Overheating fuel pump?

[Dave K]

Well, I had my first hiccup with the new TR6 the other day...

 

I was out and about in Cheshire on Saturday. Absolutely baking hot day. Did about 150 miles and all was well till I dropped off the motorway back near my place. Engine died completely, and I soon realised that the fuel pump didn't sound normal. Instead of the usual whine it sounded like a strangled cat.

 

Anyway, I remembered something from a TR6 book about problems with hot days and overheating fuel pumps, so I opened the boot and waited. After about 10 mins she started, the pump still sounded a bit rough but she ran enough to get home. Started her after a hour in the garage and the pump sounded perfectly normal again.... When I told a TR5 owning friend of mine, he described it as a "classic slip road TR6 incident" and explained the problem.

 

So the question is, is there a fix that could stop this happening again? or is it a case of "they all do that Sir" I already have a Bosch conversion fitted by the way....

 

Any ideas??

 

 

Cheers Dave

Edited May 28, 2010 by Dave K

[radiocheck]

Hi Dave

I wouldn't claim to have the answer here - but I too had a "strangled cat" in the boot of my car the other day as I coasted to a halt.

The car has been returned to the road this spring after a few years in storage and although the petrol tank had been removed and thoroughly cleaned while the car was being recommisioned, the suggestion is some amount of sludge/rust was still present and found it's way into the pipe between the tank and the fuel filter. The noise would indicate fuel not getting to the pump. A new filter seemed to sort the problem.

(It now has another snag but that's another story...)

Best of luck

[ianhoward]

Dave

 

I too have suffered from your 'strangled cat' symptoms - I got home from sea and there was a meeting on that I wanted to go to around 70 miles from home - my wife had all ready gone so I was to meet there there. Anyway, the car had around third of a tank of fuel in so as soon as back home I was into the car - baking hot day last June in high 20's (remember the day it was summer?) No problems at all until near the venue when the traffic severly built up. After around 40 mins the problems started and the engine coughed, spluttered and stopped. Fortunately I realised that it was the 'classic' fuel vapourisation as the fuel in the tank warmed up - by this time there was probably less than 1/4 tank and so little 'heat sink' effect for the returning hot fuel from the engine bay. Anyway, after leaving the car in the shade for 20 mins (and hence cooled down a bit) it started no problem. I then switched off each and every time the traffice was at a halt for even a short while. No problems after that.

 

So whenever possible and if slow traffic is anticipate in hot weather, try to maintain as full a tank as possible!

 

Bosch pump fitted before this occurance...

 

Brgds

Edited May 26, 2010 by ianhoward

[Ragtag]

 

 

So the question is, is there a fix that could stop this happening again? or is it a case of "they all do that Sir" I already have a Bosch conversion fitted by the way....

 

 

 

The problems you describe, relate to the old Lucas pump. My understanding is that the Bosch conversion is supposed to solve all that.

[Alec Pringle]

"My understanding is that the Bosch conversion is supposed to solve all that."

 

Ah, well yes . . . . good stuff, theory.

 

If I was designing a Bosch conversion for a TR injection system, I'd first look at how those Bosch pumps were installed in the applications for which they were originally designed. Mind you, the same thing could be said for the Lucas pump, bearing in mind its wiper motor origin. Either pump can work perfectly well, if it's installed appropriately. Unfortunately, it's usually not. Plus ça change, plus c'est la même chose.

 

Cheers,

 

Alec

[88V8]

My Bosch conversion, installed by Mr Talk For Wales, was sounding a bit busy in the heat at Prescott on Sunday. Dark coloured car, no insulation nor reflective over the tank, tank about 1/3 full. Filter is clean, I cleaned it over winter.

Was surprised I must say as we've been through greater heat with less fuel, wonder if it's due to this bio-muck they're now putting in petrol, even in V-Power.

 

Ivor

[Mike Collins]

My Bosch gets a bit noisy from time to time, does not seem temperature or fuel level dependent though.

 

I found a spoonful of two stroke oil quietens it.

 

Mike.

