pauljh Posted September 12, 2020 Report Share Posted September 12, 2020 (edited) Hi folks I’m new to this forum and I’m hoping someone can help me with an issue I have with my 6. I have basic mechanic abilities, Ie. engine service, brakes etc but I’m learning. I have a 71 PI. Car starts from cold, ticks over nicely then begins to stall when reaches temperature and cuts out completely when hot. I’ve replaced plugs, points, condenser, rotor, coil & fuel filter. Problem persists, runs well until it gets hot then starts stalling before cutting out completely. Choke seems to be functioning normally. When it’s running I can feel fuel pumping to the MU and to the injectors. I’m assuming it must be either fuel or spark and I seem to have both. I’m wondering if it’s something to do with the metering unit or Bosch pump. Any thoughts on this would be gratefully received. ...just thought. It might not be due to heat as it was idling normally and when it got to normal temperature I gave it a small amount of throttle and it starting stalling. So maybe a fuel delivery issue? Edited September 12, 2020 by pauljh Quote Link to post Share on other sites
jimcwestie Posted September 12, 2020 Report Share Posted September 12, 2020 Check and see if the metering unit choke lever is fully returning. Jim Quote Link to post Share on other sites
pauljh Posted September 12, 2020 Author Report Share Posted September 12, 2020 Thanks Jim, I did check that and the lever appears to be in the fully returned position. Quote Link to post Share on other sites
John L Posted September 12, 2020 Report Share Posted September 12, 2020 If you have an idle air valve at the front of the number 1 inlet manifold you may have to open it to increase the amount of air at idle speed, let us know if you have this and did it allow idle speed to increase. If that doesn't work you will have to adjust all the throttle rods and balance the inlets to open the butterflies all the same amount. john Quote Link to post Share on other sites
PodOne Posted September 12, 2020 Report Share Posted September 12, 2020 Was the engine running fine prior to this fault or has it appeared to have gradually developed? and have you changed anything prior. While warming up can you rev her without stalling? From the sounds of it it might be that as the fuel pump warms up it can't deliver enough fuel so check the pump has 12-13v or better and clean the earth to the pump. What's the fuel pressure at the metering unit should be around 105 psi if I remember correctly. I'd be tempted not to adjust anything before checking or you might add other variables to your issue. Andy Quote Link to post Share on other sites
pauljh Posted September 12, 2020 Author Report Share Posted September 12, 2020 Andy, thanks for this. Engine was running fine prior to fault so developed suddenly. First time it happened I had black smoke from the exhaust but since changing electrics this hasn’t happened again. Only job I did on the same day it first happened was remove gear stick to fix rattle in 3rd, it was when I went to test drive It that this fault occurred, didn’t think it could be related. I can rev whilst its warming then splutters and dies as soon as it reaches temperature. The possible issue with fuel pump makes sense and I will do the checks you suggest. I don’t know PSI at MU but I’ll attempt that check too. Thanks again for the suggestions. Quote Link to post Share on other sites
pauljh Posted September 12, 2020 Author Report Share Posted September 12, 2020 John thanks for your suggestions, I’ll check the fuel pump is working at temperature first before I move to the idle air valve. Beyond that I’m probably moving out of my comfort zone!! Quote Link to post Share on other sites
Mike C Posted September 12, 2020 Report Share Posted September 12, 2020 Pull a plug and check that you get a fat , blue spark with a hot engine. Might sort out if it's an ignition problem. Quote Link to post Share on other sites
Waldi Posted September 13, 2020 Report Share Posted September 13, 2020 I would check the plugs as suggested above wgen hot, after stalling, see if the give an acceptable spark, on all 6 of em. If they do not spark, replace by new ones. If ok, likely a fuel issue. Did you fit a new red rotor or a black one with a rivet? The last one is known to fail. Waldi Quote Link to post Share on other sites
pauljh Posted September 13, 2020 Author Report Share Posted September 13, 2020 Thanks for all your replies on this. I’ve checked fuel pump, is getting 12v, cleaned connectors and seems to be working OK. Tried to fire it up this morning, wanted to to start then nothing. Checked the plugs, soaking wet. Ignition parts have all been replaced, plugs, points, coil, cap, condenser, red rotor arm. HT leads new last year. Was on the button when I replaced these parts yesterday and idled nicely until it got hot and I flicked the throttle. Not sure why it won’t start now but I think I’m moving beyond my skill set! Quote Link to post Share on other sites
