Ecu box from 150 in a 240

[rsalvarez]

Hi, i just purchase a jet boat with the 240 engine, is incomplete, ECU box is missing, a friend will lend me a 150 hp box to test the engine, there are 3 ECU boxes for this series A27,A30,A31, i will install a 824003A27, the parts catalog indicate 824003A31,
as i can understand the ecu will work , but there must be the software the difference, i cant find the ecu curves grap to look, my aplication will be as tour boat, never will be over 20 mph, just at planing speed and below on a seadoo 18 ft, max 3000 rpm as tour speed is 5 knots
I am looking for advice, about this box possible risk ,and if can be reprogramed, cant find on ebay
Asi dont need the 240 hp, 150 will be fine if there are no inmediate rist to the engine as i understand the max advance is programmed and fuel injector signals, i guess start up and low speed must be similar.

[XstreamVking]

150 box might actually be better than a HP box as it is usually fairly fat with fuel in the low range.
I'm just guessing with no knowledge of the curves.

[rsalvarez]

150 box might actually be better than a HP box as it is usually fairly fat with fuel in the low range.
I'm just guessing with no knowledge of the curves.

Were i live, any spare part is hard to find, have to be searched on websites, i apreciate your reply as ai just guess that must work as are the same engine fuel management system
Thank you will test this sunday,will premix just in case of lean , some extra spark plugs and temperature monitoring.

[ssv1761982]

If someone would decide to run it hard some day I imagine it will be lean and boom. I don't know how you can guarantee nobody will ever try to go fast.

[rsalvarez]

i was able to locate a 200 off shore EFI control box , i read about brucato programable ECU,Mercury Marine are not interested in support a 20 years old product, they are not Kiekhaefer Marine, they sell and forget, is managed by resellers,is like the dog seller
so the owners has to learn to keep our boats running

If the 240 efi ecu was designed for use on a 18 ft boat, in comparation to a 240 on a 23 ft boat, just by deduction the jet boat ecu must be sending less pulses as we dont need the same fuel to get on plane , same with a 150 or a 200, the ecu replace the low and high speed jets, will send the right fuel at the right time, the engines do not have a load cell to understand, do not connect rpm to speed to know if we have an issue with prop.
ECU just read tpi position ( voltage) sense vacum and ignition, and decide how many pulses will send, on any engine

the question now a 200 off shore will be safe?