4CU EFI Module 3.5L Rover V8 1985 Marcos Mantula

I am trying to figure out a problem with restarting the vehicle after the intial start. The suspect vehicle is a 85 Marcos Mantula with a 3.5 Rover V8 using the 4CU electronic module. The car has only 11K miles. The motor runs very strong, breaking loose the tires easily in 1st gear at nearly any rpm when the pedal is floored. Rubber in 3 gears. It starts with a turn of the key just reaching into the window. It idles steady at 650 rpm and has no
hesitation in any gear even when floored in 4th gear
at 25 mph. Everything is great except..... turn it
off, even after running for minutes it won't start for
hours. So it can't be vapor lock, if I push the air
flap the pump runs. If I squirt starting fluid into
the plenum it won't start, i.e. something in the
system prevents the coil from energizing and sending
voltage thru the spark plug wires.
There is no problem with the fuel. Could there be something in the ECU that immediately heats up as I start the car, is basically not involved in the engine run circuit (i.e. only the start circuit) because as I said I can start the car immediately turn it off and it won't restart, no vapor lock since the motor and fuel didn't even get warm.

I quess one of the easier methods to see if it is the
ECU I should fine a local V8 triumph or morgan with
one and ask to let me swap it out.

Any help on this one??

I think that you are already on the right track. An alternative suggestion would be to check with a local Land Rover dealer or an independent specialist, they used this engine and ancillaries on contemporary Rand Rovers, and this may well be a problem that they would have come across in the past.

does the oil pressure sensor enable start on this ecu?

Not sure on that one. I do know that I have a reading when running at the gage and I am pretty sure it is electric. Would there be both a oil pressure transmitter and a oil pressure switch?

i'll have to look on my old range rover prints, but I think oil pressure is required for the fuel pump to work. Usually, though, that goes through a relay. I thought maybe there was also an ignition enable signal through the ECU.

Not getting spark on restart? Do you have a stock amplifier on the side of the distributor? Check and see how hot is is after shutdown on start-up, it is in the side by the thermostat hose leading to the radiator!

try this link for a nice article on the 4cux ecu

https://www.britishv8.org/Articles/Rover-14CUX-EFI.htm

Thanks for the info but I was looking for 4CU not the 14CUX but there was some interesting info there.

I will check and see if the amp is hot.... thanks.

Give Woody a call at the Wedge shop. He knows more about the 3.5 Rover than anyone. He will be the biggest help