Herald 1200 Fuel overpressure/excessive consumption/Malpassi Filter King regulator...

[Morgana]

Hello TSSC members. I've very recently got my first classic car - a 1966 Herald 1200 - and have done a lot of replacement and adjustment (new tyres, fuel sender, headlight relays, properly gapping the sparking plugs, valves and points etc.). However, I've still got a fuel problem.

When bought, the car seemed to be very thirsty and the fuel seemed to disappear. No leaks are visible, but we noticed fuel pooling on the throttle butterfly after switching off. We tested the pressure, reasoning the fuel must be ending up in the manifold, despite no sooty plugs or black exhaust, if it wasn't leaking from the pipes. It was up at 9psi, and the manual says the Solex only needs ~2psi. I'd read about the wrong-spring-in-the-fuel-pump problem and how this can overwhelm the float valve, so thought it was an opportunity to insert a Filter King to add a fuel filter, at the same time as regulating the pressure down to something the Solex B30 PSE1 could handle.

The problem with the Filter King (secondhand 67mm glass body, new diaphragm, filter, spring, seals and washers) is that it appears to regulate between 5psi and zero with the tiniest tweak of the screw. One way the engine dies from starvation, the other it's still too high a pressure. The valve in the Filter King moves freely on its spring. I've got the fuel pressure gauge on a T piece between carburettor and regulator, and have tried two different gauges. The Filter King has been mounted by the coil, and plumbed in with new Gates Barricade 1/4" hose.

The carburettor has been dismantled and cleaned according to the manual, with new gaskets, a new strangler rod to replace the cracked old one and all jets checked. There was no ball bearing in the swan-neck recess, so we replaced that. All new Solex parts are from Gower & Lee. The float is OK and the float valve works (blocks air when blown into with the float chamber lid off and the valve operated with a finger). The carburettor's obviously had a hard life, with one screw replaced with a metric setscrew and nut, and one other hole has the thread on its last legs. However, there's been nothing visible dribbling from the carburettor.

The engine idles well with ~19" vacuum.

Any ideas as to where my fuel is going, and whether I've done something wrong with the Filter King?

[Casper]

Welcome to Herald ownership, and the forum.

The fuel 'leak; after use is not uncommon due to 'heat sink'.  Apart from that all I can add is that the pump is not OE (but you probably knew that from your research. 

Factory recon engine?

C,

[johny]

I would rather have tried to cure the pumps excessive output pressure than to add another variable like a pressure regulator. Fortunately there was a successful resolution of the problem posted on here recently and it concides with the instructions in the Triumph workshop manual for installing a new pump. It is to make up packers to fit between the block and fuel pump so that its operating arm is moved further away from the cam that pushes it. This then reduces the compression of the spring so that the force it applies to the diaphragm is less and the output pressure generated drops. It is a trial and error process but the poster didnt find it difficult to get the correct pressure... 

[Pete Lewis]

there are a couple of out the box fueling ideas 

yes 2psi is really the best start i would cut the pump spring down or if you have the old pump swap the springs to get a lower PSI

have you checked the speedo oddometer rolls  if they are not recording correct mileage covered you get silly consumption results as the miles are ...miles out 

you changed the float  should know but  brain fog  are your gauges stabilsed   IE  needle moves slowly when switched on ???

two things here   fit the wrong sender and you get daft tank readings

the voltage stabiliser has failed gives you  very odd fuel tank readings 

ifyou have moving iron gauges  ( needle flicks up to a reading as switch on ) you dont have a stabilser but do need a matched tank sender

so there are a few things that may be colouring your thoughts   it may not be  engine related 

Pete

[Morgana]

Thanks all, and for the welcome Casper. I'm not sure about the engine. It's got a 'Stanpart' plate on the left, but I've not found a table to explain what it means in comparison to the engine number codes floating about online, which seem to be a different numbering system.

The Filter King just seemed like a good way to get a filter into the system as well, and it's such a simple mechanism I thought it peculiar that it would be the problem. Thank you for the suggestion johny - I saw that bit in the manual about adding gaskets. That's probably tomorrow's procedure. I did come across the thread you mentioned, but there was no final record of the thickness required. I suppose OE fuel pumps would have been out of kilter by rather less than five times, but it's good the same technique works when it's off by miles!

I have a few different sheets of gasket paper (the thickest is 1.5mm). The previous owner said they'd put in the new fuel pump, but unfortunately the one that came in the spares is another reproduction type with a spring constant of -1.48 (as calculated by callipers and a kitchen weight). I don't know what the original should be, and despite quite a lot of online digging I've not found a spring supplier that can supply one of the same dimensions but a lower spring constant.

