[Rovernet] P5 running problem.

Sun May 17 15:06:43 EDT 2015

Good luck!
It is unfortunate when haphazard approaches seem to fix immediate issues.
The basics as I described catch many of those same things, and ensure 
that there are not other things coming up, one after the other, every 
day or week or trip, la dee dah.

FI, people keep talking about "coil overheating".
The prime cause of this is points gap incorrect, ie too close.
Besides cooking and eventually killing coils, this gives poor spark 
especially at starting speeds, but also at high speed or heavy load.
Too wide a points gap will give similar poor spark, but for other reasons.
Various other factors influence which is dominant in any given case.
So you have simple laziness causing numerous problems which may not be 
an issue NOW, but certainly will be.

Of course, when you change gap, you also change timing.
Timing is the most important single adjustment you can do.
It is perhaps not a good thing that the car will "work" after a fashion 
with timing wildly out, but it is sure to give less than stellar 
performance always, and dead engines often.

Fiddling with carbs can easily mask ignition errors, so that is another 
trap.
etc, etc, etc.
DO ALL of the BASICS FIRST ALWAYS!!!

FRM

On 5/17/2015 2:35 PM, peter king via Rovernet wrote:
> Thanks, Bill and all who’ve answered.
>
> I replaced a rotten vacuum line to the distributor this morning, installed a new fuel filter after the sediment bowl, and adjusted the carburetor for a richer mix, and one or all of those did the trick!  I think. I ran it for quite some time in the driveway, shut down and restarted with no problems. Acceleration without sputtering or backfire. I’ll do a road test later to see if it holds up for more than 30 minutes, but it’s looking good so far.
>
> I still have some slight irregularity at idle (occasional sputter or skip), but i checked the carburetor behavior with the piston lifter and it seems to be set right now—brief rise then falls back when the piston is lifted.  Exhaust is not visibly black, but does darken a paper towel when held in front of it for a while.
>
> Anyway, thank you all for your suggestions. I’ll keep you posted on the results of the road test.
>
> Peter
>
>   
>
>
>> On May 17, 2015, at 12:46 PM, magnet--- via Rovernet <rovernet at rovernet.org> wrote:
>>
>> Peter,
>>
>> You might want to try blowing out the fuel lines -- I had a somewhat similar problem (although not time-dependent) with my P4 and that was the culprit, specifically the pipe from the tank to the pump.  What is the layout of your petrol reserve: another pump, or an alternative feed in the tank?  Does switching to the reserve make any difference?
>>
>> Good luck!
>>
>> Bill D.
>>
>>
>>
>> On 17-May-15 10:08 AM, Alan Francis via Rovernet wrote:
>>> Peter
>>> Sounds very similar to my P4 90 problem. I was convinced it was dashpot oil which seemed to disappear as soon as I filled it (even though everyone told me "it can't" ) ran ok for a few miles then popped and banged relentlessly, even blowing a hole in the middle exhaust box, and, when checked, the dashpot oil level had dropped almost to nothing. In the end i replaced everything electrical, including the coil which seems have done the trick but still not entirely sure what it was, just relived I cured it!
>>> Hope you resolve your issues soon, it really is frustrating when these things occur and all the diagnostic logic of Mr Spock fails to make an inroad.
>>> Regards
>>> Alan
>>>
>>>
>>>       On Sunday, 17 May 2015, 13:18, Ben Saunders via Rovernet<rovernet at rovernet.org>  wrote:
>>>
>>>
>>>   Hi Peter,
>>> Not too sure if this will be of any help but some years back I had a
>>> similar problem that BP had been using 40% ethanol in our area.
>>>
>>> On 05/16/2015 09:32 PM, peter king via Rovernet wrote:
>>>> Update on the P5:  I ran it until it began to falter today, and checked the coil temp. Hot, but not excessively.  I checked the resistance across the coil and it was normal for the coil (3.3), checked secondary resistance, also normal. Checked voltage to coil with key on and with engine running at 2500 rpm, both ok.  I removed the sediment bowl to clean the screen and found it missing—probably dropped out when I removed the dome one night after stalling out on the road.  I removed the carburetor and cleaned it again, and will probably install an inline fuel filter to eliminate that as the culprit. But when I dismantled the carburetor, I noticed a lot of carbon on the inside. I also had backfiring at one point from the carburetor when I pushed the throttle quickly.  I’m going to check timing next, but any other thoughts on next steps?
>>>>
>>>> thanks for your collective wisdom.
>>>>
>>>> Peter
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>> On May 12, 2015, at 7:01 PM, peter king via Rovernet<rovernet at rovernet.org>  wrote:
>>>>>
>>>>> Thanks Steven et al,
>>>>>
>>>>> I’ll be checking this and all other suggestions this weekend, will let you know what I discover.
>>>>>
>>>>> Peter
>>>>>
>>>>>
>>>>>> On May 11, 2015, at 5:57 PM, Steven Dibdin via Rovernet<rovernet at rovernet.org>  wrote:
>>>>>>
>>>>>> Hey Peter,
>>>>>>
>>>>>> I have to second what others have said. This sounds like a classic case of an overheating coil. Try touching the coil when the engine starts running rough, is it hot to the touch? Do you have a ballast resistor on your system? Sometimes when they go bad they can let the full 12v get to the coil under normal running and overheat it. As with all things auto based, start with the easy to test and eliminate stuff first and work from there.
>>>>>>
>>>>>> Best of luck,
>>>>>>
>>>>>> Steven
>>>>>>
>>>>>> Sent from a small screen, please excuse any typing errors.
>>>>>>
>>>>>>> On May 11, 2015, at 17:37, Michael Connor via Rovernet<rovernet at rovernet.org>  wrote:
>>>>>>>
>>>>>>> PeterTry swapping the coil for a known good one. I have had more coil issues in recent years than ever before.This sounds like symptoms I had on my P4 except I could drive longer than 10 min. On my Morgan that stopped on a trip back from Houston one rainy evening and changed the coil along side the interstate.The coil worked fine and I got home with no other issues. A week or so later put the old coil back on and ran fine. It turned out there was a break in the wire from coil to distributor. Sometime it would make and sometime it would break.  This would be worth a check . Good LuckMike Connor
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>>>> Peter King
>>>> Peter King + Company
>>>> 21 Drydock Avenue
>>>> Floor 7
>>>> Boston, MA 02210
>>>> 617-292-7877
>>>> www.king-co.com
>>>>
>>>>
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> Peter King
> Peter King + Company
> 21 Drydock Avenue
> Floor 7
> Boston, MA 02210
> 617-292-7877
> www.king-co.com
>
>
>
>
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