Engine ignition troubles

ChrisJC · Post by **ChrisJC** » Mon Sep 16, 2013 9:23 pm

Years ago (when I built that engine in fact), I tested all the injectors myself. I knocked up a fuel rail (mower petrol can, pump, fuel pressure regulator) with an injector on it pointing into a bucket. Power the injector via the resistor pack, and see what comes out. I screened quite a few into the bin!

Just be careful with the sparks from the hokey wiring and the petrol vapour!!!

Chris.

v8alligator · Post by **v8alligator** » Thu Sep 19, 2013 11:24 am

Hi Chris,

I have checked the fuel regulator and am getting 42psi with the vacuum disconnected and 28 - 32 psi with the vacuum plumbed in.

I have removed the fuel rail and using a resistor pack and a bit of wiring have been able to get the injectors to fire.

To be honest all the injectors are working but it is difficult to tell if the spray pattern is acceptable.

I am going to change the fuel pressure regulator for the uprated type when it arrives to see if that improves things.

DaveEFI · Post by **DaveEFI** » Thu Sep 19, 2013 1:00 pm

42 seems high to me. 36-38 is what I usually see. However, the slight richening of mixture this causes is unlikely to cause a miss-fire.

Normal quick check of injector pattern is a brief burst onto blotting paper and check for an even pattern.

v8alligator · Post by **v8alligator** » Wed Sep 25, 2013 12:04 pm

Hi All,

I have had another week of testing to try and sort my hesitation when off tick over.

I have fitted the new fuel pressure regulator and set it to 3 bar with no vac connected. This has improved things considerably but is still not 100%

I had already changed the rotor arm, cap, plugs and leads but decided to look at the ignition again. I have removed the ignition module and tested it through its rev range. The test showed the module was breaking down under load. New Lucas one fitted and it has transformed the starting and response from the engine.

But there is still a hesitation and I think the engine is now running rich. I was going to adjust the air bypass screw on the AFM this weekend to see if that sorts things.

Reading an articular on the web there seams to be 2 methods on adjusting the CO, one is to adjust the bypass screw at ideal and the other is to remove the cover and adjust the workings inside. Has anyone done either of these and with any success?

Also is anyone running a Power Spark Distributor? I have one fitted to my 88" and we have them in 2 other V8 land rovers and they do not seam to be very reliable. They were all fitted at the same time and todate we have swapped the rotor arms and caps on all 3 and now a ignition module due to failures.

Would be interested to hear if anyone else has had problems?

DaveEFI · Post by **DaveEFI** » Wed Sep 25, 2013 1:01 pm

The BL manual for my flapper says 36 psi vacuum disconnected. Not sure what the figure is for the hotwire.

There's been some comment on the SD1 forum about these new cheap repro dizzies from Ebay - and none of it good. Amps seem to fail quickly, and other bits too. The warranty seems to be 1 year for the dizzy, but only 90 days for the amp which sort of says it all.

This is a quote from one post:-

I bought one ..... ages ago and it was absolute rubbish, didn't last long as it managed to fill itself with oil, amp on the side packed up after just a hundred or so miles and the screws were made of cheap crappy metal.

ChrisJC · Post by **ChrisJC** » Wed Sep 25, 2013 5:27 pm

The AFM is not supposed to have the cover removed and be adjusted. The bypass screw should be all you need to set the mixture (along with the idle speed screw on the plenum), provided the throttle levers are set correctly (i.e. butterfly fully shut at idle)

In the past, I have fiddled with the AFM spring tension, but more to alter the running mixture than the idle.

My experience of ignition amplifiers and coils is that the correct (i.e. OEM) amplifier and the matching Bosch coil will last. Mixing and matching is doomed to failure!

Chris.

v8alligator · Post by **v8alligator** » Tue Oct 15, 2013 11:42 am

Right after loads of testing and checking I have finally found the problem.....

I went back through the entire EFI system using the Land Rover Test process and can confirm there is nothing wrong with any of the EFI system or fuel system including injectors. All are giving the correct readings and the engine runs better then ever now the CO and airflow meter have been adjusted correctly.

I thought the engine fault was a missfire but its not. The engine is simply bogging down under low revs. Once the engine passes 1250rpm it is perfect loads of pull and does not miss a beat.

After reading lots of bad reviews on the power spark distributors I decided to pull mine apart and see if there is any thing amiss.

Low and behold what a badly made piece of kit! The bob weights are very poorly manufactured, they are formed out of 2 plates riveted together and the rivets are not flush so jam and catch on the base plate hindering there operation.
The springs are way to heavy and I can not get the weights to move by hand.
The spindle shaft is not very well machined and the castellated pick up looks like it has been filled by hand rather then machined in.

With all this in mind I have ditched the PowerSpark dizzy and have gone for a standard Lucas 35dml8 one and what a transformation. The engine is responsive no hesitation, bogging down or mess behaving.

Hopefully I will get more then 125miles out of this one.

Thanks for all the help and suggestions offered.

ChrisJC · Post by **ChrisJC** » Tue Oct 15, 2013 6:03 pm

Aha, the aftermarket strikes again!!

Chris.