A reluctant Starter - Now Sorted by S & C

[revilla]

Hi Piers,

I think to get to the bottom of this, you (or somebody on your behalf) is going to have work back in a logical manner from the known facts. I can see from previous posts that you have already spent a lot of money on replacing parts which have turned out not to have been the cause in the end.

At the moment the evidence points to little or no fuelling during cranking for some reason. Even if the cranking enrichment was not enough I would still expect it to make some attempt to start with the odd cough and splutter. 

I think the first things you need to find out are:

1. Is it actually fuelling during cranking?
2. If not, is it a pressure or electrical problem?
3. What mechanism is leading to the problem found.

I think that, excluding the very remote possibility that all four injectors are simultaneously faulty in the same way, we can assume that if there is the correct fuel pressure behind that injectors and the correct electrical drive to them at the same time, they will be fuelling at least to the extent that it should make some attempt to fire after a number of attempts.

I was very careful to say at the same time in the previous paragraph, as it is quite possible that the fuel pump might prime the fuel rail to a good pressure but then not switch on during cranking, allowing the pressure to fall off before the engine starts (e.g. with a poor crank sensor waveform as Arnie was suggesting earlier).

To answer these questions I think you need:

1. A fuel pressure gauge plumbed into the upstream end of the fuel rail, and
2. An oscilloscope (or at a push, a digital voltmeter but that will give you a lot less information) connected to one or more of the injectors.

These are probably not things you have access to yourself. I understand that the car is booked into Sevens & Classics shortly. It may be a good idea to point them towards some of the discussions and conclusions in this thread as a lot of people have put some considerable thought into your problem and would really like to see this resolved for you.

I know they previously found that engine loom to chassis loom connector to be corroded and cleaned things up, but having looked at what that connector carries I cannot see how a poor connection there could lead to symptoms which match yours; I may well be wrong, but I think it is important to keep an open mind and trace the problem through step by step until it is properly understood before jumping to conclusions, especially with a problem like this that every now and again seems to disappear, giving the false impression that the last thing tried fixed it.

Good luck with Sevens & Classics and please keep us posted.

Andrew

[Piers300]

Revilla.  Thank you for your comprehensive efforts in helping to pinpoint my starting problem. It is very much appreciated by me.

Yes, it is going to Sevens and Classics for them to have a good look at this week. They can start it from cold and hopefully find the problem. Last year was a wash out for me with the 7 and I only used it for the IoW Blat (where the starting problem happened again -  third year in a row) and one local 7 meeting where it failed to start, so very frustrated in lack of use.

As you correctly assume, I do not have a pressure gauge to test the fuel pressure, but I do have a digital Fluke 87 meter. This problem is beyond my technical abilities to sort, so it will be S & C and their techniciains who can hopefully find the issue.  I don't have an oscilloscope though but could get access to one via my radio club that I am a member of.

Right at the start of the problem, I did suspect either the Toad alarm system or the in tank fuel pump. Being hard of hearing, I could not hear the pump, but my wife could. When it had a 6000 mile service by Chapman Cars, they got a spare fuel pump in, but did not change it, as they tested the existing one and said that was fine. So, I have been looking elsewhere for the problem since. As you say, the bill to date has been rather high and I have a very good spares kit !

Many thanks for your advice and guidance and I will let you know the outcome, once S & C have had an opportunity to have a look at it.

Piers

 

[Piers300]

Update: The 7 is back and I picked it up from S&C on Thursday. In the end, they found the problem.

Sevens & Classics have had it for 13 days, so time to see the starting issues, that sure enough raised their head, after they thought they had fixed it. When I got there, it was cold and started on the button.

They say that initially, they thought it was T/B's and TPS adjustment, which they set up and left it. It started the next day, but failed to start the day after so they knew that was not the issue.

What they found was a faulty earth connection for the ECU and this wire went via the 14 multi pin connector, which was the item that we previously thought was causing the problem. The earth for the ECU had been terminated onto a screw that was on some module that was bolted to the scuttle direct in front of the ECU ( I think it is the altitude compensation unit). They rewired the earth to a new position onto the chassis and it started every day at S&C for 3 days without issue. They are confident that was the problem.

I have to say that the cost for doing it was a very reasonable £173 in total. They fitted new spark plugs and set up the Roller Barrels and TPS. So if that is it, I am a happy chap. So thank you S&C for your help.

So this morning, bright and early, I had arranged to meet some Kent 7 Club members at Charing Hill. The car started on the button and restarted every time it had to. Hopefully, the problem is now sorted and that was the first blat for probably 18 months and very enjoyable.

I am now looking forward to the summer.

Piers

[SM25T]

Good news. Earths have a lot to answer for !

[John Vine]

Excellent news, Piers!  And well done, S&C.  Let's hope your starting problems are now permanently resolved.

...and this wire went via the 14 multi pin connector,...

Are you sure about that?  It doesn't appear to accord with Andrew's analysis in post #215.

JV

[Piers300]

Hello John

That is what S&C told me about the multipin connector and the earth.

I have to say I am delighted to have the car starting and todays blat was great.

As you say, let's hope it's a permanent fix.

Thank you for all your help in trying to diagnose to problem.

Piers

 

 

[Martin J]

Good to hear all is well Piers. Takes me back to when I was building my car & it refused to start. That proved to be a bad earth. 

Hope to see you on a blat soon, although they don't seem to be posted on blat chat anymore. 

[Piers300]

Final update. Recently back from a tour of the Cotswolds and Malvern Hills including being parked all night in the pouring rain outside the hotel. Six Sevens in total on this three day trip , including a visit to the Morgan Car factory, where we were given our own tour guide. The car did not miss a beat and started on the button every day. Thank you S&C.

Thank you to everyone who helped.

 

Piers

 

[JNC]

It's a good feeling knowing when you turn the key it springs to life !.

[Piers300]

JNC. You are right. I have to say that I lost faith in it being able to start and therefore would not use it, as chances were, it would not start when needed. Those worries are now behind me.

Piers