Fuel Starvation

Post by **Kevin** » Wed Jul 19, 2006 9:43 pm

Well for those that say they have not had this happen to them coming home from work I called in at a mate for 5 minutes and when I got back in the car the fuel pump went mad for a while and the car was hiccupy to say the least until I got rolling again, then when I got home the car had to be moved a short while after the same thing again, but later on everything is back to normal apart from the pump working overtime for 10 seconds, the common factor being the 33 degrees C

and of course the rise in engine temperature for a while after stopping, so if anyone else tells me its a myth and it never ever happens try a traffic jam or my method above in this heat.

Post by **Judge** » Wed Jul 19, 2006 9:46 pm

Certainly not a myth Kevin, it's happened to me.

Post by **d_harris** » Wed Jul 19, 2006 9:46 pm

well, its never happened to me. I guess though that as things seem to be getting hotter this might be more of a common problem, so there might be a market for heat shields in the future

Post by **bmcecosse** » Wed Jul 19, 2006 10:02 pm

Or just fit the pump much lower down.

Post by **RogerRust** » Thu Jul 20, 2006 7:56 am

I read that on the Australian site where it is hot and sunny every day if the tv is to be believed. They suggest mounting the pump just above tank level on the engine mounting tower and then making a new hose uo to the carb. The only thing that worries me is getting the fuel pipe past the exhaust.

Post by **bmcecosse** » Thu Jul 20, 2006 10:14 am

Mini fuel pipes run right alongside the exhaust and no problems. If there is a blanking plate on trhe block - the easy answer is to fit a cheap mechanical pump and throw the v expensive SU pump away.

Post by **Willie** » Thu Jul 20, 2006 7:38 pm

ROGER.... no problem re the pipe, straighten it out and run it well below the
exhaust level, it will no longer sit above the exhaust soaking up all that heat.
It would need to be fitted so that it could not be damaged by foreign bodies
such as road humps!!

Post by **Kevin** » Thu Jul 20, 2006 8:37 pm

Mini fuel pipes run right alongside the exhaust and no problems.

Sorry but I dont have a Mini so thats not relevant and if I remember correctly as Cam said its a different type of pump and location.

the easy answer is to fit a cheap mechanical pump

Very cheap, I dont think so if there is no blanking plate on the block like most of our engines.

And just because I have not suffered from a particular problem another owner has had does not mean I dont believe them I just regard problems are for expanding my knowledge.

Post by **Cam** » Wed Jul 26, 2006 9:55 pm

Kevin,

Snap! I had the same problem at around 2-3pm sitting in a traffic jam between Macclesfield & Hazel Grove at the wonderful roadworks. By the time I got to my destination the fuel pump was ticking away like mad and Gracie was mis-firing a bit. Once I got back onto a straight road and the speed increased, it was fine.

Yes, the Mini is not a good comparison as the systems are not 'like-for-like'

Post by **bmcecosse** » Thu Jul 27, 2006 1:17 pm

Same engine -same petrol!! But obviously the problem is caused by the high up position of the SU pump - so (as I said already) - IF there is a blanking plate - fit the mechanical pump. They are much less expensive than the SU to replace. If no blanking plate - and you are troubled with the splutters - then lower the pump to reduce the suction height. It can't be nearness to the exhaust because Minis don't have the problem and their pipes are right alongside the exhaust. It is the suction height - which with warm petrol causes bubbles in the fuel undersuction. Remove the suction - problem solved.

Post by **Kevin** » Thu Jul 27, 2006 1:57 pm

Cam

In the queue for Classics on the Common yesterday at around 4pm with a 35 ish temperature 4 out of the 6 of us in convoy were suffering and very grateful to park up and cool down, we also decided to have a quick look, and all of them had very hot fuel pipes to the pump and from pump to carb and the carb itself was even hotter so it looks like the whole area is a natural heat sink.

Post by **chickenjohn** » Thu Jul 27, 2006 2:10 pm

I thought the Mini has a slightly different pump?- it pushes from the tank, wheras the Minor pump sucks to the carb. Pressure will stop flue vapourising in the pipe, wheras suction will encourage it.

Maybe its possible to fit a Mini pump near the tank in addition to the Minor one near the carb??

Just an idea.

Post by **ummers** » Mon Aug 07, 2006 7:04 pm

This is certainly very familiar to me. i have a '68 saloon and on longer journeys (over 20 miles) the same thing starts to happen to a point where it will stall and won't restart until its cooled down a bit. I've heard there is a type of heat shield from a mini you can get that fits around the carb and that people move the fuel line away further from the exhaust also uner the car. Has anyone else heard of this mini heat shield, ie what type and where to get it and does it work?

