won't start - now intermittent loss of power

[LouiseM]

Flushed the radiator and checked the thermostat. Lots of 'rusty crud' in the thermostat housing and top hose. The 'stat is an 82 degree one. I tested it by putting it in boiling water but there didn't seem to be any change, other than it looked cleaner! Which bit is supposed to open & shut?

[tysonn]

The bit in the middle.

[LouiseM]

Thanks. Nothing was 'open' when I took it out. Here's a few pics:

What it looked like when removed:[frame][/frame]

Immediately after removal from boiling water:[frame][/frame]

I guess I need a new thermostat!

[bmcecosse]

Doesn't look like the correct type - I suggest a 74 for summer use. And a new gasket of course.

[les]

Yes, usually the centre part will separate from the outer surround by about 1/4 inch/6mm. Time to bin that one!

[LouiseM]

Not been able to work on the trav for a while as I've been working away for a few weeks but finally got round to fitting a new thermostat, gasket & housing and also replaced the top hose. Took him for a run today and the same loss of power occurred around 5 miles from home when travelling at around 60mph. Started running fine again once I had dropped the speed to 50mph and there were no further problems running at 50mph or less for a further 10 miles or so. I know that a new dizzy was suggested a while ago but before I change the polarity to negative earth and fork out for a new one just wondered if anyone had any other suggestions? (besides not driving over 50mph!).

[bmcecosse]

And it's definitely not a vacuum in the tank? Maybe an obstruction in the tank - restricting fuel flow. An 'ignition' fault would surely show as mis-firing/cutting out etc rather than just loss of power - which mysteriously is ok at less than 50 mph. These symptoms seem to show fuel supply difficulties to me...

[LouiseM]

I'll take another look at the fuel supply but if there was a blockage of some sort why would it disappear when running at a lower speed?

[aupickup]

mystery
cant be much wrong

[alexmcguffie]

Louise,
Your fuel flow will be less at lower speeds/throttle openings. It may not be a total blockage but a restriction somewhere. Check the fuel pump filter and take the lid off the float chamber to see how much silt is at the bottom. The fuel pump filter isn't the best in the world.

If the problem is in the tank, disconnect the pipe off the fuel pump that goes to the tank, put some rummer hose over it and blow down it. This will, in effect, back flush it. The dirt causing the blockage will still be in the tank but after a drive it might show if the problem has improved.

[LouiseM]

Thanks for the explanation Alex (did you mean 'rubber' rather than 'rummer' hose?) I'll do as suggested and report back

[alexmcguffie]

Yep, rubber hose!

[bmcecosse]

Blow - don't suck.... The fuel flow test is to measure how long it takes the pump to deliver say 2 pints of petrol into a container. Consider the car doing 30 mpg at 60 mph. So 16 pints per hour ~~ 4 minutes per pint. Do it over 2 pints just to be sure - if it doesn't beat 8 minutes........

[alexmcguffie]

I'm sure I said BLOW above... Depending which spec you read for the fuel pump you should get between 8 and 9.2 gallons per hour with no back pressure (open pipe).

[bmcecosse]

Yes indeed - I was just emphasising the need to NOT suck.... But be aware there may be a reverse pulse down the line when you stop blowing....... I would run the test with the top of the float chamber still attached to the pump delivery pipe - to check if perhaps the obstruction is in the float valve.

[LouiseM]

Don't worry, I'll blow not suck!

[GBond]

I was having a similar problem with a Triumph, hardly used the car for over a year because of this and just yesterday night tried blowing on the fuel line from the pump to the tank and indeed it was very obstructed. Used the compressor to blow a bit harder and that apparently cleared the obstruction.

However, I think it will be better to empty the tank and clean it to avoid the line from being clogged again. Hope the fix is equally simple for yours!

[liammonty]

Is the coil wired up the right way round? They'll run for a time wired up 'backwards', but the coil will overheat after a while and cause a misfire. I've had it twice, once my fault after I'd changed the engine on our 62 saloon and hastily connected the coil up wrong, and more recently the error of a previous owner on my Wolseley 6 landcrab...

[LouiseM]

To update on this, I broke down again on the way to the National with similar problems - loud back firing, loss of power then coming to a complete stop with problems getting the car started again. Got lots of help and advice and the general view was that it was an ignition problem. After replacing all parts one at a time (points, condenser, rotor arm, plugs, leads, coil) everyone was stumped. An electric dizzy was fitted and the car started up fine but then stalled. It turned out that changing the polarity to fit the dizzy meant that the fuel pump no longer worked. A new 'non-polarity sensitive' pump was fitted and the car was then running really well - also had a carb tune on Sunday morning.

However there is still a problem when driving at over 50/55mph. The car starts 'stuttering' and loses power but going back down to 50mph it runs absolutely fine with no problems. It also seems sluggish going up hills and having looked at other posts here could it be a valve problem? Mike Perry noticed that the exhaust manifold fit wasn't great but not sure if that would cause the symptoms? No signs of a head gasket problem and an ignition / fuel problem has now been ruled out. Any thoughts?

[bmcecosse]

Hmmm - was it a new pump fitted - or an old one? Compression check will confirm engine condition, but do set the valve gaps first (and 15 thou exhausts) . The 'backfiring' instantly confirms there is fuel going through unburned -so it was an ignition problem. Strange that changing everything didn't sort it....perhaps it was the coil...