14 RE 150c Trouble with hot starting

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14 RE 150c Trouble with hot starting

Post by tranentbx » Sun Jul 13, 2014 8:39 am

Hi folks,

Have noticed this problem for a while now. Car starts and drives fine except if it's hot. But here's the weird thing, if I turn it off (when hot) then start it again immediately - no problems.

It's only if I leave it for say half an hour or so that it really struggles to start again. Taking a good 15-20 seconds of turning over and giving it a bit of gas before it splutters into life, then away we go as normal.

Once left to go cold, motor starts on the first turn again.

Any ideas where to look?

Weak mixture? (runs 95 unleaded but should it be LRP?) I've used both in the past and can't notice the difference when driving

Problem with carb? Float level?

Just guessing here so need the experts!

Cheers guys

Pascal

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Re: 14 RE 150c Trouble with hot starting

Post by citsncycles » Sun Jul 13, 2014 9:43 am

First, those early 14 engines should be using an additive as they weren't designed to run on unleaded, but you may get away with it if driven carefully - depends on what you use it for I suppose.

Your starting problem may be fuel vapourisation - check the routing of the fuel line is well away from the exhaust. Also check the insulation block under the carb is ok. It may be worth fitting a heat shield under the carb too if not already fitted.
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Re: 14 RE 150c Trouble with hot starting

Post by Tinkley » Sun Jul 13, 2014 11:20 am

Well I could definitely feel the difference between 4* and LRP..., never did try 95 unleaded as it was not designed for it. Car manged 175k so it was not so bad a unit, with one major rebuild. An additi

These Solex carbs are pretty easy to strip and clean, and I would do that. With the manual choke it simplifies things. Also check the engine crankcase breather is not filling the air intake with 'mayonnaise' because this can block the jets - usually the primary main. I assume the air box is on summer (ete) setting, so check that if not on that setting. I used it all year round unless exceptionally cold. So a screwdriver and a can of Carb clean should sort it out. If not change the HT leads, as these engines just eat them, I used to reckon if I changed plugs, I had to change leads as well. Any light misfiring under load or slight fall in fuel consumption and it would be the leads.

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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Sun Jul 13, 2014 11:41 am

Thanks, couple interesting things thrown up there. Air box was on middle setting ( neither winter or summer) now changed. Will see if that makes a difference. Didn't actually see that till today!

Will definitely go back to fuel additive.now to be on safe side. Only do thousand miles a year max.

Fuel line well clear of block/manifold.

HT leads brand new last summer and no corrosion I can see....

As for mayo, none in breather pipe and carburetor looks clean as a whistle from top with air intake off. Is it worth taking apart?

Think I might see how it runs on the summer setting and with additive to start with.

Then I'll see about fuel vaporization? Apparently you can get thicker gaskets which are better insulated?

Cheers

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Re: 14 RE 150c Trouble with hot starting

Post by Tinkley » Sun Jul 13, 2014 12:17 pm

The carb is very easy to strip, just be careful easing the top part from the lower part as you do not want to tear the gasket. As idle and the lower part of acceleration uses the idle jet as part of the mixture it is worth a 'blow' through. You may even find the mount screws to the manifold have become a bit slack. Mike is quite correct about the gasket thickness. My own car was a late one an a 1988 (April) 14 so already had the thicker gasket. If you have an early 14, it may well have a thin gasket. Citroen definitely changed the gasket thickness to help remove this vapouristaion problem. Double stacking the thin gasket was I believe also done by some techs prior to the thicker gasket.

The later TU unit is not as bad at directing heat under te carb so less of an issue. My current 1.6 has some vapourisation traits but mostly from the slightly ageing autochoke and when at an in between temperature mode rather than hot or cold.

