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I'm stuck. Pos vapour lock?


ShaunW
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Guys. Been out for a short drive (10mls) left car for 30min now it won't start. It'll catch but only run for a few secs. Did run for about 30s and I got 50yds and it durd. Elecs seem fine. Is the answers to leave it an hour or call the AA :angry: It's always started fine. It's a 2500 non pi. 

Help! 

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Shaun,

Sometimes the tank vent gets blocked and there's a build up of pressure in the tank, eventually defeating the pump. When it happens open the fuel cap, is there a woosh of air? I also suffered from sludge in the fuel lines, I dyno rodded them out with strimmer cord. A friend ran out off fuel and filled up from a small tank, unknown to him a heavy washer came off the spout and would periodically get sucked over the fuel tank outlet blocking the line. Took weeks to find the cause.

Doug

 

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Cheers Doug. Interesting idea to use strimmer cord. I'm as convinced as I can be that I'm getting fuel and the tank is vented well. Temps seem to have been the problem. After an hour parked in the shade it was like there'd never been a problem. 

Does make me wonder why it doesn't happen more often, the engine temp wasn't especially high, maybe 90ish according to the dial I use to set my electric fan cut in temp, and with the exhaust manifold so close to the inlet manifold which is also heated. 

This issue is new to me. When it's running it seems good so I don't think it's something like the choke being stuck on or an especially rich mixture. 

I searched the forum for vapour lock and also hot start and didn’t find anything which I thought was strange. If anyone can point me at some further reading either here or elsewhere that would be great. I don't want to worry every time the sun comes out because that's the only time I use her. 

I was amazed at how quickly I got a reply. This place really is the 5th(?) emergency service. :) 

 

 

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The logic behind Danny's suggestion is that, when you let the car sit for a half hour after a run, the residual heat soaks out into places that would normally be cooled by flow of air or fuel. If the pump gets hot enough to vaporise the fuel inside, it doesn't actually pump very well. I certainly had my VItesse get into a "can't run, won't run" state on a hot day, which was instantly cured, at least for a while, by pouring a cup of cold water over the fuel pump.

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Thanks NM, I've got an electronic fuel pump so I'm safe on that count. 

Good point Yorkshire, condenser was new when I got the car (12mths ago) but the coil does look a bit tired. 

Doug, I only mentioned vapour lock because I'd heard of it. It's a case of a little knowledge being a misleading thing I suspect. 

So, time for a fresh coil I think...any recommendations? Just regular driving around locally most of the time, I don't mind going better than budget but probably not worth spending silly money on a super dooper one. 

 

 

20170830_180131-1-1.jpg

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Avoid lucas branded and intermotor coils....best out there are probably the bosch ones? 12v one below for non-ballasted ignition

https://www.carparts4less.co.uk/search/413110037?gclid=Cj0KCQjwmPPYBRCgARIsALOziAOYnoDRXvz0PsEiOSlrny5zdL1a_ngaN5oxjrayLHvWg4HY7vVFivEaAvINEALw_wcB

I had trouble with new condensers being poor, and fitted electronic ignition. In 20 plus years over 5 cars no issues (longest was 12 years as an everyday car, but my herald estate was about 10 years, our mini 5 and the current toledo has a cheap stealth one, 3 years and all faultless) 

Re cooling, does the fan stay on with the ignition off? that will help. And are the carbs heat shielded? Again pretty essential. Failing that, there may be a reason GT6 owners have a propensity for leaving their bonnets up...

 

 

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38 minutes ago, clive said:

 Failing that, there may be a reason GT6 owners have a propensity for leaving their bonnets up...

Oddly, my GT6 has never shown the slightest hint of any overheating problem. Even stuck in North Circular traffic after the hottest RBRR on record, with the gauge climbing rapidly past 3/4, it was merely "hot" and not even mildly "bothered". Unlike the occupants.

Edit: Actually there was the start of the Shakespeare's Summer Scatter, when the 50-year-old hose from the manifold to the return pipe decided to fail just as we parked up, but cutting off the split end and re-connecting made it good for another few thousand miles.

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 Rob,

Get yourself a polyurethane tunnel lined with heat/sound deadening, same stuff on the bulkhead, then discover your heater hasn't been working for several decades. :lol:

Clive,

Lucus is no longer Lucus unless it's old stock. (But you knew that! :lol:)  My Aldon, about the most expensive EI you can buy, recently failed, 3 years old. Always carry points, capacitor and fixing bits in a plastic bag in the glove compartment. Otherwise you have to summon a son-in-law to help you collect the bag from the garage. :angry:

Doug

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Doug, I had a look at Lucas's history. Seems a few years ago the owners basically put making the stuff out to tender...... Sounds perfect for making sure you are producing quality stuff:angry: but means low overheads and risk:), at least for the company owners.

Prior to the stealth unit in my toledo, all had been pertronix (aldon are pertronix with a new label stuck over the pertronix one) and as far as I know, still OK. I do worry about the toledo unit. Points wouldn't help much, as all he gubbins are under the advance weights/springs. Dreadful design. Still, fitting new advance springs was easy.

Rob, since that RBRR I reckon fuel has changed.... I think the early cars with the louvres helped when a car was left. Maybe a fan that whirrs away for 20 mins after shutoff is the answer....

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I got sick of the poor quality replacement point and condensor units and just put the cheap "SimonBBC" Powerspark unit in. It might not be map-able etc. but it's done good service on 1xRBRR and 2x10CR over a 4 year (about 14K miles)  period without any issues. Yes, I still carry a "known good" points unit, screwdriver and feeler gauges in the boot, so far (touch wood) I've never needed them.

 

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1 hour ago, clive said:

Rob, since that RBRR I reckon fuel has changed.... I think the early cars with the louvres helped when a car was left. Maybe a fan that whirrs away for 20 mins after shutoff is the answer....

Yes, fuel has definitely changed, which I suspect is why it gave 36MPG on that one and never better than 28 in the last ten years. This doesn't seem to have affected its heat tolerance much, beyond an annoying tendency to low speed misfires when pulling away gently in traffic, although that seems more related to modern NGK plugs.

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5 hours ago, clive said:

Avoid lucas branded and intermotor coils....best out there are probably the bosch ones? 12v one below for non-ballasted ignition

https://www.carparts4less.co.uk/search/413110037?gclid=Cj0KCQjwmPPYBRCgARIsALOziAOYnoDRXvz0PsEiOSlrny5zdL1a_ngaN5oxjrayLHvWg4HY7vVFivEaAvINEALw_wcB

Re cooling, does the fan stay on with the ignition off? that will help. And are the carbs heat shielded? Again pretty essential. Failing that, there may be a reason GT6 owners have a propensity for leaving their bonnets up...

Yes my fan stays on without the ignition. I've got it set at about 85.

I'm interested that you say I need a non ballasted coil. I thought I'd read elsewhere that having the extra pale pink wire to the - ve meant it was ballasted? That said my engine is a CP and the listings I saw for coils seemed to say that pre CR1 is non ballasted and post CR1 is ballasted.  I'm guessing it's not the engine that's the issue, more than the ignition system that was installed when certain engines were being installed?? I'll go measure the resistance across it and report back. 

Carbs aren't heat shielded. Is there a part number I should be looking at? 

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