That's a good thought, Pete. The car came with two speedometers and gauges. One stabilised, one not. The non-stabilised gauge was installed, but connected to the stabiliser, and having sorted that (I had to adjust the stabiliser and calibrate the gauge with a bench PSU as well), it was still failing to read. It turned out the sender was a modern-manufacture 3-180 Ohm type, which corresponds to no Triumph gauge ever made as far as I can make out. I got a new made-in-UK Caerbont one (20-240 Ohm) but the holes don't line up as the tank has a hole at 12 o'clock and the sender's upper one is off to the left. I had to drill out one of the spot welds and bend the potentiometer bracket across to be vertical when the sender was screwed on. Now it reads properly. Before, the engine just died after a few local journeys and the tank was empty, so it wasn't a case of the odometer reading low (unfortunately!) We've got a jerry can in the boot at all times.

I've filled up today and reset the odometer.

[johny]

The fuel pumps were never made by Triumph so even back in the day different makes were fitted when the original failed and the manual fully expected there to be variations in output pressure which is why it made the recommendation of packers. The spring may even weaken with use and the packer need reducing to maintain sufficent pressure. From the mentioned thread I dont think it took much thickness to get quite a large drop in pressure... 

[johny]

The original post by unklekunkle had a pump giving 7psi and then when fitted with 2 paper gasket and a 1.5mm spacer that dropped to less than 2psi. He ended up using just the spacer to give 3psi...

[Colin Lindsay]

That's a proper Stanpart exchange engine... not many of those survive with the badge intact.

[Pete Lewis]

i once had a Maxi which gave awful consumption until a 210 mile journey to torquay only took 140 recorded miles 

you cannot mix and match the two gauge systems  thats fuel and temperature  each to its own dedicated parts 

stabilised has its own set of gauges and senders  needs this as voltage variation changes the readings 

non stabilised   has its own   moving iron  gauges do not need a stabiliser the gauge takes care of voltage variations 

there is no way you can intermix the two very differing systems  

have you pulled a spark plug if its drinking fuel you should get some sooty plugs ???

Pete

 

[Tipidave]

I have read about your experience with great interest. Almost exactly the same situation as I have experienced. I too put in a pressure adjustable fuel filter for the same reasons.  Although largely I have now solved the problem of fuel leaking into the manifold, I think that the comment about keeping things standard and adjusting pressure from the fuel pump is probably the way to go together with copper fuel pipe from pump to carb.

I think that we have unwittingly contributed to the problem due to the increased volume of fuel in the system at whatever pressure is set (fuel at 7 psi can slowly leak through the filter valve once stopped).  If we take the fuel filter out, then the residual fuel volume in the fuel line at 1-2 psi will only be a few ml… and if it does break through  the float valve will not cause too much of a problem. 

There is one other important aspect to this… the solex carb float valve was installed in many variants of carb and required a different thickness of washer under the float valve… this has an impact on how full the bowl is when the valve cuts out. Couple this with the lower specific gravity of modern fuels and the tendency is for the bowl to even more full. Turns out that even a very small variation in level can have a big impact on the richness of the idle circuit and also contributes to the tendency for residual fuel to overflow. Make sure that you have the correct thickness of washer installed. (There is an article on this in one of the 1980s Courrier magazines). Also, do not assume that the valve is the correct diameter I think that a 1.3  is specified but a valve with a larger surface area seems less susceptible to leaking. 

Also, as Pete so wisely told me  in a reply, tiny slivers of rubber do have a habit of breaking free from the fuel hose and causing the valve to seat incorrectly. So when disturbing the flexible fuel hose take great care to flush through before re connecting.

I have experimented and now use a 1.6 valve with a thicker washer and have more or less resolved the issue.  I think that I will go on to remove the adjustable filter and correct the pressure at source with a thicker gasket as described elsewhere. Good luck with your solution. It is very frustrating but can be solved. 

 

[DanMi]

That is a factory recon engine with standard bores with grade F pistons, standard big ends and 30thou undersized mains, or at least it was at some point in it's life, it could have of course been rebuilt since. FR suffix = factory reconditioned. I have no idea about the AT prefix

[Wagger]

You have not stated what the actual consumption is (or I have missed it). Fuel will evaporate from the carb after a run, especially if the bowl gasket leaks. It does not always exhibit this when running because, by the time you have opened the bonnet, any spillage will have evaporated. Over pressure can make fuel enter the inlet manifold after switching off, and that will evaporate through the open valves and/or drain into the sump.

On my Vitesse 2.5 Litre, I replaced gaskets, hoses and floats and the consumption is now between 20 and 25 mpg and I have only done trips to the shops, so far. Before, I used two gallons just running up and down the drive in less than two weeks. The smell was the 'Give-away'. All seems well now.

[Morgana]

Thank you all. I'm revisiting this after it seemed to be OK for the last few months. Though the car was running the pressure was still too high, but a tank of fuel wasn't vanishing into thin air. The response to my new surging problems is surmised to be fuelling so I'm re-reading this thread.

I spaced as much as I could behind the pump but one stud is shorter than the other and the pump can't be moved out enough before the nut can't be put on. I haven't dared attack the studs yet in case they're seized. One is not a stud at all, but a screw so there is an oil leak which I think is along this thread despite some thread lock.

Tipidave - do you know which magazine the information about the washers is in? I see I can download archive magazines from the website but don't want to trawl through the whole decade if you're able to help narrow it down! The last time I had the carburettor apart the valve was working when blown through. I don't know what size the valve is.

