Fuel vapourisation issue

oport

oport

Member
Hello fellow Rover drivers,

it seems that the fuel vaourisation issues are a hot (sic) topic right now. I assume i have the same problem, because after a while in hot weather driving higher speeds my car starts to stutter and power goes away. The engine does not die, and when i switch the engine off and wait a couple of minutes, the problem goes away for a while. It is directly temperature related, because in cold weather the car runs like hell even at high speeds for a long time.

OK, what to do next? I have replaced all ignition components and fitted an electric fuel pump (Pierburg) in the engine bay. The pump and fuel lines are really close to the left cylinder bank. What can i do to keep it cooler? Put it further up front nearer to the cooler or put it lower in the engine bay? There is not much room to fiddle with. Or would some heat insualtion material do any good there? Any suggestions? Every hint is welcome, because this problem leads to the fact that my wife does not like to take the P6 for longer trips, which is not good.

CU Olaf
 
hi i had the same problem with my v8 wot i done with my fuel line is ran is from the back of the engine then next down the inner wing by the front suspension and throught a hole straight in to the pump since that had no problems at all with mine it great in all weather now and it even still runs fine in traffic now
 
Hello Olaf,

My own view on the fuel vaporisation problem which your car certainly appears to be displaying, is that it is directly related to the fuel. That however does not answer the question as to what needs to be done in order to minimise the effect. From what you have said Olaf, I would start by immediately relocating your fuel pump. Being in the engine bay it is of the type which pulls fuel through rather that those which are located beneath the car near the tank, the "pushers". Ideally the best option would be to remove your current pump and replace it with a a suitable pump that is designed to be placed near the tank. My reasoning is that when the fuel vapourises before the pump in the engine bay, there will be pockets of gas being delivered and this is going to make itself felt by the symptoms that your car is displaying now. Having the pump at the rear removes this possibility all together. Because there is a constant stream of fuel being pushed from behind, vapour pockets if they occur are quickly closed and the stuttering problems don't eventuate.

If you don't wish to go down this path, then remove and relocate the pump the pump further away from the manifold and lower down if possible. Fibreglass matting is a good product to use to unsulate your fuel lines with.

Ron.
 
Have you checked how clean the cooling system is? When was the last time your radiator was recored? is the thermostat opening and closing at the correct temperature? You gauge is an indicator but you may be running on the hot side.

I am a great believer in having a healthy cooling system as it seems to make certain problems disappear.
 
Hello arthuy,

yes, the cooling system seems to be fine. Temperature gauge barely moves over the first quarter of green, no hot starting problems whatsoever. I am really focusing on the fuel vapourization now. My first try will be to keep the Pierburg sucker pump up front and reroute the fuel lines further away from the block and the exhaust, probably adding some heat insulation material.

If that does not help, then I will probably go down testriders route and put the fuel pump back at the tank.

CU Olaf
 
well do wot i do to mine i got my electric fuel pump behind the head light bowl ran some copper pip from the tap behind the engine down the inner wing next to the suspension then through a hole straight to the pump did my months ago and it great now and great in traffic get no fuel vaourisation at all i will try and upload a photo to show you
gareth
 
Hi Gareth,

your solution sounds good. Thanks for your advice, it would be very nice if you can upload a picture to give me a rough idea how you solved it.

CU Olaf
 
As I said the gauge is only an indication and should be treated as such. I have an infra red thermometer which you can point at any surface and get a reading of the exact temperature.

I know you are not looking at the cooling system but don't rule it out. As a quick and easy check I would remove the theromstat and see if you still get vaporisation (I think it will disappear). With regards to the thermostat do you know which one you have fitted? there are various ones depending on the temperature you want it to open at, it is easy to fit the wrong one. You wont overheat but will run hotter than the car likes.

I have seen people over the years fitting electric pumps and fans and eventual get the radiator recored. I am all for finding the route cause of problems.

Colin
 
Olaf,..next time the car suffers the same systems, pull over, switch off and undo the top nut on the fuel filter, assuming that you still have this arrangement. If it hisses and spits then you will know immediately it is fuel related.

Ron.
 
arthuy said:
As I said the gauge is only an indication and should be treated as such. I have an infra red thermometer which you can point at any surface and get a reading of the exact temperature.

I know you are not looking at the cooling system but don't rule it out. As a quick and easy check I would remove the theromstat and see if you still get vaporisation (I think it will disappear). With regards to the thermostat do you know which one you have fitted? there are various ones depending on the temperature you want it to open at, it is easy to fit the wrong one. You wont overheat but will run hotter than the car likes.

I have seen people over the years fitting electric pumps and fans and eventual get the radiator recored. I am all for finding the route cause of problems.

Colin
Click to expand...
I can only echo this. I've worked on hundreds over the years and owned many as daily drivers and never needed all the conversions. The fan option is good for saving fuel, quicker warm up and less noise though :)
When in good order they were always fine when current :wink:
 
hi CU Olaf here is the pics to show you how i have done mine
this is from the fuel tap from the back of the engine
19075857a12462848466l.jpg

then curved round to the inner wing then behind the shock
19075857a12462848474l.jpg

then thorugh the brake pipe to the front
19075857a12462848486l.jpg

then straight to the pump
19075857a12462848497l.jpg

the the outlet pipe to the filter then to the carbs this has been done months ago and works very well hope this helps you out
gareth
 
GrimV8 said:
arthuy said:
As I said the gauge is only an indication and should be treated as such. I have an infra red thermometer which you can point at any surface and get a reading of the exact temperature.