I don't remember too many problems on hot starting, and the 'mayonnaise' is more of a cooler weather problem - try cutting out at 70 on the motorway with a blocked (main) jet for fun. Yes in this weather the summer setting should be used, btw it is more economic to use 'cold' air as it burns more efficiently, and yes, you can notice better fuel consumption at least when you run the car a reasonable ammount say 10k plus per year. These units should do anything between about 37 -50 mpg and right now in this temp about 40-41 for general running around, shortish runs. If you want 50/51 mpg, you need to get it hot and keep it below 65..... :wink:

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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Sun Jul 13, 2014 5:08 pm

Hi Tinkley, thanks for the additional info. Mine is also an April 1988 model so must have the thicker gaskets. I think ours was the last of the suitcase engines?

In terms of mileage, I'm getting roughly the same numbers as you mention ( based on my weak grasp of maths )

I'm only at 67,000 miles so mine is a relative spring chicken!

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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Tue Jul 22, 2014 8:54 am

Hi,

Just for a week update.

Now am only using fuel additive with unleaded and running with the air intake in summer position.

I have noticed a slight improvement in hot starting but am still having to pump the gas pedal a good bit to get it going...

Wondering now if I should actually be using the choke a bit as the engine may not be as hot as I think it is after 20 minutes to half an hour.....

Will keep experimenting....

Cheers

Pascal

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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Mon Apr 20, 2015 6:37 pm

Hi folks,

Just wanted to say I'm still having the hot starting problem and have another theory to put to the experts :-)

I wonder if the fuel is draining back into the tank after a while and that's why it takes so long to start. I've been watching the fuel filter (which is see-through) when I crank the starter. It does take about 10-15 seconds for it to fill up and get through to the carburettor and then start the car.

One problem with that theory is why does the car start first time when cold?

On the supporting side of my theory, if you stop and start the car quickly (when its hot), it will go no bother. This is before the fuel has a chance to drain away though! Is there a way to fit a non return valve to the fuel supply? Can I rule out a problem with the carburettor?

Does any of this make sense?!

Thanks

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Re: 14 RE 150c Trouble with hot starting

Post by Thread Bear » Mon Apr 20, 2015 7:10 pm

If this is a diaphragm lift pump they can become poor performers. Not helped by the new fuel additive ethanol. If it has a hole in the diaphragm it will not be working well. In some designs the petrol can get into the sump - like NSU, and blow the crankcases apart! Certainly it will pollute the oil. Others it just vents.
Likewise most pumps have a one way flap valve to slow drain back and promote self priming. If this is up the creak then it will exhibit the issues you describe. However I do not know if the BX pump is one that has this.
If like a Fiat with a return pipe from carb float chamber to tank, that can become blocked. Vaporising fuel will not be able to get out and push the fuel back down the main feed. Such systems tend not to vent to the atmosphere, but are sealed. A classic small Fiat problem, exacerbated by fitting an in line filter. Often these cars are run thus for some years and burn out as they for ever run weak and hot.

Having made a copper HT lead set for my 1.6 petrol carb car, I can vouche for the amazing difference it made over the rubbish on sale from the motorists shops. Other than play in the choke flap, that occasional gets stuck in the shut position, the car starts instantly now, on the auto choke.
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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Mon Apr 20, 2015 8:03 pm

Thanks Thread Bear,

I can confirm that the fuel pump is of the rubber diaphragm design. I've had the fuel pump apart last year to investigate. The rubber did not look holed and the whole thing seemed to work well (squirted fuel half way across the garage) Of course this doesn't mean it's in top form I suppose...

Another point I should have mentioned. The MOT was done today and it passed the emissions test no problem. In fact the result was only 0.49% which the mechanic did mention was extremely low. Most modern cars put out 0.25% but he was expecting between 2-3% for my car. Is this is a sign that it's running very lean? I think so.

The fuel may well be vaporising as you say and forcing it back down the pipe and back through the pump. Is there a case for refurbing the carb? have seen a kit on ebay for £35. Is that a dangerous plan!?!?

Is the LRP additive I put in no good?