pauljh Posted September 13, 2020 Author Report Share Posted September 13, 2020 ...removed a plug and getting a good spark although engine is cold as it won’t start. Quote Link to post Share on other sites
John McCormack Posted September 13, 2020 Report Share Posted September 13, 2020 18 hours ago, pauljh said: Thanks Jim, I did check that and the lever appears to be in the fully returned position. Hi, the lever can return to the off position and the enrichment cam can still be in the rich position. Put a finger down between the block and the MU and you will feel a nut on the enrichment mechanism. Push it very very hard towards the back of the car. It will click back a bit if it is still on. This is a common problem, especially with cars that haven't been used regularly. It happened to mine, exactly, and I mean exactly, your symptoms. I sprayed WD40 liberally down there and worked the mechanism backwards and forwards for 10 minutes. Problem solved. Quote Link to post Share on other sites
pauljh Posted September 13, 2020 Author Report Share Posted September 13, 2020 Thanks for the tip, checked this again. The choke lever is fully returned. From what I can see this lever pushes a 2nd lever with a small adjustable nut and bolt. This second lever was as far as it would go towards the back of the car and firmly against the bottom of the choke lever. WD40’d everything but it didn’t appear stuck on. Cleaned the plugs, cranked it, almost fired up, checked the plugs, wet with fuel. Quote Link to post Share on other sites
John L Posted September 13, 2020 Report Share Posted September 13, 2020 These are really good testers for knowing if you have a good spark or not, without dismantling too much, https://simonbbc.com/sparkrite-spark-plug-tester-set-of-6/ Quote Link to post Share on other sites
BlueTR3A-5EKT Posted September 13, 2020 Report Share Posted September 13, 2020 (edited) Is the coil wired correctly negative terminal connected by wire to the distributor if you have points and negative earth as original Edited September 13, 2020 by BlueTR3A-5EKT Quote Link to post Share on other sites
pauljh Posted September 13, 2020 Author Report Share Posted September 13, 2020 Coil is wired correctly and as you describe. The same as when it was running normally. Quote Link to post Share on other sites
pauljh Posted September 14, 2020 Author Report Share Posted September 14, 2020 Hi I’m now thinking this might be an alternator issue. Car started today after allowing excess fuel to evaporate. Idled for a while then began to stall, finally stalling completely. I noticed that the AMP gauge needle was to the far left C+ when it was running, I don’t think this is normal. The battery was showing 12.7v when it was running, should this not be higher if the alternator is working properly? Apologies for the basic explanations but I’m still learning (the hard way). Quote Link to post Share on other sites
PodOne Posted September 14, 2020 Report Share Posted September 14, 2020 A healthy alternator should normally be giving around 14-14.3v at the battery. Have you tried a fresh fully charged battery from another car with the alternator un plugged and see if she will start, warm and idle for you for longer? Or just whip the alternator off and have a auto electrical reconditioner test it. Quote Link to post Share on other sites
pauljh Posted September 14, 2020 Author Report Share Posted September 14, 2020 Thanks for that, I thought so re the voltage at the battery. Maybe I’ll start it up tomorrow and if I can gets some revs up before she stalls I’ll check If the charge at the battery falls. Quote Link to post Share on other sites
Mike C Posted September 14, 2020 Report Share Posted September 14, 2020 The alternator not charging could be a connection in the charging system that's opening up when it gets warm- but if you have over 12 V at the battery the engine should still run. Quote Link to post Share on other sites
Robert Wilsher Posted September 15, 2020 Report Share Posted September 15, 2020 I’ve had similar problems...finally discovered that the fuel pump is providing 100 psi until the engine warms up then drops to 40 psi and understandably the engine dies... after a while 100psi again then same pattern... you can rent a pressure gauge for about £20 or buy one for £75 cheers Rob Quote Link to post Share on other sites
pauljh Posted April 30, 2021 Author Report Share Posted April 30, 2021 Hi all, apologies for the very late reply on this topic but thanks everyone who replied with their thoughts, it was very helpful. Problem was a faulty MU which I replaced with a refurbed unit and installed elec ignition whilst I was at it and now running sweet again. Latest job is a gearbox rebuild, I’m looking forward to actually driving it at some point!! Quote Link to post Share on other sites
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