I know you are not looking at the cooling system but don't rule it out. As a quick and easy check I would remove the theromstat and see if you still get vaporisation (I think it will disappear). With regards to the thermostat do you know which one you have fitted? there are various ones depending on the temperature you want it to open at, it is easy to fit the wrong one. You wont overheat but will run hotter than the car likes.

I have seen people over the years fitting electric pumps and fans and eventual get the radiator recored. I am all for finding the route cause of problems.

Colin
Click to expand...
I can only echo this. I've worked on hundreds over the years and owned many as daily drivers and never needed all the conversions. The fan option is good for saving fuel, quicker warm up and less noise though :)
When in good order they were always fine when current :wink:
Click to expand...

Add my name to this list too. I've never had to resort to fitting an electric pump to cure vapourisation, and I cured plenty that were suffering with the problem. The only difference between then and now is the loss of decent fuel caused by the intro of unleaded, and I can't see why any adverse effects caused by that couldn't be cured by using an octane booster. Fitting electric pumps just cures the symptom, not the underlying cause.
 
I'm a bit nervous of that assesment Harvey. I'd like to agree, but the sheer number of people who have suffered like this and subsequently solved the problem with an electric pump makes me think the problem is a little deeper than just getting everything as the factory intended.

First off there are a few things I think are important in terms of the general condition of the car. I think there have been a number of people who have identified blockages in the water jacket of the inlet manifold when rebuilding engines. Especially restricted flow from the small pipe at the front. This is clearly going to raise the temperature close to the carbs. Then any less than optimum performance of the water pump, fuel pump, carb float chambers are obviously going to contribute. And of course it is very possible to have pinhole leaks in the fuel lines that draw air without showing as leaks.

Then lets look what Rover did when it knew a car was going to operate in very hot conditions. The NADA's had a rear electric pump, but more importantly addressed underbonnet temperatures by means of the outer two scoops being opened to let hot air out when standing. This latter feature was Rover's second attempt at the same fix, numbers of prototypes including the P7's had rear facing pressed in grilles/louvres up the outer edges of the bonnet. This is famously criticised as allowing engine bay fumes into the heater intake, which is probably why the NADA outer vents were developed. A number of racers also run with the rear edge of the bonnet raised to achieve the same result.

So why do cars have such different experience of this problem? One reason could be the standard of fit of the bonnet and the condition of the front and rear rubber seals. The front rubber seal in trouble will degrade the cooling capacity of the readiator by allowing air to bypass the rad. If the rear is a particularely good fit then hot air is more likely to be trapped. Standards of bonnet fit vary widely. Mine had a shot hinge on one side which allowed the rear of the bonnet to flutter. That would have helped with engine bay temperature. It's also evident that a lot of bonnets don't sit down onto the side buffers, these will have a further heat outlet denied to well adjusted bonnets.

My conclusion is that the installation is marginal and probably doesn't need much to be less than ideal to give problems.

What would be my recipe for success?

1 Fit three row radiator core.

2 Strip and clean out the inlet manifold.

3 Renew the rubber seal on the front edge of the bonnet.

4 Fit a NADA style pusher pump.

5 Raise the rear edge of the bonnet very slightly by washering under the hinges.


Gareth - your installation is very neat and intelligent - gets the petrol line well away from the heat problem!

Chris
 
I can only speak from the UK perspective, and that is I've never had to resort to an electric pump. Other countries with hotter climates are not something I have any experience of. V8 cooling systems are marginal at the best of times, particularly rads, and if they're not shifting the heat it will just build up and escape elsewhere, and during that process it will vapourise the fuel. Fitting an electric pump is curing the symptom of excess heat. If the cooling system is in good order, along with the mechanical pump then I still say that you shouldn't need an electric pump. That's not to say you can't fit one if you want to, just that you shouldn't need to. There have been postings in this and the other similar thread that to me give absolutely spot on descriptions of vapourisation and the conditions under which it occurs, and others where I very much doubt that was what was happening.
 
hi chris yea its a great idea as i was having all the same problems and when i wanted to put a electric pump on at the front so i thought i would move the pipe away from the engine and since this has been done its great and to be honest the nada bonnet make a hell of a difference when i took it to malvern it was great cool all the way down then and when it was just ticking over it dont get to hot any more
 
Gareth,
If I may be so bold as to suggest a slight change to your installation, please?

In the top picture on the right side there is a ty-wrap/zip tie holding the pipe in place that I highly recommend you remove and replace with a p-clip or similar rigid fastener. Zip ties are great, but it WILL wear through that pipe and in reasonably short order too if left like that. Being a fuel pipe, I imagine that you would prefer it intact.

Great idea otherwise and one that is going on my list of to do's for when I eventually get started on my old girl.
 
You must log in or register to reply here.
Back
Top