1800: Hard starting overnight

[asneddon]

I have a bit of trouble starting my B18 P1800 first thing in the morning. At all other times its normally right on the ball.

I've replaced the plugs/leads/points/condenser/rotor/distributor cap/air filters.

I removed the single fuel filter as it was full of crud. It was at the back between the fuel tank and solid pipe. I will fit one at the front before the fuel pump when I manage to find the correct sized fuel line.

I've tuned and balanced the carbs (twin HS6s) and they seem in decent condition. The pistons go up at the same speed, and drop more or less in sync. There is ATF oil in the pots.

When starting it in the morning it will fire on the first turn but not catch. Then it takes a lot of winding to get it to catch. This first catch will run very very rough and won't come right. If I get to this first catch, turn off the ignition, then restart it will run perfectly.

I've tried lots of different choke settings when starting, from full off to full on. Doesn’t seem to make much, if any, difference.

I haven't pulled the carbs apart yet as I don’t get much time outside work at the moment. One thought is the float chambers leaking fuel out over night.

I also haven’t replaced the coil, but I doubt its that as after this first start everything seems to be good.

Another thought is the fuel running back from the carbs to the fuel pump, needing a little wind to get back to the carbs. This doesn’t explain the weird first catch symptom though. The fuel pump is a mechanical one with a glass bowl on top. There is a filter inside it which is clean. I also haven't pulled this apart though. I assume there are a couple of poppet valves in there and one might be leaking? I'm use to electric pumps so I'm not 100% confident with normal behaviour of these.

Does anyone else have this problem? Is it a common fault with the B18/B20 engines? Or have I missed something?

Thanks.

[PaulWphoto]

I have the same trouble with my 64 1800S. I've fitted recon carbs and tinkered endlessly with the timing, valve clearances etc.. When it runs it runs quite well.

It doesnt seem to like any choke at all.

The starter motor doesnt really turn the engine over that fast and i suspect that at this low speed the fuel pump is not working as well as it does when the engine is running.

i'm afraid i dont have an answer for you but i will follow this thread with interest.

[Ron Kwas]

A;
I have a bit of trouble starting my B18 P1800 first thing in the morning. At all other times its normally right on the ball. I'd call that a start after cold-soak...especially in winter...so you'll need a properly working choke...at "other times", like after a short fuel-stop, it's called a start after hot-soak...no choke then...

I've replaced the plugs/leads/points/condenser/rotor/distributor cap/air filters. Correctly adjusted? Were same symptoms occuring before these replacements?

I removed the single fuel filter as it was full of crud. It was at the back between the fuel tank and solid pipe. I will fit one at the front before the fuel pump when I manage to find the correct sized fuel line. Fufi must be able to flow fuel obviously, but demand at starting is low, so I don't expect this to be causing difficulties. How old is fuel?

I've tuned and balanced the carbs (twin HS6s) and they seem in decent condition. The pistons go up at the same speed, and drop more or less in sync. There is ATF oil in the pots. Not that important at all for starting!

When starting it in the morning it will fire on the first turn but not catch. Then it takes a lot of winding to get it to catch. This first catch will run very very rough and won't come right. If I get to this first catch, turn off the ignition, then restart it will run perfectly. Before making the second starting attempt, feel exhaust pipes at head...try to determine which cylinders are firing, and which not...this may point you to one of the two carbs, or some of the high voltage parts...

I've tried lots of different choke settings when starting, from full off to full on. Doesn’t seem to make much, if any, difference. Is choke action at jets confirmed...not just at control? If working correctly, choke WILL make all the diff for cold starting...See: http://sw-em.com/checkchoke.htm

I haven't pulled the carbs apart yet as I don’t get much time outside work at the moment. One thought is the float chambers leaking fuel out over night. ...easilly checked before any starting attemps, but one would also expect to see drops of fuel...

I also haven’t replaced the coil, but I doubt its that as after this first start everything seems to be good. I aggree here, but remember to keep an open mind when troubleshooting!.

Another thought is the fuel running back from the carbs to the fuel pump, needing a little wind to get back to the carbs.Fuel drops into bowls through their valves...unless it runs uphill, that's not possible...only flowback that is possible is from fupu output line up to carbs (this is indeed downhill), if valve is not sealing well, but I doubt this could cause starting problems...starting occurs from fuel in bowls. This doesn’t explain the weird first catch symptom though. The fuel pump is a mechanical one with a glass bowl on top. There is a filter inside it which is clean. I also haven't pulled this apart though. I assume there are a couple of poppet valves in there and one might be leaking? I'm use to electric pumps so I'm not 100% confident with normal behaviour of these. Mech fupus work just fine...if you install an electircal one, you WILL overflow carbs with too much pressure!

Does anyone else have this problem? Is it a common fault with the B18/B20 engines? NO Or have I missed something? Clearly!

Additional: Misfiring suggests an IGN issue...if you tach works (even if not accurately) what is it indicating during misfirin?

Good Hunting, Cheers from Connecticut!

[brucelee34]

Ron - I have an electric fuel pump and it does not overflow. When the floats are closed the pump stops. You're worrying me by saying that , are you saying it is overflowing when i'm driving?

