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Fuel starvation when engine is running hot


Smostuart
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On a hot day and usually sitting in traffic my herald 1360 1968 seems to cut out due to no fuel reaching the carb, at the moment it has copper piping from the pump to the carbs but it seems to me that the fuel might be evaporating before it reaches the carb. Any ideas how to sort this problem out? Is it worth replacing the copper pipe with rubber hose or could it be an issue with the pump. Any advise would be great as at the moment it isn't possible to take it on journeys where I might meet traffic. Thanks in advance

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And check there are no air leaks in the suction tube where it joins the tank, this short hose gets hard and

it will suck air but not leak much fuel and being a bit hidden gets overlooked

 

had a local bought a 1300fwd and it cut out every 100 miles on its joirney to a new home

, the fuel seemed hot ,, strange he thought,, as the exhaust needed attention found the bundy fuel pipe

was wired tied to the exhaust pipe so slow was fine but any speed boiled the supply

Briliant or what

 

Pete

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Hello.

 

Is this a recent problem or over a longer period ??

 

Are there any early build-up indications / symptoms before this problem materialises ??

 

Can I confirm your carb set-up for this engine, please ?? 

 

I presume this is the standard mechanical pump and not electric ??

 

Do you have heat shields under the carb(s) ??

 

Thanks.

 

Richard.

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This has been a problem that has been going on for a few years now. As it only happens on hot days (which in this country is rare) but it is getting to the point where it needs sorting. It starts off by juddering as if it was running out of fuel then completely cuts out. this only happens when the car gets hot and temperature gauge is up to about 3/4. It doesn't happen when the car is moving as engine is being cooled. It won't start again unless you either let the engine cool completely or suck the petrol through the hose at the carb end. As far as the carb is concerned it is a single carb pretty bog standard for this engine. And yes it is a mechanical pump. Not to sure about heat sheilds pretty certain it hasn't got them but at some point this was never a problem so personally I would think I could rule that one out also what sort of tests can I run on a mechanical pump to check it's working correctly. thanks again for the comments all very useful

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Hello.

 

You can pressure test the output of the mechanical pump, provided you have the correct gauge to hand - if not you will need to purchase one. However purchasing a gauge is money spent towards a new pump which are not that expensive !!

 

The alternative is to buy a pump rebuild kit, but that will not deal with any wear in the pump itself of which there is likely to be some if the unit is getting on a bit.

 

As a matter of interest when the car cut out did you at any stage undo & take-off the fuel cap to allow air in to the fuel tank ?? I ask this in case there is a vacuum problem within the system and as the temperature increases so the vacuum increases, which may prevent fuel being delivered to the carb.

 

For the moment I would concentrate on the fuel pump. If this proves to be at fault problem solved I would say.

 

Other options to consider are re-routing the fuel delivery pipe taking it away from the usual heat sources. whether you do that or not I would recommended when doing your fuel delivery overhaul to incorporate an in-line fuel filter and a non-returnable (one way) fuel valve; if not already deployed.

 

I presume the timing is correct and are you using electronic ignition or standard set-up ?? If standard set-up, is the rotor arm up to scratch (some poor units about)  and are you happy with the points & condensor ??

 

Worth just flagging up the coil, does it get super hot when the car is running or just tepid ??

 

Finally (!!) Is the car running unleaded on a converted head and who do you purchase your fuel from - I ask this in relation to ethanol percentage ??

 

Hope the above assists.

 

All the best.

 

Richard.

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This would be a single stromberg 150CD

if younadded a clear hose to the carb you will see if you have lots of bubbles, trouble is air leak and vapour look the same

 

 

to get a rough idea about pump performance, with engine idling on a float full with hose disconnected a good well defined spurt into a jam jar is expected

 

the engine will run on a float chamber full and it can pump a good 1/2 pint quite quickly

If you only get a cupfull its sick.

 

way back we had to pump fuel from commer vans with the rootes 1725 engine ,and glass top AC pump. we made tee off the fuel supply and drained fuel while driving, it took about five minutes to fill a gallon can

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Apart from this has the call of fueling, Richards clue on the coil is a good call

many get wired with wrong polarity , it overheats , it stops,, get out kick a few things twiddle anything

you can , get in it starts ,

this plagues many a coil, make sure the -ve has the dizzy lead and +ve has the ign feed (neg earth car )

 

Pete

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Right bit of an update on this issue, I have changed the fuel pump for a brand new one, the first thing I noticed is that the performance of the car had greatly improved I then let the car run up to near hot on the temperature gauge and not once did it cut out, I then took the car out for a drive and I noticed that it was running very lumpy but again it didn't cut out. It was like it still had a slight starvation problem. Also I took the fuel filler cap off and there was no vacuum at all. As far as the coil is concerned it is a brand new uprated coil which has been checked and is putting out the correct v along with electronic ignition which runs perfectly and doesn't miss a beat in normal circumstances unlike the old points system which was on the car. Also I took the old pump apart to see if I could see anything obvious. One thing I noticed is that there was a lot of debris inside the pump which I suppose could acount for the poor performance. Thanks again for all your suggestions. Stuart

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Hello Stuart.

 

Do you have an in-line fuel filter and if so where is it positioned on the fuel run ??

 

If not, you should use one.

 

I think from what you are saying that the old pump has probably collected a lot of gunge and you need to determine where this has come from - probably the fuel tank or perhaps your fuel pipe is starting to decompose. An in-line filter will deal with 99% of the gunge and if possible I would suggest placing a filter between the fuel tank and pump if possible. Quite often that is not possible, so between the pump and carb is your next best option.   

 

Replacement fuel hose should now be R9 spec and not R6. R9 is constructed to deal with modern day fuel and is resilient to ethanol.

 

Thanks.

 

Richard.

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Sounds good advice currently there is no fuel filter so will get one ASAP been on my mind for a while anyway. It will have to be positioned between pump and carb. Pretty certain that this won't solve the issues but will won't do any harm only good. Can anyone see a benefit of replacing the copper pipe between pump and carb with rubber hose as surely this won't get hot and evaporate the fuel any other ideas definitely welcome. I won't stop until this issue is solved lol

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there's loads of room in the boot of a herald/vitesse, , so replace the suction hose out the top of the tank , maybe make a bit longer   

 

while you in there check the sleeve nut that seals the tube to the tank under the reserve handle  inside this union is a simple rubber olive

these can leak on a full tank ,  you can cut a new olive from some feal hose.  as said this are is bit hidden and gets ignored 

 

Pete

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As you've got crude in your fuel pump I'd blow out your fuel lines with an air gun/pump or, Dyno Rod them with strimmer cord. I used cord and forced out a load of pink sludge which was partially blocking the fuel line and occasionally causing a total blockage.

 

I've replaced all the pipes between pump and carbs with hose. Easy to route away from hot stuff and saves all the worries about the dreaded rubber slivers getting into the carbs. I would place the fuel filter before the pump, as it's easier to get crude out the filter than the pump!

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