[John390]

All these cars pump fuel at high pressure. Not all the fuel is used and is returned to the tank. If you have low fuel the returned fuel is hot and eventually all the fuel in the tank gets hot. The fuel then vapourises and causes air locks and the car stalls. The only answer on a hot day is to keep the tank as full as possible. I think most of us have had this happen with Bosch pumps as well!

 

Cheers John

[stuart]

I have found that the cooling coil(original option for Lucas pumps) works very well at cooling fuel so maybe worth adapting the idea to a Bosch setup if you feel the need to go down that route.

Stuart.

[Dave K]

My problem occured with just under 1/2 tank of fuel left, and after a full day out in the sun and a fairly spirited run of about 25 miles on the motorway.

 

Had a look today, here's a photo of the set up on my car...

 

Looking through the suggestions:-

 

Alex, any hints on how the pump should be installed for it to work correctly....

 

Full tank on a hot day, yes I can see that would help. What about driving style, in other words would taking it easy have helped??

 

Clean the filter, yes, can't do any harm...

 

Stuart, The cooling coil, I was wondering about that, or some other way of cooling the pump/fuel supply. The W Kimberley TR6 book talks about sorting it by re-routing a fuel pipe, lagging same, or providing a cooling coil.

 

For now the easy one to do is to keep the tank full, but it'd be nice to find a more permanent fix. Just a thought, would an alternative pump be the answer?? If one exists that is.

 

Cheers all and thanks for the replies

 

Dave

Edited February 10, 2012 by Dave K

[BobE]

Hi Dave

 

Have a look at the replies to pfenlon on the 250/5 forum. Your pump may be fitted to high on the wheel arch. The Bosch pump pushes rather than sucks so it should be fitted below the fuel tank. One solution is to fit the pump outside of the car boot,(as in Peter's photo)much cooler.

 

Cheers

Bob

[Dave K]

Hi Dave

 

Have a look at the replies to pfenlon on the 250/5 forum. Your pump may be fitted to high on the wheel arch. The Bosch pump pushes rather than sucks so it should be fitted below the fuel tank. One solution is to fit the pump outside of the car boot,(as in Peter's photo)much cooler.

 

Cheers

Bob

 

 

Thanks, yes I was looking at that picture. I wonder if that could be part of the problem.....

[Nick Jones]

All these problems have more to do with the fuel temperature than the pump temperature (except where high pump temperature is directly heating the fuel) and the suction lines and pump position also have an effect.

 

What is happening is cavitation, which, crudely, is the fuel boiling in the pump. Two factors cause boiling: temperature and pressure. (Water will boil at 10ºC if the pressure is low enough.) This is why a system that works in cool weather or early in a journey can still be problematic if high ambient temperatures and/or a long run increase the fuel temperature. It is also why it matters where the pump is positioned, how much fuel is in the tank and how clean your suction side filter is as the harder the pump has to suck, the lower the pressure is on the inlet side and the more likely the fuel is to boil and cause cavitation. This is one of the reasons why the problem may be more more likely to occur as the fuel level in the tank lowers.

 

So a good fuel pump installation will have the pump mounted as low as possible relative to the tank to give the maximum suction head. It will have the suction lines as short and direct as possible and generously sized. Any filter should also be generously sized. This is to minimise the suction losses so that the pressure is as high as possible at the pump suction point. For really difficult installations (not TR), a lift pump may be used ahead of the high pressure pump to give it a pressurised feed. It may also occasionally be necessary to use some kind of fuel cooler as a big proportion of the pumped fuel is unused and returns to the tank having picked up heat from the engine bay as well as heat from the pump. This can easily raise the fuel temperature by 20 - 30º and the heating effect gets worse as the amount of fuel in the system falls as the tank empties. For this reason, the "cooling coil" sometimes used on the Lucas pumps has always struck me as an odd device - you really don't want to be adding more heat to the fuel!

 

I can't see a "cooling coil" helping a Bosch pump much as they are internally cooled by the fuel passing through them. Attend to location and feed pipework and they'll work just fine. Best place for the "cooling coil" would be somewhere in the return line from engine bay to tank where it can catch a cooling air-flow.

