Heat Soak

[Marinanut]

I've got an annoyance on the Ital. The problem is I am getting a lot of heat soak back through the carb after a run and I don't know why, nothing appears to have gone AWOL.
It will start on the choke perfect, then settle to an idle, pulls like a train through the gears and after a short stop (ie petrol station) will start fine; BUT if you leave it for 1/2 hr or so it will not start for love nor money. I had the AA out yesterday because we got stuck and the battery got weak from trying - put the battpak on and wallop, away she went. I have replaced the coil (in case of being weak, it was original so it didn't owe me anything...), points, condenser, plug leads, plugs are OK, timing OK but after a run this morning and standing for 30 mins, the top of the air filter was so hot I couldn't put my hand on it or touch the carb. Most peculiar.
Any ideas?

[Number 63]

I left the heatshield off my old 1.3 Ital once after a carb rebuild and it suffered terribly from heat soak issues. But, I'm guessing your heatshield is still very much in place so the only other explanations I could offer are that either it is running very lean and therefore the exhaust is getting very hot or your ignition timing is too far advanced. This is a 1.7 IIRC? I can't remember if that had a water heated inlet or not and if so, I'd check that it's not leaking into the inlet manifold or that the engine is not overheating for other reasons.......

[Marinanut]

I'll re-check the ignition and mix tomorrow; funny thing is the engine doesn't appear to run hot. Hmmm.

[MarinaCoupe]

This has come up a few times recently and I am starting to wonder whether it's actually the latest fuels with ethanol in them evaporating in the fuel float bowls.

I realised the problem, when one time the AA man who came out to me, grabbed a can of Easy Start from his cab and squirted it into the filter inlet mouth, not just a drop but a good 30 seconds worth. The car fired up straight away and then ran OK, because once turning over properly, the mechanical fuel pump had enough suck to draw up fresh fuel.

Last time it happened on mine, I whipped the tops off the HS carbs and both bowls were dry. The mechanical fuel pump didn't have enough suck to pull up fresh fuel whilst the engine was cranking over.

My solution has been to fit an electric fuel pump and it hasn't happened since. I guess the cheap way would be to car a can of Easy Start.

[JubileeNut]

I think when mine gets to hot ticking over I start suffering from that! Or something similar.
But I also noted when I went to my last show that I had lost one of the asbestos pads so now it will be worse. plus it sounds like it is more one carb than the other. Also when left for a couple of weeks it takes a while to crank over to start normally 3rd go and its away. Only crank it few a few seconds at a time.

Also my workshop manual shows a heat shield on the fuel pump as well :shock: I have never seen one fitted.
The 2 bolts are replaced with studs and I guess the spacer is thinner to allow for the metal thickness other wise the pump is moved away from the cam.

[Marinanut]

Had a play today, twiddled both mixture and timing and she now runs better without pinking. Bit of a git to start, but tried the Easy-start once hot and she started and ran no problem. I note that there is a place in the wiring diagram to fit a fuel pump for hot climates, maybe the crap petrol we no have will require this fitting. Getting to the bottom of it, bit by bit (P*ss*ng down with rain doesn't help, either...).
MarinaCoupe, where did you fit the fuel pump on the line and did you leave the mech pump in?

[MarinaCoupe]

I fitted the pump by the tank, just behind the line of the back axle. Initially I left the pump mounted but not in the fuel line. Once I got the electrics and the safety relay fixed, I removed the mechanical fuel pump. The Canadian and some US Marina's were fitted with MGB pumps as standard.

[jiversteve]

Chris, Did you fit a pressure regulator as well as the inertia safety switch? I suppose it depends on the performance of the pump.
Blanking the old pump aperture is easy using a Mgb or a classic Mini plate.
Interesting comments from Paul and reading my Haynes manual. My pump is held on with bolts and is a pain to install. Studs would have made it a lot easier.
I don't think there would be a problem with spacing the pump out another 1/16" to for a home made heat shield. The pump lever is already under tension, and it's the travel of the diaghram that is important for fuel delivery. Studs would be essential as holding three gaskets, spacer, heat shield and pump, then threading a bolt through would be nigh on impossible.

[JubileeNut]

Your right there Steve!
I had trouble getting mine back on after I had a small oil leak:shock:
I was thinking of putting studs in instead.

[MarinaCoupe]

I already had aMalpassi fuel filter and pressure regulator, although it runs wideopen. The key thing is to use a pump with the same pressure range as the SUs - 1-3 psi. The obvious candidate is the SU MGB pump most Facet pumps are for Weber carbs which runs at 3-5 psi. It doesn't sound so different but it would screw up the running of SUs.

I actually use a Fuel Flo pump which I bought a couple of years ago. They come from New Zealand, although I havn't seen them advertised inthe UK for 18 months or so.

I havn't fitted the colision sensor yet, I have rigged a relay that is always on except when the oil pressure light comes on. This means that if the engine stops and the ignition is on, then the power to the fuel pump is disconnected.

[JubileeNut]

Once I got the electrics and the safety relay fixed

Did you fit a pressure regulator as well as the inertia safety switch?

I expect you need all these if it were under great pressure like injection cars but the Moggie had an electric pump and I don't remember it having any safety bits and pieces.
I guess you are fitting them for your piece of mind but are they really needed?
Or are they required under MOT etc?

The SU electric pumps I remember just slowly gave a good fuel supply and they were good as they started before you crank so you know the fuel is up to the carbs before draining the battery!

[locost_bryan]

I actually use a Fuel Flo pump which I bought a couple of years ago. They come from New Zealand, although I havn't seen them advertised inthe UK for 18 months or so.

Fuelflow pumps website here, but no sign of the new improved website due in September 2009.

[MarinaCoupe]

Paul,

Yes you are right, I fitted the relay for peace of mind and will fit the inertia switch for the same reason.

I recall my MGB from the 1970s, you'd switch the ignition on and there would be a ticking noise as the pump filled the carbs, when it stopped then you turned the key to start the car. The thing is if you had a big prang and were say unconcious, the fuel pump stayed on, pumping fuel, not a happy thought.

[Kilroy]

not a happy thought

So don't do that.

You could be struck on the head by a flying piano - but why would you bother having that thought.?

I have zero insurance.
None.

If you buy into the philosophy that something bad is going to happen - its like you are willing it to.
I intend that nothing bad is going on at all.
Thus far - it hasn't.
I don't watch tv and I don't read the newspaper.
Nothing bad is happening in my world at all.
I relate to people on face value - regardless of what ethnicity they are - or what sort of hat they wear.
If they want to talk to me about my Marina - I engage them. I don't look at them and decide they should not be encouraged.

Amazing how liberating it is.

Give it a go.

[Marinanut]

I already had aMalpassi fuel filter and pressure regulator, although it runs wideopen. The key thing is to use a pump with the same pressure range as the SUs - 1-3 psi. The obvious candidate is the SU MGB pump most Facet pumps are for Weber carbs which runs at 3-5 psi. It doesn't sound so different but it would screw up the running of SUs.

According to the book of words the Ital 1.7 needs 6psi minimum feed to the carb. I have bought an adjustible pump 3-7psi so I'll have a play with it when it arrives. I like the idea of using the oil press light to operate a relay.

As an aside, I have done over 100 miles today, laden and unladen and apart from a dodgy connection to the starter solenoid, she's run like a dream (bit of a wet one in this mornings rain.... :shock: )