an swilled around a couple of litres of fuel and dumped it into a closed vessel for inspection
b) used the Mity-vac to draw fuel, Hermetite solvent, MEK, and isopropyl alcohol through the fuel line followed by petrol
c) drew fuel using mouth suction and it was easy to get fuel into the line

My worries were using Hermetite on the fuel sender gasket and red rubber grease to ease the filler neck rubber. could cause a blockage. Neither are soluble in petrol but my tests suggest a bit of agitation means they do dissolve.

[vincereynard]

Can you rig up a small tank to feed the carbs by gravity?

PInch a fuel tank of someones moped!

At least eliminate one potential problem.

[JC33supreme]

Just to confirm that the jackshaft definitely can break - happened to me in my first Elan (that would be over 40 years ago). Good luck sorting your problem.

[AHM]

From the boot
Remove the fuel line from the tank - Blow down it to check for leaks (it is normally suction pressure) if a puddle appears you have found it.

next pump fuel through it until the carbs fill, valves close and you get back pressure (you can ignore the fuel pump)

start the engine if it runs ok for a short while you have a fuel delivery problem.

Continue isolating things methodically

[Orsom Weels]

6. When removing the dizzy noticed the timing was 90 degrees out (at #1 TDC rotor arm was pointing at #3)
David

I think you need to find out how this happened, if, as you've said, the distributor clamp was tight & the body had not moved, the cause could only be a sheared pin in the distributor drive gear or the jack shaft has moved in relation to the crank/cam shafts. Regardless of any other issues, this would be my main cause for concern.
Regards, Tim

[Chancer]

Being pedantic "when removing" means in the act of removing, it could well be that the distributor was partially withdrawn from the bevel gear when the assumed misalignment was noticed which would be completely normal.

The following was very good advice if the OP remains convinced that something slipped.


Try re-checking/setting the distributor timing, make sure you know exactly where it is, then, if after trying to start the engine it starts to back fire again, re-check the timing to see if it has moved. If it has, you will know that something in the drive train to the distributor is amiss, it will then just be a case of narrowing it down, there's not too many things it could be.

[nebogipfel]

I think you need to find out how this happened, if, as you've said, the distributor clamp was tight & the body had not moved, the cause could only be a sheared pin in the distributor drive gear or the jack shaft has moved in relation to the crank/cam shafts. Regardless of any other issues, this would be my main cause for concern.
Regards, Tim

I agree. Your timing suddenly so far out would cause loud bells to ring in my head!

Fuel starvation tends to cause no firing rather than backfiring

[twincamman]

Could it be you have mixed up the plug leads In your distributor or you have the firing order wrong ? Of course there is gas in the tank ....I spent some time with a nostart situation because I didn't believe the gas gauge ..CHECK THAT THE DIST DRIVE IS NOT OUT A TOOTH the rotor must point at number one in the cap at TDC prove this by setting the cams and crank pully at tdc on power stroke and sparking number one plug .it really sounds like a mis set distributor to me ?or in desperation set the cams timing marks to the outside on the head spark number 4 plug and see if your 180 out ?1..3..4..2?.clockwise ?.Ed

[Heuer]

I took to heart the comment about making too many changes to the car and have gone back to square one. Leads have been checked and they are in the correct order in the old and fully functioning dizzy cap. There is fuel in the tank. Regarding the rotor arm being 90 degrees out I am wondering whether I noticed that, as someone suggested, after pulling it out! Been tinkering with the car for so many days now it is all merging into one and you begin to doubt yourself.

Something I did notice whilst setting the timing today. When I put my finger in #1 plug hole whilst rotating the crank to TDC I could not feel any pressure although I did hear some hissing. The n/s #4 cam lobe is pointing towards the centre so I moved on. Thinking about it in retrospect (and over a glass of wine) I am wondering if the hissing was from a valve rather than leaking past my finger. Would a compression or other test identify this? Maybe a burnt valve or the timing has slipped on the intake cam. I learnt the lesson that diagnosis is better than diving in and stripping bits off the car

[twincamman]

the finger will be blown off the plug hole when the correct stroke is found ?there will be no quuestion ?thenset the dist in the correct gear with the rotor at number one about 11 oclock just before number one on the dist spark the plug [ with the dist body serial number and flat spot facing the block ]?if your 180 degrees out just use number 4 as number one ?.I have done that before and the engine runs fine .ed