Hot Start problems...
Discussion
Arghhh!!
My 450SE is a B*st*rd to start when it's up to temperature/hot! I read about this when I had a Griff, but mine didn't really suffer??
There's some fix-kit for it, but I seem to remember fuel evaporation being the cause?
Any help would be gratefully accepted...
My 450SE is a B*st*rd to start when it's up to temperature/hot! I read about this when I had a Griff, but mine didn't really suffer??
There's some fix-kit for it, but I seem to remember fuel evaporation being the cause?
Any help would be gratefully accepted...
- EDIT*
Edited by hillclimbmanic on Thursday 3rd October 18:12
There was a starter motor available with a reduction drive which were known to give a faster cranking speed, maybe you have one of those.
Could be your fuel pressure regulator isn't keeping the rail at pressure for very long. If you can rig up a way to over-ride the fuel pump relay you could prime it manually when hot and see if that fixes it, might at least point you in a direction.
Could be your fuel pressure regulator isn't keeping the rail at pressure for very long. If you can rig up a way to over-ride the fuel pump relay you could prime it manually when hot and see if that fixes it, might at least point you in a direction.
Wedg1e said:
There was a starter motor available with a reduction drive which were known to give a faster cranking speed, maybe you have one of those.
Could be your fuel pressure regulator isn't keeping the rail at pressure for very long. If you can rig up a way to over-ride the fuel pump relay you could prime it manually when hot and see if that fixes it, might at least point you in a direction.
Thanks for the reply, Ian! It's as good a place to start as any...I'll give it a try. what's your take on the fuel pipe getting hot, causing the fuel to evaporate?Could be your fuel pressure regulator isn't keeping the rail at pressure for very long. If you can rig up a way to over-ride the fuel pump relay you could prime it manually when hot and see if that fixes it, might at least point you in a direction.
Edited by hillclimbmanic on Friday 4th October 08:33
I had a similar issue with my old SEAC when in the garage filling up with fuel. I thought it was fuel vapourisation so fitted heat wrap to the exhausts - no difference. It slowly got worse until it wouldn't spin over properly yet it was fine when cold.
It turned out the earth lead from the battery to the engine was corroded internally so nice and shiny on the outside, rusty coloured on the inside when you flexed it. Replaced that and never had an issue again hot or cold.
It turned out the earth lead from the battery to the engine was corroded internally so nice and shiny on the outside, rusty coloured on the inside when you flexed it. Replaced that and never had an issue again hot or cold.
Fuel vapourisation is not a "thing" with injection. We are running with 30? psi so 2 atmospheres, so the boiling point is pretty high.
More likely it's ECU-related, so start with the coolant temp sensor (maybe it's wrong when hot) and re-check that at the ECU multiplug too.
Disconnect the cold start injector (top of plenum).
Battery - charged OK? Turning over fine?
When it does start, is it sooty or OK?
Those are the easy things, now over to more tricky - could be the ECU itself, so get the solder "re-flowed", it doesn't take long with a decent soldering iron.
More likely it's ECU-related, so start with the coolant temp sensor (maybe it's wrong when hot) and re-check that at the ECU multiplug too.
Disconnect the cold start injector (top of plenum).
Battery - charged OK? Turning over fine?
When it does start, is it sooty or OK?
Those are the easy things, now over to more tricky - could be the ECU itself, so get the solder "re-flowed", it doesn't take long with a decent soldering iron.
adam quantrill said:
Fuel vapourisation is not a "thing" with injection. We are running with 30? psi so 2 atmospheres, so the boiling point is pretty high.
More likely it's ECU-related, so start with the coolant temp sensor (maybe it's wrong when hot) and re-check that at the ECU multiplug too.
Disconnect the cold start injector (top of plenum).
Battery - charged OK? Turning over fine?
When it does start, is it sooty or OK?
Those are the easy things, now over to more tricky - could be the ECU itself, so get the solder "re-flowed", it doesn't take long with a decent soldering iron.