 

Cheers

 

Nick

[stuart]

My previous Volvo had the old Bosch mechanical fuel injection (Very similar system to the Lucas one) and that had a small lift pump inside the tank combined with the tank indicator and this fed the main Bosch pump which was located underneath the car halfway to the front on a rubber insulated sled with the main filter mounted next to it. That system was superb and even after 225000 miles was still going strong when I got rid of it. You could run that right down to the fumes on the hottest day and it never gave a moments trouble.

The point being mount the pump as low as possible in as much airflow as possible and you shouldnt get problems. Another point to consider that does increase the heat of the fuel is the routing of the fuel pipes up the centre of the chassis through the "T" shirt area right next to the exhaust. If you are still running a Lucas pump with a cooling coil then put your hand on the coil when it has been running for a while and note the temperature. It works the same way as a cooling coil in a fridge. A Lucas pump always runs cooler with an uprated feed and an extra earth strap added as well.

Stuart

Edited May 28, 2010 by stuart

[Ragtag]

All these problems have more to do with the fuel temperature than the pump temperature (except where high pump temperature is directly heating the fuel) and the suction lines and pump position also have an effect.

 

For this reason, the "cooling coil" sometimes used on the Lucas pumps has always struck me as an odd device - you really don't want to be adding more heat to the fuel!

 

I can't see a "cooling coil" helping a Bosch pump much as they are internally cooled by the fuel passing through them. Attend to location and feed pipework and they'll work just fine. Best place for the "cooling coil" would be somewhere in the return line from engine bay to tank where it can catch a cooling air-flow.

 

 

 

The cooling coil was a mod introduced by Lucas to combat the greater of the two 'evils' that you describe. The intention is that the fuel passing through the coil cools the pump motor because this was considered to be the greater source of heat.

 

On my car, which still uses a Lucas pump (because so far it hasn't let me down...where is that wood) the previous owner had fitted a cooling coil but as a stand alone item ahead of the pump. As an experiment, I now have a 2 litre plastic coke bottle filled with water down the centre of the coil. I have never been far enough to be able to make a cup of tea with the contents but the water does warm up so I guess it must be doing some good

[Clarkey]

My Bosch conversion, installed by Mr Talk For Wales, was sounding a bit busy in the heat at Prescott on Sunday. Dark coloured car, no insulation nor reflective over the tank, tank about 1/3 full. Filter is clean, I cleaned it over winter.

Was surprised I must say as we've been through greater heat with less fuel, wonder if it's due to this bio-muck they're now putting in petrol, even in V-Power.

 

Ivor

 

 

Hi Ivor

Thankfully at the mo the Bio muck is only put in to regular unleaded, all the super branded fuels are still Bio free

[Dave K]

Thanks for all the replies guys.

 

Nick and Stuart, cheers for all the info, I think I understand the issues now...

 

Interestingly, I noticed that when my pump runs before ignition, the sound sometimes varies a bit... Sort of high and low tone. OK or bad I wonder... Anyway it's settled down for now.

 

I gather mines an older type Bosch pump, so I plan to keep an eye on it till winter, then update to the latest set up with a better pump location.....

 

Thanks Dave

[RobinTR6]

Have newish bosch pump, clean filters, wider diameter feeder from tank and clean tank. Went to the south of France last year mostly over the speed limit, filled up at Supermarkets and no problem with my pump, yes it was very hot , sunny etc. The tank did get low and apart from cornering the pump remained consistent. Have fittted a relay and pump is well below tank outlet on the outside of the boot weel (TR5 style), anyway cann ot report any probs, heat or 200/300 miles at 80 and then stuck in traffic.

 

If its properly installed and get fed its reliable no question.

 

Robin

 

PS standard Bosch installation from a TR specialist.

