2500S engine reluctant to start and barely runs.

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
Message
Author
Clifford Pope
Senior Member
Senior Member
Posts:954
Joined:Fri Mar 19, 2004 3:50 pm
Location:United Kingdom
2500S engine reluctant to start and barely runs.

#1 Post by Clifford Pope » Thu Feb 08, 2024 6:13 pm

This a Mark 1 which had a 2500S engine when I got it 2011.
I seem to have been plagued with engine problems ever since, or at least since Covid anyway.
It's always been temperamental, but was running quite well until 2019. Then came Covid, and also I was ill for some years, so the car was unused but I tried to keep things working. I started it every few months and got it up to temperature, moved it a bit inside the garage to keep the clutch free, tried the brakes, etc.
Now I have recovered my enthusiasm, and it won't start. It has new ignition parts from the Distributor Doctor, I drained the old fuel, flushed the tank, re-did the pipework with new new rubber connectors, but I flattened the newly charged battery but it didn't give even a cough or splutter. While recharging the battery again I checked the at the plugs, which spark well.
On trying again it finally almost ran, then picked up a bit, but it sounds awful, with a horrible harsh crackle in the exhaust like a boy racer, and cuts out if I try to rev it. It doesn't seem to be a weak mixture - pulling the choke out even a tiny bit causes it to stop instantly. It will rev, but misfires and bangs, and stops if I try to pull in first.

I left it for half an hour and tried again, but now it won't run at all.

Really I've run out of ideas. Can anyone suggest anything I should try (other than putting it on ebay with no reserve).

Charles H
Senior Member
Senior Member
Posts:1656
Joined:Mon Jan 15, 2007 2:38 pm
Location:Folkestone

Re: 2500S engine reluctant to start and barely runs.

#2 Post by Charles H » Fri Feb 09, 2024 9:07 am

Where are yo in the country? I am sure someone can help. If you have a good spark on all cylinders, I would firstly check for the correct firing order, 153624 anti clockwise as you look down at the distributor. Is the distributor loose so would have changed the timing? Then check for fuel supply to both carbs as a starting point. Good luck.
Charles Harrison
Register member 3095
Folkestone
Cherry Red Mk1 2000 Rally Car
Mallard Blue 2.5PI
Sapphire Blue GT6 Mk3
Vermillion Red Spitfire 1500
Pimento Red TR6
Inky Blue VW Passat B5.5
Silver Range Rover Vogue SE

johnnydog
Senior Member
Senior Member
Posts:1733
Joined:Tue May 14, 2013 12:33 pm
Location:Lancashire

Re: 2500S engine reluctant to start and barely runs.

#3 Post by johnnydog » Fri Feb 09, 2024 2:37 pm

I doubt it will be a weak mixture if the car was running well before covid, but now doesn't. Unless you have done anything else to the engine, those symptoms (to me) point to a carb issue. I'd take the tops off, clean, check the rise and fall of the pistons, the balance of the linkage, the cleanliness of float valves / bowls etc. Another Register member had similar issues on his 2000 with HS4s, and checking the above and a clean of the float valves as it was flooding on the front carb, a tweak of the balance of the throttle / choke linkages, and enriching it two flats (as it was clearly running a little weak) has made the world of difference.
Not saying this could be the the sole cause of your issues, but it's where I would be looking initially.
Stale fuel can cause all sorts of of issues even after being replenished with fresh fuel.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

Clifford Pope
Senior Member
Senior Member
Posts:954
Joined:Fri Mar 19, 2004 3:50 pm
Location:United Kingdom

Re: 2500S engine reluctant to start and barely runs.

#4 Post by Clifford Pope » Sat Feb 10, 2024 5:31 pm

Many thanks. That reinforces the thoughts I have been having after I posted my question, and also tried starting again. I'll check the carburettor items you suggest. This time it didn't bang and crackle like before, and it now does actually idle reasonably smoothly, but cuts out or misfires really badly if I try and coax it faster. If I can get past this enormous flat, or rather non, spot then it will run fast for a while, before suddenly cutting out. But if I then give it no throttle or choke it will re start instantly and idle again.