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Re: 14 RE 150c Trouble with hot starting

Post by citronut » Mon Apr 20, 2015 8:35 pm

the fuel can not drain back to the tank from a carb float chamber as it works like a toilet cistern, the fuel in is above the float level, even on a car with a return to the tank line, this only collects un/required fuel before it enters the float chamber and not after,

i havent re/read through this thread, but i might have already said, 2CV's suffer hot starting issues if the float level is way to high,

i do agree with Mr Thread Bear the BX does suffer with over choking, in my experience this is caused by people twidling with the adjustment without knowing how it works,

another cause of this is either insufficient coolent in the system, so it does not reach the wax stat for the choke, or the coolant hose nozzles for the choke wax stat become blocked with corrosion,

the BX choke shuts very quick after the engine is switched off

regards malcolm
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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Mon Apr 20, 2015 9:10 pm

Thanks Malcolm,

I haven't touched the adjustment screws myself (but thats not to say the previous owner didn't). The only thing I've done on the carb is spray cleaner through the air intake and lubricated the choke mechanism (It's a manual choke by the way so that might discount a few things?)

With regards coolant, I flushed, drained and refilled the whole system last month and replaced the radiator too which was leaking slightly. I got 6.5 litres out and put 6.5 litres back in (After a lot of bleeding)! I can confirm the thermostat works as does the fan. I don't think it's running particularly hot. The fan will kick in when in stationary traffic but doesn't stay on for more than 10 seconds or so.

Can the float level be adjusted if its too high? how would you know it's too high?

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Re: 14 RE 150c Trouble with hot starting

Post by citronut » Mon Apr 20, 2015 10:04 pm

as you say youir car has a manual choke this then discounts the coolant theory, as the wax stat i mentioned is on the carb if it were an auto choke, and not the coolant thermostat,

the problem caused on a BX with an auto choke and low cool;ant is, the coolant does not reach the choke wax stat on the carb, so the choke stays closed

the only way to check the carb float level and likewise float settings is to remove the carb lid/top

regards malcolm
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Re: 14 RE 150c Trouble with hot starting

Post by Tinkley » Tue Apr 21, 2015 8:19 am

I doubt there is much wrong with the carb in fact. However my 150C engine got better CO content than yours something like 0.15% and one place kept telling me the engine would blow up - it never did!. My 1.6 is similar so 0.49 is something I would consider bad for a 150C!!!! Actually it could easily be a dirty air filter or a not just cleaned carb.

The hot starting is different from the auto choke 1.6s. If I remember right, I used no (manual) choke, a couple of presses on the throttle prior to turning the key. The issue is more fuel vaporisation, as the carb sits on the inlet which gets warm when the car is stopped after really heating up or in standstill traffic. It simply evaporates the fuel in the bowl and line to the filter. Letting it pump through a bit and light pedal pressure should see it start. Especially as there seem to be no issues on a cold start. Just a quirk of the 150C, my 1.6 requires fully depressed pedal (auto choke) and still can take up to 20 seconds of turning to start if it is hot... :wink: Note - do not use this technique on the 150C, it will flood it.

The carb if Solex is easy to strip, straight flat head screws not Torx which I have on the later model. 5 of them hold the top half to the bottom, but be careful on separation not to tear the intermediate gasket. The float level is I believe set by removing carb and turning upside down and measuring the distance from float to the base of the top half of the carb. The Haynes gives 33mm for Solex 30-30 Z2 CIT348 which should be your carb. I doubt it is out, however some tit had altered one of mine (1.6) to 40 when it should have been 33 and it failed on emissions - mainly because of this. Also why I think yours is OK.

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Re: 14 RE 150c Trouble with hot starting

Post by tranentbx » Tue Apr 21, 2015 10:28 am

Tinkley, thankyou.

The air filter is new so will discount that.

The carb could well do with a strip down. Apparently my car has the 32/34 Z2 Solex. There's a kit for that on ebay with new gaskets and diaphragms etc. Is that too much of a risk though in amateur hands?

I will just put it down to fuel vaporisation as this is the most logical cause. The car runs fine otherwise. I wonder if there's a way to keep the carb cooler? ie. wire a fan next to it :-) It already has the thicker gasket between it and the block.

Is there a way of fitting a none return valve on the fuel line so the fuel filter at least stays full? That would save a lot of time on start up. I'm wondering if the fuel filter I put on should have had one. Perhaps the original one had this already?

Anyway, thanks