[Ron Kwas]

BL;

My statement about FuPus was simplified and without explanation or substantiation... so I'll elaborate and summarize what I know: As a rule, the Electric FuPus put out a lot more pressure (and volume) than the bowl valves (which are only acted upon by the minimal force of the float) of SUs are able to hold back...as owners who install them typically find out with some horror as they urinate fuel out the vents and all over the place the first time power is applied...we all know, or have certainly heard of SU bowl valves having trouble holding back the (low) pressure of a mechanical pump if things aren't perfectly clean and filtered (they're just not that strong, additionally they are known for being sensitive to contamination)....so the next thing they do is try to bring that pressure down with a FPReg ...trouble is, and experience has shown, that low pressure regs in that range are notoriously low quality and unreliable, so a working solution using an elec FuPu typically brings with it the need to tinker (a lot!) to get a working setup...and what remains in the back of ones mind after you do get it working is the sight of all that fuel running down the carbs not far the gen as a source of ignition...I wonder just how many Volvos have been torched from the dreaded "external combustion B18 syndrome" because of this...worries like that must be along the lines of having an 18 year old daughter!

OE mechanical FuPus typically only put out about 2-3PSI, and MUST be installed with the spacer to limit excursion of the actuating lever by cam excentric or they will cause the same incontinence as pressure and flowrate increase.

If you have an elec FuPu setup which doesn't leak, great...one can't argue with what works!...and I don't mean to unnecessarily worry you, but I wonder what pump (vibrator or motor type), bowl valves (neoprene cone-in-seat or double ball [Grose-Jet] type), and if you have a FPReg? I believe some elec FuPus have internal regs or provisions (perhaps electrical?) for limiting pressure and flowrate...do you have one of these?...what brand is it?...your turn to eleborate!

You state "When the floats are closed the pump stops" how can this be? are your certain of this...can you tell by the noises it makes...if so, it must sense backpressure and turn itself OFF when valves are closed and there is no demand for fuel...now I am really interested in what type of pump this is!

This subject comes up occasionally on Brickboard as another owner goes through a similar ordeal... If you have a working setup, please tell us about it, this knowledge needs to be shared!

Cheers from Connecticut!

[Derek UK]

"You state "When the floats are closed the pump stops" how can this be? are your certain of this...can you tell by the noises it makes...if so, it must sense backpressure and turn itself OFF when valves are closed and there is no demand for fuel...now I am really interested in what type of pump this is!"

Electric fuel pumps for carbs normally work like this. SU electric pumps have been doing this since the '30s. It's the same principal as a mechanical pump except the back pressure moves a sprung diaphragm which moves an on/off switch. This is different to FI pumps that maintain a constant pressure and return the excess to the tank. There are pumps around that work well on carbed Volvos but most, Facet and the like, need to be fitted next to the tank rather than under the bonnet/hood. These "push" the fuel rather than pull it as is the case with under bonnet "suction" pumps. Huco make a 1.5psi suction pump that works well under the bonnet and Facet make suitable "low" pressure models for use at the back near the tank. Good advice, sales and service from here.(no personal connection other than as a satisfied customer).
http://www.fastroadcars.co.uk/shop/i...iewCat&catId=8
They are on eBay too.

If this car needs "no choke" it may be set too rich. The initial instant start may be due to fuel leaking from the jets into the manifold due to the float levels, one or both, set too high. Correct setting should give a fuel level just below the top of the jet when off choke. It's only about 1mm and that allows the low vacuum at idle to suck the fuel it needs from the jet. (simplification!)

[Andrew (UK)]

The other thing that worries me about electric pumps on a carb car is that I have never heard mention of any device to shut off the pump in the case of a crash. If the line from the pump to the carbs is damaged then the electric pump can quite easily carry on pumping the petrol out of the damaged line which is an enormous fire risk.

[222s]

There were certainly shut-offs on some '70s BL cars (I think they were inertia triggered) as I remember reading a tech article ages ago - I think it was Practical Classics - about how to reset it.

[pookie]

There are two types of electric pumps. High pressure - used on fuel injection systems (typically around 70 psi). These usually have an inertia switch to turn them off in the event of an accident to prevent massive leakage of fuel. There are some competition cars that use these pumps with carburetters because they also deliver high volumes of fuel. However, they are ALWAYS fitted with a fuel pressure regulator ( typically set at around 4psi ) as that kind of pressure would blow the float needle valves off their seats.

Also there are low pressure pumps ( the S.U. electric pump is a classic example ) specifically for use on carbs which run at around 3-4 psi. These have always on production cars been wired directly through the ignition switch.

All carburetters will work fine on a low pressure pump with no fear of flooding. But Andrew is quite correct they can and do leak in the manner he described. The answer is to fit an inertia switch.

Pookie

[asneddon]

Thanks for all the replies!

I didn’t get much time in the weekend (new baby and all that), but I did find that the choke of the front carb doesn’t seem to be set correctly any more. The fast idle cam doesnt actuate the spindle until the choke is past the length of the choke cable. I'm not sure how this happened as it use to work and I wouldn’t have thought setting the mixture a few flats would have made all that much difference. Adjusting this didn’t fix the issue though.

As for being set too rich, it is a little, but that’s on purpose. I don’t care that much about fuel economy and would prefer to over fuel to be safe on the valves. Its not so rich that it would be washing too much oil off the bore. I would say about half a turn rich from perfect.

I tried to feel the exhaust manifold after it failed to start, but as far as I could tell they were all about the same.

The Rev counter is on the back ledge, waiting for a new transformer to see if I can refit it. I would estimate the revs are at about 600 and bouncing up to 1200 when it does its false start.

The cars going into Tony Barretts tomorrow to get a new exhaust fitted, so the carbs will be moved to a new manifold. I will wait to see if this fixes the problems. One of the reasons for the new manifold is because I'm not convinced there isn’t an intermittent air leak in this one. The other is because the current one hits the ground/body too often for my liking. The fumes up from the end of the front pipe are probably not a good thing either!

Allister