[TIMS]

Clarkey

 

From the FBHVC Newsletter No 1 of 2010

 

"STOP PRESS

In the last issue of the newsletter we stated that Shell V-Power petrol was guaranteed not to contain ethanol. Just before this newsletter went to press we have discovered that this is no longer the case. Their statement says: ‘Shell, like many other fuel suppliers, has begun blending ethanol into some Unleaded grades, including Shell V-Power at Stanlow, to comply with the legal obligations of the RTFO’ (Renewable Transport Fuel Obligation)"

 

regards

 

Tim

[harrytr5]

I installed my bosch pump behind the wheel arch and under the boot side upper.I can report no problems with this set up,even in very high tempertures in Italy.It was so hot I had to put the soft top on!.The heat cracked a dashboard(Alan,s TR6).I would probably suggest it could be dirt in the fuel Tank.I put in a stainless fuel tank from the beginning of my restoration with a on/off tap and a tell tale glass filter which I can see at a glance if contaminated.This just unscrews to clean out,very simple and has worked for nearly six years now.The usual suspects,roter arm,cap etc.. having been ruled out I guess.I did have this problem with a fellow TR5 a few years ago and it turned out to be dirt in the tank and starting to block filter/prv.A thorough cleaning out cured it and he has done a huge mileage to date with no more issue,s including Europe.

Regards Harry TR5 Nutter.

[Goswell]

I'm running a Lucas pump fed by a Facet pump, this makes the Lucas pump draw 17% less current, as it's not working as hard as normal.

This means a 17% reduction in heat.

Pump cavitation has never given me a problem though I have suffered cavitation in the engine bay causing missfiring. A Kenlowe fan fixed that.

[88V8]

Another point to consider that does increase the heat of the fuel is the routing of the fuel pipes up the centre of the chassis through the "T" shirt area right next to the exhaust.

Now that's a good point. Prescott was our first real run out with the Phoenix single-box system, and I've noticed that the exhaust pipework gets a lot hotter than the previous twin-pipe as there's less surface area.

So what I should do is pull the petrol pipe out of the T-shirt, wrap it in insulation, put it back. Job for next winter.

 

Ivor

[dykins]

When I had a 6 in the 1980s, we used to always travel with a cool box with a couple of bags of frozen peas inside.

 

As soon as the car stuttered - as inevitably it would - I then opened the boot and put the bags of peas onto the pump. Worked a treat in cooling the pump, but hardly a permanent or professional remedy!

 

I agree with the other postings - keep the tank full of fuel.

 

Fuel vapourisation is karma for all you TR5/6 owners who keep going on about your extra 45-ish bhp over the earlier cars measly 105bhp - at least we know we'll get to our destination on a summer's day! (Only winding you up, before I get lynched!)

 

Regards

 

Peter

[stuart]

Now that's a good point. Prescott was our first real run out with the Phoenix single-box system, and I've noticed that the exhaust pipework gets a lot hotter than the previous twin-pipe as there's less surface area.

So what I should do is pull the petrol pipe out of the T-shirt, wrap it in insulation, put it back. Job for next winter.

 

Ivor

 

I dont suppose anyone has surveyed to see if the overheating fuel problems are occurring more these days with the general use of stainless exhausts and unleaded fuel as opposed to the old days of standard steel and good old five star. I always remembered the old frozen peas trick from the early seventies but we did have better summers then

Stuart.

[fred34b]

Ah, picked the new car up Saturday, nearly 200 miles from home. I thought we might have a little trouble so took out recovery with the insurance (that might of been such as wise move as in hindsight I should of just paid for one of the big boys schemes). We managed to get 30 miles from home before we died totally. I'd also had trouble when exiting islands and left hand bends to the previous 20 miles with the car cutting out but firing up again fairly quickly??

 

I'd read about the pump conversions from the Lucas unit but thought that might be something to look at in the future. However reading below it all makes total sense, probably had quarter of a tank, very hot day, cat in the boot, car died. The car still wasn't going anywhere 30 minutes later and by then the local constab had coned me off, it wasn't the best place to stop admittedly! Recovered to home by another firm as the details had not come through from the insurance company and £244 quid later the car was on the drive. We were going home, the car wasn't going to be sitting anywhere else!

 

Two trips out last night, in the relative cool and just looking at it half a dozen times, £244 divided by eight, worth it!

 

I might be reading up on Bosch conversions before the next heatwave though.