Strange engine problems

[Heuer]

My Elan S4 has developed a most frustrating engine problem and I am running out of ideas so I wondered whether someone here may be able to advise me.

The car started backfiring massively and eventually stopped. It restarted but it did not want to idle and began misfiring again. Having nursed it back into my garage I did some checking and found the fuel filter bowl was empty so:

1. I used a Mity-vac attached to the plastic fuel line to draw petrol from the tank to confirm there was no blockage
2. Having dismantled the pump and found no obvious problem I sent it to Brian Buckland for overhaul. He found it worked perfectly but serviced it with new NRV's.
3. Pump back on car still no fuel in bowl
4. Bought a new pump from Paul Matty and the fuel bowl eventually filled
5. Car would not start and backfired massively
6. When removing the dizzy noticed the timing was 90 degrees out (at #1 TDC rotor arm was pointing at #3)
7. Reinstalled dizzy and reset timing but car will not start. Noticed fuel bowl now not full despite cranking
8. Cranking the engine with plugs out shows no oil pressure sometimes. Dizzy does turn though.

All this leads me to think there is a problem with the jack shaft - fuel pump, dizzy, oil pump all acting up. As I have never had one of these engines apart any suggestions as to what may be going on? Can anything associated with the jack shaft and its fittings cause such problems? There are no nasty noises coming from the engine which was re-built by Peter Day and only covered 6,000 miles since.

Many thanks in advance. Hope someone can offer support.

David

[twincamman]

ok sounds like the distributor clamp was loose and it allowed the distributor to rotate some ......go through the timing, set the cams up with the marks facing ....and put about 5 degrees on the crank pulley ..number one at compression stroke ..check the dist in correctly ...pull the plugs and put number one plug in the wire plug setting on the engine and slowly rotate the dist with the ignition on until you see a spark from the plug ....that ill satrt it then use your timing light ..or your condenser has gone to ground . In either case the procedure will be the same after you have removed the dist .ed

[Bud English]

I bet you'll find the shear pin for the distributor missing or sheared. I'm guessing sheared because the problem escalated from bad to worse, first allowing the gear to shift on the shaft (about 90 degrees), then spin on the shaft. No ignition, no oil pressure...no run. I had that happen on a Pinto engine in the 70's.

[john.p.clegg]

Could the chain/tensioner be loose enough for it to jump a tooth or so of the jackshaft sprocket?

John

[Bud English]

If it just jumped a tooth the oil pump would still be working. But then... 8. Cranking the engine with plugs out shows no oil pressure sometimes. Dizzy does turn though. Interesting

[vincereynard]

If the fuel pump, distributor and the oil pump are all effected, surely that indicates a problem with the shaft that drives them all?

First thing I would do would be lift the cam cover and ensure that the cams are turning and timed correctly. Then you cannot do any more serious damage. Honk the plugs out and check you have compression on all 4. Basic mechanical twirly bits then OK.

As you drove it home it cannot be a sudden "fatal" failure, like the shaft drive failing totally. Sometimes fuel sometimes not? Sometimes oil pressure sometimes not?

As you have indicated, something to do with the jackshaft drive. Remove fuel pump, is the shaft turning? If the fuel pump is new that suggests not.

[Heuer]

Thanks for all the replies. Timing has been set and checked using the #1 plug method. Car will not start but huge backfire this morning.

With the pump out I can see the jack shaft turning (and the rotor arm) but fuel supply is non existent with original pump which tests OK on the bench. New pump seems to be delivering fuel although I noticed the glass bowl was only half full at one point during cranking. I have installed a known working coil, changed the dizzy cap and tried a couple of rotor arms to no avail. This morning no oil pressure when engine cranked without plugs in although I had oil pressure yesterday. Dizzy was tight so can't think it moved of its own accord.

Now maybe the three things (fuel, spark, oil) are not related but it is a strange coincidence. The jack shaft is under no real stress so a breakage would be unlikely. It is as though it is moving about laterally so the pumps are coming off the cams and the timing is all over the place.

[rgh0]

The oil will sometimes not show a pressure when cranking and sometimes will so i would not consider that a problem. If you have pressure when it runs its ok

The fuel pump will normally have some air trapped in the bowl so that is not a real problem - the real test is do you have normal fuel level in the carbs

If it does not start and backfires and you have spark at the plugs, my first question is, do you have the timing 360 crank degrees out?

Possible that the plate that secures the original block cam shaft and prevents fore aft movement has broken or come off. This would affect timing by maybe 20 or 30 degrees and could cause a backfire but the movement possible would still mean the fuel pump and oil pump worked I think. You could easily check by seeing if the timing is stable at the setting under cranking

cheers
Rohan

[Chancer]

The oil will sometimes not show a pressure when cranking and sometimes will so i would not consider that a problem. If you have pressure when it runs its ok

The fuel pump will normally have some air trapped in the bowl so that is not a real problem - the real test is do you have normal fuel level in the carbs

cheers
Rohan

Sounds to me that the only problem is that the OP decided that the timing was 90? out despite the engine running correctly so moved all the plug leads or repositioned the distributor and now the engine doesnt run.

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

Editted, I'm sure the post originally said that the engine was running before the distributor was removed, if i imagined it then ignore the above.

[wotsisname]

would you consider the method used to check the fuel line to the pump to be definitive ?
I have no experience of them, do they generate significantly more suction than the mech pump is able ?

[nebogipfel]

..........The jack shaft is under no real stress so a breakage would be unlikely..........

I had a jackshaft break in a twin cam.

My distributor stopped rotating but I can imagine a scenario where a broken jackshaft might drive intermittently.

[rgh0]

I also had a jack shaft break in a twincam

But it was easy to diagnose as you could see the broken shaft thorugh the hole in the block that the con rod had made.

cheers
Rohan

[billwill]

Check that the plug leads are in the correct locations on the distributor cap.

[Heuer]

Sequence of events was like this:
Drove car 300 yds and huge backfires started. Engine stopped. Eventually engine re-started but i had to keep playing with the throttle to keep it running as I turned around and headed home. Managed to get it on the drive before it stopped again. Re-started with more backfires and I limped it into the garage. Thought about the problem for a couple of hours and went back to start the car but it would not run apart from the odd back-fire. I started with electrical diagnosis - changed rotor, changed coil, changed cap with no change. Fuel bowl was full during this. Following morning I decided to check on fuel supply and noticed the fuel bowl was empty after cranking so attached Mity-vac to plastic hose and drew off fuel with no problem. To make sure, I removed the tank and emptied the remains of the fuel into a container to check it was running clear. Fuel pump worked off the car but not on it. New pump did draw fuel. The Mity-vac has a suction gauge and it was drawing fuel at 2.5psi

When I checked the timing at TDC the rotor arm was pointing at #2 hence I decided to go back to square one by removing the dizzy, checking the points and making sure the gear was not broken.

Next job will be to take off the cam cover to see if the sprockets are still per spec.

[Mick6186]

It seems the only item common to the distributor, oil pump and fuel pump is the jack shaft. If the timing chain had jumped enough to put the distributor 90 degrees out the valves would be bent by now. Could the dowel pin for the jack shaft be broken so the shaft is turning intermittently due to the securing bolt providing some drive tension.