Thank you for the engine information DanMi.

Wagger - the fuel was disappearing similarly to your experience. I didn't measure the consumption as it was just disappearing. A recent trip this summer after all this fettling, Cornwall to the west coast of Ireland, was in the mid-30s mpg.

[steveo]

My 13/60 is running a small electric fuel pump, no idea of pressure it works at, but the car runs perfect and never had a problem, maybe this is the way to go on yours ?

[johny]

Trouble is you could go to all that work (wiring, plumbing, cut off safety switch etc) not to mention cost and still be no better off☹️

[NonMember]

21 minutes ago, johny said:

Trouble is you could go to all that work (wiring, plumbing, cut off safety switch etc) not to mention cost and still be no better off☹️

Indeed. I've fitted electric fuel pumps to a Triumph twice. The one on the Spitfire made no difference to the problems it was having - because the problem was the tank. The one on the Vitesse did fix the original trouble (it had a 13/60 pump and suffered vapour lock whenever the engine got warm) but introduced a pile of others. It now has a proper glass bowl mechanical pump and all is good.

[Jon J 1250]

I have seen quite a few discussions about problems with modern replacement mechanical pumps, just out of curiosity isn't rebuilding the original AC pumps an option, kits are available?

Jon

[johny]

Yes its an option but the kits are a good proportion of the price of a new pump and also changing the valves in the old unit is a bit fiddly which puts some people off overhauling.

If going to an electric pump I think the time to do it is when the engine is running perfectly so that if theres any change you know its probably down to the modification....

[Pete Lewis]

the kits are available  but some AC pumps have the valves staked in place and removing old and refit new can be a challange to suceed

depends on your diy skills  

early pumps the valves are held by plate and screws   much easier 

replacing the diaphragm is easy on both generations of pump 

most aftermarket copies have excessive pressure as found by so many on here 

swap or shorten the pump spring does correct the excessive output 

be aware fake/cheap fuel hose can make the dreaded rubber slivers as you push the metal pipes into the hose 

Gates barricade is sold by club shop and others and its tough doesnt shead slivers to block the float needle valve  and give you troubles 

Pete

[Wagger]

Added this as I cannot find where I posted it before.

After many fuelling 'Events' I discovered a squidgy piece of rubber pipe a third of the way under the car from the rear. After standing for two weeks the fuel line was dry, so the car would not start or run. Sucking at the carbs using an electric pump achieved no fuel. Sucking from the tank did. Pumping from the boot showed a leak under the car.

Had to watch this as it was almost unbelievable. The squidgy bit was collapsing when sucking from the front and 'Ballooning' under pressure. This had caused several hiccups as the car would run if I primed the system. It was collapsing under slight vacuum and blocking any flow.

Needless to say, all pipes are replaced now and all is well. I use the glass bowl pump and managed to change the valves by 'Peening' them in. I used a small punch to do this. Removing the old ones is a 'Dig out' job. Have to be careful not to damage the casting.

[daverclasper]

Not read all the details on this thread, though reading previous, it may be that 3mm-5mm spacer/gaskets has solved issues  

[Unkel Kunkel]

The original manual information deserves looking at:

This worked.

However,I had already ordered a Filter King -So I used it too.

I think they are a good choice.

- they, also have a  filter in a visible, easily changed, “period” fitting.

[Morgana]

Yes Unkel Kunkel, the Filter King was added partly as a fuel filter. However, there is still the problem of it failing to regulate despite a new diaphragm (the Filter King was secondhand). It is either on or off with the slightest turn of the adjustment screw at the crossover point. When fuel can actually come through, there is too little thread visible for the acorn nut to fit. It's one of the things I'll look at today. As per my earlier post, I have maximum gaskets under the pump as I'm on the edge of running out of thread on the mounting screw.

Pete Lewis - you recommend shortening the spring a couple of times. Does this really work? I would have thought the spring length is important to support the diaphragm, and the 'correct' spring would be the same length but a weaker spring constant. Is shortening the 'throw' the diaphragm moves through OK, without wearing the diaphragm excessively?

Wagger - There's no complete starvation, but I will check this pipe. I went over all the flexible pieces between tank and carburettor earlier this year and discovered nothing untoward, but one never knows...

 

[Pete Lewis]

shortening the spring is not something ihave tried but it has been used by a good few members on here over the years 

keep the cut end on the  base casting rather than the diaphragm disc but it wont affect much other than the output pressure 

how much to trim off is........... unkown trial and error 

Pete

[NonMember]

2 hours ago, Morgana said:

I would have thought the spring length is important to support the diaphragm, and the 'correct' spring would be the same length but a weaker spring constant.

What matters is the fitted length being sufficient. The fitted length of a (compression) spring is nearly always shorter than the free length, by an amount that is set to get the baseline force. The spring constant determines how much force is needed to compress it further. So as long as you don't shorten the spring to below the fitted length it will still support the diaphragm but will exert less force and thus generate lower fuel pressure.