1990 225 ETXD: Prime Start

[Adman5]

1990 225ETXD: Fuel primer pump (on top carb) 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. <br />No fuel squirts out 3 holes w/hoses off top of unit when cranking engine. With red lever/switch up on front of primer unit (manual primer?) and cranked engine, fuel squirts out and engine starts when hoses reattached (and chokes off normally until lever pushed down). <br />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? <br />Thanks in advance,<br />Adman

 

[FHARVELL]

Re: 1990 225 ETXD: Prime Start

Is this Suzuki or Yamaha? and does it have three carbs or six?

 

[Adman5]

Re: 1990 225 ETXD: Prime Start

Sorry, it is Yamaha and has 3 carbs. Primer pump assembly attached to top carb on port side of engine(facing forward). 2 electromagnetic solenoids (marked A and B) with bullet connectors to purple and yellow on one and purple/white and yellow on other. Purples appear to go into PowerPack box and yellows join and go to main plug connector in front of engine. Is there way to test the primer pump solenoids by applying power and then to test backwards along wires to find out where problem is if the pump tests ok?<br /><br />thanks again, <br />adman

 

[rodbolt]

Re: 1990 225 ETXD: Prime Start

dont play with it much .<br /> remove the upper "fuel" pump and check the diaphram. usually a bad diaphram cauases that problem.<br /> but I will try to remember exactly how that system works. big thing is the TPS must be in the nuteural voltage range. but if ya gotta test remember that on that system one side has 12V and when the circuit is activated the computer completes the ground path.

 

[Adman5]

Re: 1990 225 ETXD: Prime Start

Will test it today and get back to you. Thanks for your help.

 

[onoahimahi]

Re: 1990 225 ETXD: Prime Start

Six years late for the original poster but I've been checking this out on my 1990 Yamaha 225HP and his problem was that the yellow wire should have shown 12 volts as soon as you turned the key on. I've been messing with mine and concluded that it is working and my problem was that I wasn't starting the engine properly (and it needed a tune up.) I was giving it some gas (throttle about 10 degrees forward) when trying to start it and I think that was defeating the prime start mechanism. I haven't found this described anywhere but I think I figured it out. When starting, the throttle plate is acting like a choke as the gas is injected behind the plates by the prime start circuit. By giving it gas, I was opening the throttle plates and reducing the "choke" effect. It's funny that my dash has a choke switch that I have been using for the 4-years I have owned this boat without knowing that it wasn't even connected to anything. Apparently Yamaha didn't inform Wellcraft that this engine doesn't use a choke switch.

The amount of gas injected depends on the engine temperature which is sensed by a thermal resister located on the starboard side near the bottom spark plug. It has two black wires on it. I checked the resistance and it agreed with the manual - 2K ohms at about 80 degrees F and 1K ohm when hot. It wasn't obvious that the prime start was doing anything until I tried to start it with the resister unplugged. Doing that tells the computer that the temperature is extremely cold. When I did that, it was very clear that the prime start circuit was working as engine started right up and ran like a over choked engine at around 1000 RPM or so. Then I plugged it back in and the RPM immediately dropped to 700 and ran smoothly.

Hope this helps somebody - it would have helped me if I found it 4 years ago...

-Scott

 

[Awrey]

Re: 1990 225 ETXD: Prime Start

onoahimahi,
Excellent description of your "problem" Which causes me to ask if you have any knowledge of my "problem." I believe I have a prime start engine (1996 P60 TLHU) as well. And that the electrothermal valve controls the gas to the middle carb to choke it for "cold" starts. My ignition key is able to be pushed in. The guy I bought it from told me to push it in when starting cold to choke the motor. But I dont think it does anything. Like it is for the electric choke I had on my first car. The guy I bought it from was wrong about other "features" on this motor, so I imagine he was wrong about this. Do you have any idea?????