Post by **d_harris** » Mon Aug 07, 2006 7:31 pm

I did actually have it happen in the convertible the other day!

Post by **bmcecosse** » Mon Aug 07, 2006 10:23 pm

All the Minis since the 70's have used mechanical pump on the block - sucking from the tank. Earlier cars had SU pusher pump in the rear subby - where it soaked up mud and salt until it failed misearbly and most inaccessibly!!
There is no heat shield on the normal Mini - although twin carbs have a sort of heat shield flat plate - discarded by many. Some folks wrap the exhaust manifold in insulation type material to keep heat in the gases. I have done this because my Mini lcb exhaust is right alondside the fuel pump and pipes - never had any splutters - just nervous of red hot exhaust (when in full flight) and petrol about 1" away !!

Ratbag · Post by **Ratbag** » Tue Aug 08, 2006 9:56 am

Kevin wrote:Well for those that say they have not had this happen to them coming home from work I called in at a mate for 5 minutes and when I got back in the car the fuel pump went mad for a while and the car was hiccupy to say the least until I got rolling again, then when I got home the car had to be moved a short while after the same thing again, but later on everything is back to normal apart from the pump working overtime for 10 seconds, the common factor being the 33 degrees C and of course the rise in engine temperature for a while after stopping, so if anyone else tells me its a myth and it never ever happens try a traffic jam or my method above in this heat.

May be worth doing what you can to reduce underbonnet temperatures. Wrap the exhaust manifold & downpipe with insulating tape - as a secondary benefit this will also keep the silencer hotter & help prolong its life.
Looking at the mog engine bay, air enters via the grille/front, goes through the rad - then where does it exit? Hot air rises - and where is the fuel pump? Up high at the back..... A couple of grilles in the trailing edge of the bonnet could work wonders both for fuel vapourisation and engine cooling.

Just some thoughts,

Phil

Post by **ummers** » Tue Aug 08, 2006 10:18 am

Phil

I certainly think you have a point about reducing under bonnet temperatures. Something else I have left from an MG magazine (I also have a B) is that modern fuels are more prone to vaporisation than 4 star etc. which isn't helping the situation.

Also, has anyone tried that Water Wetter product in their rads to try to keep temperatures down? It supposed to lower temperatures by 15 degrees, though i am a bit sceptical.

Dan

Post by **ColinP** » Tue Aug 08, 2006 10:51 am

The most effective solution to this problem is the one Cam uses (IMHO) - a pusher pump at the tank end, plus a regulator jsut before the float chamber.

However, lowering the pump should reduce the problem (modern fuels have a significant vapour pressure at 30C - so that 6 psi "suck" will tend to boil the petrol). Moving the pump 2 feet lower will reduce the amount of suck needed a lot.

Underbonnet cooling might be a good way forward - I've noticed a tendency to vapourisation - but only stationary in traffic - not driving. The dificulty is how to not have odd vents/louvers....

Water Wetter product in their rads to try to keep temperatures down? It supposed to lower temperatures by 15 degrees, though i am a bit sceptical

- me too - the temperature is set by the thermostat and then the cooling ability of the radiator. The coolant properties shouldn't be significant (unless they are extreme!)

Colin

Post by **Kevin** » Tue Aug 08, 2006 12:23 pm

A couple of grilles in the trailing edge of the bonnet could work wonders both for fuel vapourisation and engine

Most of us wouldnt want to start cutting holes in the bonnet though.

modern fuels are more prone to vaporisation than 4 star etc. which isn't helping the situation.

Yes we all agree on that point.
There also used to be a heat shield kit made by Grumpys (no longer trading) but the couple of owners who I know that had them fitted still suffered from the problem.
The main problem is that many owners dont wish to change the underbonnet looks which makes the 3 main mods impractical, these being the pusher pump above as mentioned, the repositioning of the pump lower in the engine bay or if you have the opening in your block to fit a mechanical pump which is also lower down, so its a bit of a no win situation if you want originality.

Post by **alex_holden** » Tue Aug 08, 2006 12:42 pm

Kevin wrote:The main problem is that many owners dont wish to change the underbonnet looks which makes the 3 main mods impractical, these being the pusher pump above as mentioned, the repositioning of the pump lower in the engine bay or if you have the opening in your block to fit a mechanical pump which is also lower down, so its a bit of a no win situation if you want originality.

You could always fit a hidden pusher pump and leave the existing pump in place.

Morris Minor Owners Club

Fuel Starvation

Fuel Starvation

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Re: Fuel Starvation