Hello, I have to do something like a annual MOT for my 2.25L petrol this week, and have one issue that might show up depending on how hot it is the day of the inspection. (I am going to try and go early morning)

The issue is the engine cuts out when it gets hot, if I rev up, or accelerate then the engine cuts out completely to a barely idle (if that). Sometimes if I pump the accel I can get past it with out it dying. I have fitted a electronic fuel pump in series/line (on top of the fuel tank), and it is manually controlled by a momentary switch if I need to overcome a vapor-lock hot start. I think the carb is running out of fuel because maybe the fuel in the bowl is being boiled off from heat to fast. Would I need to change the float level to allow more fuel in the bowl to remedy this? Do I have the incorrect spacer between the carb and manifold, or the something wrong between the intake and exhaust manifold allowing to much heat transfer? Anyone else have similar issues? I don't feel like troubleshooting it for a day or two. This Landy has a quota of only so much work hours, or money put into it every year :lol:.

For me this is not a new issue, but as the weather gets hotter it always shows up. I would like to resolve the issue at the source. Its happens mainly when at red lights, slow city driving, or idling for long stretch.

Timing, petrol, tappets, plugs are all in good shape and the carb had the zenith warp, but has been lapped and seems to be working ok. The fuel line is routed according to the pictures/manual - around the front of the engine to the carb.
I need your wisdom!

My 69 2a had a hot spot flap in the manifold to assist with warm up and if you have one stuck in the "heat" position it would give the symptoms described.From what I can remember there was a weight on the outside of the manifold that moved with the flap,cheers.

Search "vapour lock" I ****ed around with new fuel pumps and people telling me my coil etc were over hearing for months. In the end I got it down to the ethanol in modern fuels blocking the action of the mechanical pump - vapour gets stuck in the valves at the top and the pump stops working. The mech pump on landys is bolted straight to the block with no insulator and so gets too hot for ethanol which boils off at a fairly low temperature.

My motor used to be fine until I stopped at traffic lights or to fill up then the air stops moving past the bottom of the engine and the heat gets into the pump, next time you put your foot down it drains the carb then cuts out - just as you're pulling out in front of a 40 ton truck...

I've now got a facet electronic fuel pump and not had a single problem since. I tried a cheapo copy off ebay first but that was a false economy as it packed in after a couple of weeks.

I've attached mine next to the tank on a bracket and completely bypassed the old pump and fitted a blanking plate on the block.

I also fitted a relay which cuts the pump if the oil pressure drops and there is a "prime" button in the cab that you have to press before starting - a bit belt and braces but should cut the fuel if I roll it. Let me know if you'd like wiring details.

I don't like fitting non-standard stuff but in this case it tried to kill me about 20 times and I gave up after buying 3 new pumps, 2 new distributors and a load of new coils.

ah vapor lock at the mechanical fuel pump! I can try to play with that. I will look around for some hose clamps and then try bypass the mechanical pump. I will change the momentary switch to a non-momentary it goes to a relay so maybe a wire from ignition to electric fuel pump relay.

I hear you about close calls. Mine loves to surprise me all the time, and give me a 3 seconds or less notice to pull off the road to rest. lol

It sure seems to be no fuel, the engine doesn't hesitate it just stalls and sputters a bit (like dieseling).

If you are correct I would like to see your wiring diagram. I have a el-cheapo electric pump installed now, but might switch that to faucet brand if your wisdom fixes my problem. Is your faucet brand pump quiet? Do you remember the model number?

That is a good idea with the oil dummy light. The only thing I can come up with was: and, nor, or, -logic gates.

I will post back in a couple of days and post the result.

Here's the diagram - the idea is that if you roll over the oil light will come on and turn on the relay which will cut the fuel pump.

You say you've already got an electric fuel pump and a mech pump - why both?

The other thing to check is that whoever fitted your carb didn't miss out the plastic insulator between the carb and manifold - I've seen them missing on a few motors.

D

Procrastinated until the sticker experation today. I planned to make a wire from the ac clutch to the fuel pump relay nearby (after market ac kit installed from po's mechanic). Well I found out a rat chomped through a bunch of wires (i guess thats why the A/C stoped working a while back lol), spent all day fixing it, and then trying to solve why the engine cuts out. Still made it to the goverment shop for new stickers and inspection.

To make my story short- after I wired the electric fuel pump to be always on (turn on the AC ) instead of the momentary push button in cab - I still had the same problem as described above. This is with both electric and mechanical in series running together. I then had a look inside the carb to clean it out and BINGO. The float measured I think about 28 mm, as I was bending it to bring it back to 33mm I thought it felt heavy. On closer inspection of the nylon/plastic float it was half full of petrol. Its a fairly new carb. I had a spare and swapped it out, and now my issue is mostly solved. I drove home with the ac off. I still want to do what dominic did and get a proper electric fuel pump that puts out the same psi as the mechanical pump, remove mechanical pump, blank off the mechanical pump port and never look back. To answer your question - I have been using my electric fuel pump to fill up the carb, and for hot starts that I suspect is vapor lock. I have wore out a couple starters lately. My current pump is a china/no name and no specs included brand. I get worried it might be to strong and send petrol out of the carb somehow onto the hot manifold.


Do you think the ethanol blend could cause the float to leak? I could not get the petrol that was inside the float to seep out no matter which way I held it. wierd.

I put one of these just before the carb Sytec Pro Flow Fuel Pressure Regulator | Demon Tweeks

There are cheaper options but I had this on the shelf anyway.

The worry with having the two pumps in series is that if there is a tear in the diaphragm of the mech pump you'll fill the sump of your engine with petrol which won't do it any good.

A/C in a series -luxury!