fuel primer pump /solenoids testing

[adman]

1990 225ETXD: Fuel primer pump for cold starting seems to have stopped working. If engine is given shot of ether, it starts right up and runs perfectly and will re-start easily during course of that outing/day.
No fuel squirts out 3 holes w/hoses off top of unit when cranking engine. With red lever/switch up on front of unit (manual primer?) and cranked engine, fuel squirts out and engine starts when hoses reattached (and chokes off normally until lever pushed down).
I suspect electrical leads (purple, purple/wh & yellow) to unit but how to test/trace these? None show power when cranking engine? Is one of these a ground? Anyone with any advice on this?
Thanks in advance,
Adman

[gander]

My Clymer book does not cover your engine but it does give a good troubleshooting guide for the primer system on my 2000 90HP. Try to find a manual for your engine. It will probably have a step by step troubleshooting guide. You might also check your primer bulb. It needs to pump up hard for your engine to be properly primed. Hope this helps.

[boats.net]

Yes that system works a little different what it does is when you turn the ign key it supply's voltage through the yellow wires, then the engine cranks over and the thermosensor have an open circuit(cold engine) then the ECU(computer) grouds the purple wires to primestart solenoids and activates primestart. Confusing huh? The biggest problem we had with this was the ground wires, check all ground wires on eng and ECU, If none of primer are working then it probably bad ground, key on power, thermosensor or bad ECU.

[adman]

Thanks for your help. If I understood correctly, when I crank engine, unplugged yellow bullet leads to 2 sensors in prime start unit should show power on grounded test light, right? If not, I should trace yellow wire back to main plug connector from ignition and up to ignition switch itself. If there is power in yellow when cranking, then problem is with ground side (purple leads) and I check all engine grounds first, then thermosensors (where are these located?), then to ECU itself. If I get ground and have power and prime start still doesn't work, problem is with solenoid or prime start unit itself, right? Just trying to understand proper order for resolving issue. Thanks again for your patience and knowledgeable advice.
Adman

[boats.net]

Yes you dont have to crank engine, just turn key on to get power to yellow wires, the thermosensor(6R5-85790-00-00) is on the starboard cyl. head, with wire disconnected the primers should activate when cranking, with jumper wire across the leads going to ECU the primers will shut off.

[adman]

thanks again. Will try it out today and see if I can get this resolved. Will let you know how it turns out.