Somebody said today that fuel injection shouldn't suffer from evap...The battery is spinning the starter motor like a mutha, so I need to check some of the things that you mention, Adam...Cheers!More likely it's ECU-related, so start with the coolant temp sensor (maybe it's wrong when hot) and re-check that at the ECU multiplug too.
Disconnect the cold start injector (top of plenum).
Battery - charged OK? Turning over fine?
When it does start, is it sooty or OK?
Those are the easy things, now over to more tricky - could be the ECU itself, so get the solder "re-flowed", it doesn't take long with a decent soldering iron.
Manic
In theory, the fuel cant evaporate TO anywhere, but that's not to say it isn't becoming vapour. If it did, though, would the rail pressure rise, lifting the pressure regulator and allowing the vapour to blow back to the tank? And if so, when the pump restarts, does the incoming fuel encounter a rail full of vapour, slowing down its ability to refill the rail?
I wouldn't expect the exhaust heat to be a direct cause, there's enough heat rising from the Vee under the fuel rail to warm things up!
I'm not sure of the actual mechanism at work, just tossing ideas around... but I would think that being able to run the pump manually for a few seconds might 'blow through' the lines leading to less cranking.
My car has a modified Lucas dash switch that allows me to prime the rail, it definitely speeds things up when the car has been sat unused for a while, though I can't say hot starting has ever been an issue with it. I say modified because it's an electric window switch, adapted to be latching one way and spring-return the other. The sprung side runs the fuel pump and the latched side switches the over-run vacuum switch in or out (so I get pops and bangs only when I want them, which is handy when coming home late).
Another possibility might be the ignition amplifier if it's mounted on the side of the distributor; as well as needing good contact through the mounting screws to get a solid earth return the amp also uses the distributor as a heatsink. Remove the amp, polish up the back of it and the mounting face on the distributor, use a smear of heat transfer compound and make sure the screws are clean when you refit.
I wouldn't expect the exhaust heat to be a direct cause, there's enough heat rising from the Vee under the fuel rail to warm things up!
I'm not sure of the actual mechanism at work, just tossing ideas around... but I would think that being able to run the pump manually for a few seconds might 'blow through' the lines leading to less cranking.
My car has a modified Lucas dash switch that allows me to prime the rail, it definitely speeds things up when the car has been sat unused for a while, though I can't say hot starting has ever been an issue with it. I say modified because it's an electric window switch, adapted to be latching one way and spring-return the other. The sprung side runs the fuel pump and the latched side switches the over-run vacuum switch in or out (so I get pops and bangs only when I want them, which is handy when coming home late).
Another possibility might be the ignition amplifier if it's mounted on the side of the distributor; as well as needing good contact through the mounting screws to get a solid earth return the amp also uses the distributor as a heatsink. Remove the amp, polish up the back of it and the mounting face on the distributor, use a smear of heat transfer compound and make sure the screws are clean when you refit.
Does it fire if you spray 'easy start' into the plenum?
I had spark and fuel on one of the [V6] Ss and it wouldn't hot start during a Euro Tour. Had fuel and spark but (as I found later) there was an air leak in the plenum when hot. The 'easy start' (well brake cleaner actually) was enough to richen it up enough to fire and run.
I had spark and fuel on one of the [V6] Ss and it wouldn't hot start during a Euro Tour. Had fuel and spark but (as I found later) there was an air leak in the plenum when hot. The 'easy start' (well brake cleaner actually) was enough to richen it up enough to fire and run.
Wedg1e said:
In theory, the fuel cant evaporate TO anywhere, but that's not to say it isn't becoming vapour. If it did, though, would the rail pressure rise, lifting the pressure regulator and allowing the vapour to blow back to the tank? And if so, when the pump restarts, does the incoming fuel encounter a rail full of vapour, slowing down its ability to refill the rail?
.
Nice theory, yes that is something I never thought of, when the pump isn't running, could the vapour "empty" it, so it runs dry? It only has a small head (maybe as low as 20cm of petrol from the tank above?) filling it. I've never known this personally. A clear in-line gauze (NOT paper) pre-filter would be a great way of telling..
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