3000S Not starting when hot

[nwarner]

Since I've owned my 3000S it has never started when hot. I have always assumed it was petrol evapouration. The only real inconvenience has been filling up with petrol which I have always done while the engine is cold. Last week I managed to stall it at some traffic lights after getting some muck in the carb. and I had my wife with me. She wasn't pleased sitting in the road at traffic lghts for 20 minutes with everyone trying to get round me and said it was about time I sorted it out. To check if it was fuel I rigged up a feed from a can to the pump away from heat and warmed up the car. The result was it still wouldn't start. I checked for a spark at the plugs and no spark. I have tried a new coil, new ballast resistor (both tried while it was still hot and still no spark). I have replced the points with an Accuspark ignition and still the same. To double check I have swapped the coil,ballast resistor and ignition module with my Reliant Scimitar and the Scimitar still starts fine when hot but the problem persists with the 3000S. The car runs fine before stopping. Has anyone any other ideas?

[ausi steve]

I suggest you check your entire ign wiring. When driving & the engine is hot the voltage in the system is 14.2 volts.As the car/system heats up so does the resistance in the connections, resulting in voltage drop. Whilst the engine is cranking on the starter, the available voltage of the system can drop to around 10 volts. Combine this with the loss of voltage due to bad connections & the result is not enough voltage to allow the ign system to provide a spark. Also ensure that the earth connections are also clean & tight.

[bluezeeland]

Nigel, for starters, the lt and ht wiring, set pre-ignition, check mechanical and vacuüm advance of dizzy, check vacuüm hoses to carb and pcv valve, check pcv valve itself, make sure carb is ok, get new packing set for carb, frank

[phillpot]

Not saying it's the problem but I'd junk the ballast resistor and get a 12 volt coil, keep things simple!

Know its meant to help cold starting (or starting in cold weather) but mine fired up no problem all through last Winter without it.

[nwarner]

Thanks for the replies.

I've already checked all the ignition & earth connections when I had a problem with the ignition switch so I think they are OK. Last night I put on a new set of ignition leads to try even though the old one are less than a year old but no change. The vacuum hoses are all fine. The vacuum advance is diconnected as it doesn't work. I'll swap the PCV valve with my Scimitar to see if that's the problem. I'm also going to try running an earth to the distributor to see if that makes a difference.

[Adrian@]

Hi Nigel ..I'd go with vac timing issues 1st, but, does the carb close it's self down when you turn the idle screws fully in? (visually set/mark these and return them to the same position as they were) check each side separately (your looking for un-metered fuel here).
A test of the system when hot ...remove the start relay and the double OE connection on the ballast (this is 12v IN whilst cranking from the starter and link wire to the coil) THEN (still with the ballast), you should have the 12v live AND your ignition system on the other end, remove them from the ballast and test for 12v when you have the ign switched on, go back to the 12v IN and link, you should have 12v whilst cranking, readings must be taken with the ballast out of the system.
Adrian@

Edited by Adrian@ on Thursday 19th July 09:37

[bluezeeland]

Nigel if not already check all settings and eventually recondition carb, burton does he set. At least the fuel-air side of things should then be ok. Reinstate the vacuüm piping, fiver or thereabout for new hoses and t-pieces, and check their actions. If unclear may i suggest t he haynes capri guide. Please let us know how you fare

[nwarner]

Adrian@ said:

Hi Nigel ..I'd go with vac timing issues 1st, but, does the carb close it's self down when you turn the idle screws fully in? (visually set/mark these and return them to the same position as they were) check each side separately (your looking for un-metered fuel here).
A test of the system when hot ...remove the start relay and the double OE connection on the ballast (this is 12v IN whilst cranking from the starter and link wire to the coil) THEN (still with the ballast), you should have the 12v live AND your ignition system on the other end, remove them from the ballast and test for 12v when you have the ign switched on, go back to the 12v IN and link, you should have 12v whilst cranking, readings must be taken with the ballast out of the system.
Adrian@

Edited by Adrian@ on Thursday 19th July 09:37

Hi Adrian

I've carried out all your checks and every thing checked out ok. I aslo ran another earth lead to the engine. I took it out for a run and just before I got home it cut out. It started then cut out. Managed to get it back on the drive when it cut out again and now won't restart. I put a lead from the battery to the ballast resistor as you suggested before when I had cutting out problems and it started fine and ran well. I put it back to normal and it started and cut out and then wouldn't restart. I decided to take the starte relay off and take it apart. The points were badly burned and one of the wires from the coil was also showing signs of burning where it used to be attached. I've cleaned everything up and soldered the coil wire back on and it now starts and runs so I think this could have been the problem of the cutting out. I've been to my local motor factors to try and get another but they only have one that is fitted to an MGBGT that looks similar but the diagram on the top is different. Do you know what one I need as since taking it apart I can't get the cover back on.