User avatar
valencia
Senior Member
Senior Member
Posts:189
Joined:Fri Aug 19, 2005 11:56 pm
Location:Lancs

Re: 2500S engine reluctant to start and barely runs.

#5 Post by valencia » Mon Feb 12, 2024 6:48 pm

Hi Clifford, I've only just seen this but a few years ago my 2000 idled quite well but was reluctant to rev and lacked power. It was all down to high resistance in the plug leads and the carbon brush, I don't know if you have made any progress but maybe worth a check, the leads should be 420ohms per inch max I believe, not sure about the brush though. A tuning establishment put mine on one of those sun testers, there were six traces on the screen, all looked quite good till the throttle opened and then they all dropped as the system could not cope with the increased electrical load, this was on a rolling road so under mechanical load as well.

Forkie
Senior Member
Senior Member
Posts:1017
Joined:Thu May 03, 2007 10:31 pm
Location:Cornwall

Re: 2500S engine reluctant to start and barely runs.

#6 Post by Forkie » Mon Feb 19, 2024 8:26 pm

As stupid as this may sound, i say that because i cannot even get my own 2500S to run correctly - it should be on SU HS6 carbs - have you checked the oil/oil level in the dashpots....low level /incorrect grade i believe will play havoc with starting/running issues.
Member Number 7392 04/07

1975 TRIUMPH 2500S AUTO ESTATE IN BRG!

DON'T TIDY UP - LEAVE IT WHERE IT FELL!!

poppyman
Groupie
Groupie
Posts:46
Joined:Mon Oct 31, 2016 5:51 pm

Re: 2500S engine reluctant to start and barely runs.

#7 Post by poppyman » Tue Feb 20, 2024 1:26 pm

<t>Hi folks, i have a similar problem on my 2500S... No problem starting but after approx 8 miles it starts to misfire and will eventually stop, and refuse to start until it cools down again. Not overheating 79 degrees.... The spark at plugs becomes very weak and at the points. even happens with borrowed electronic distributor. new coils new leads, red rotors, plugs,cap,point's,condensor etc..... starting to pull out what little hair i have left. Any suggestions Please. <br/>
This started when still running ballast. Now converted to run without and bypassed in loom ballast.... Drives really well until engine is warm. Thing of note it's an automatic, only done 56k and not messed with...</t>

Thanks, Tony.... Any ideas really welcome..

Forkie
Senior Member
Senior Member
Posts:1017
Joined:Thu May 03, 2007 10:31 pm
Location:Cornwall

Re: 2500S engine reluctant to start and barely runs.

#8 Post by Forkie » Tue Feb 20, 2024 8:20 pm

That to me sounds either coil or condenser. Something is not happy when it gets hot.Remember - just because it is new, does not mean it is right.
Member Number 7392 04/07

1975 TRIUMPH 2500S AUTO ESTATE IN BRG!

DON'T TIDY UP - LEAVE IT WHERE IT FELL!!

poppyman
Groupie
Groupie
Posts:46
Joined:Mon Oct 31, 2016 5:51 pm

Re: 2500S engine reluctant to start and barely runs.

#9 Post by poppyman » Wed Feb 21, 2024 9:48 am

I thought the the same, two different coils one new one off a running car. three condensers one off a running car and one electronic distributor to get rid of points and condenser again off a running car :roll: :roll:

Forkie
Senior Member
Senior Member
Posts:1017
Joined:Thu May 03, 2007 10:31 pm
Location:Cornwall

Re: 2500S engine reluctant to start and barely runs.

#10 Post by Forkie » Wed Feb 21, 2024 5:49 pm

I assume you have tried different ht leads and dizzy cap? So as this occurred before ballast conversion, it cannot be to do with that.
Member Number 7392 04/07

1975 TRIUMPH 2500S AUTO ESTATE IN BRG!

DON'T TIDY UP - LEAVE IT WHERE IT FELL!!

Post Reply

Who is online

Users browsing this forum: No registered users and 7 guests