Regards

Nigel

Edited by nwarner on Monday 30th July 09:17

[bluezeeland]

Nigel,

Update please, very interested

rgds

Frank

[nwarner]

Frank

Not sure if it was the extra earth or replacing the starter relay but it now starts fine when hot. All I've got to do now is to sort out the misfire which is the down to the carb. If I strip it down and blow out the jets etc. with an air line and then put it back together it runs well for about 20 miles or so then starts misfiring again. I've got a filter right next to the carb. so I don't think much muck if any is getting beyond that so there must be something stuck in the carb. that I can't get rid of.

Regards

nigel

bluezeeland said:

Nigel,

Update please, very interested

rgds

Frank

[Adrian@]

Hi Nigel,
I have been away and had all new software on everything we own...
Re the relay .....any good quality relay should be good to buy. if you get stuck, get in touch.
Adrian@

[bluezeeland]

Hi Nigel,

Glad you got the hot start issue resolved,

Do think Adrian is a far better guide in this one, but is sounds like there could be something wrong with either the anti-stall diaphragm, or the choke/its settings.
Dont know if you got the haynes capri guide, the engine part is a good read, and can bring some good advise.
Have noticed in a number of threads that the carb is overlooked, maintenance-wise, i dont think a new gasket/diaphram/valve and jet set (about £30) is over the top, and at least you got the air/fuel part of the ops in order, obviously with all necessary tuning.

Kindly let us know how you fare

brgds

Frank

[nwarner]

Thanks Adrian

The local motor factor let me try the MGB one and it worked fine.

Thanks

Nigel

Adrian@ said:

Hi Nigel,
I have been away and had all new software on everything we own...
Re the relay .....any good quality relay should be good to buy. if you get stuck, get in touch.
Adrian@

[nwarner]

Hi Frank

I fitted new diaphragm and gasket set at the weekend and it didn't make any difference. There's obviously some muck stuck somewhere in the carb so I think it's just a matter of getting rid of it. I had a few problems last year when one of the fuel hoses started breaking up on the inside and the bits got into the carb. so I suspect one of these bits is still stuck somewhere. I'm going to strip the carb. down again and bring it into work and put it through the sonic cleaner to see if that will solve it.

Regards

Nigel

bluezeeland said:

Hi Nigel,

Glad you got the hot start issue resolved,

Do think Adrian is a far better guide in this one, but is sounds like there could be something wrong with either the anti-stall diaphragm, or the choke/its settings.
Dont know if you got the haynes capri guide, the engine part is a good read, and can bring some good advise.
Have noticed in a number of threads that the carb is overlooked, maintenance-wise, i dont think a new gasket/diaphram/valve and jet set (about £30) is over the top, and at least you got the air/fuel part of the ops in order, obviously with all necessary tuning.

Kindly let us know how you fare

brgds

Frank

[bluezeeland]

Hi Nigel,

Think that is good idea, have you had the emulsion tubes out ,and the sprocket thingy which is squirting the fuel down the barrels ? This inner liner of fuel lines is a pain in the "bétt", think nowadays fuel is near toxic ?

Anyway, after tinkering about, lets us know how it went

kind regards,

Frank

[nwarner]

Well the not starting when hot reoccurred on Friday when I filled up with petrol after a longish run (to try out the carb. after it's sonic cleaning) and it was also a hot day. After waiting 45 minutes with the bonnet up it started again. When I got back home of course it started fine for a while. Anyway to cut a long story short after some testing, that Adrian suggested earlier, I found that sometimes I was only getting about 5 volts from the wire from the starter solenoid while cranking the engine. I ran a different wire from the solenoid but it was still sometimes 5 volts when the engine was hot. I then ran another earth to the starter motor and again no change so I think it must be a problem in the starter solenoid. As I don't want the hassle of changing the starter motor I have fitted a 12 volt coil and I have done away with the ballast resistor. I should have taken phillpots advice. Hopefully it is now cured.

The misfire also seem to have gone now the carb. has been cleaned. There was quite a bit of muck that came out and it also looks almost new.

Nige

[TVR_owner]

Nigel,
When the time comes to replace the starter, I can recommend the gear driven starters - they don't half spin the engine round

[bluezeeland]

Hi Nigel,

Sounds like the electric and mechanical gremlins have joined forces then ! Spot of bad luck..

Still glad to hear that by investing some in the carb at least the misfiring is cured

The starter is a pain in itself to change, maybe a good idea to 'out-source' ?