Fuel / Hot alarm 150 HP EXEOM

[w2much]

The good part first. Since I have owned this motor I have gone offshore many times over the last two years. Except for a recent power pack problem since fixed it has been great to me.Starts right up runs all day long from trolling to higher Rpms , WOT once in a while just to do it. Usually I run at about 3500- 4000 RPM . My issue is that the fuel restriction / hot alarm comes on only when I first start the motor after idling for a few minutes at the dock. I shut her down then start up and move through the harbor at about 900 RPM then the alarm may sound again. Shut her down starts right up and get going again , a few minutes later the alarm may sound again. Sometimes the primer bulb is hard sometimes a bit soft. I have even let the alarm sound, pumped the bulb with out shutting her down and the alarm will stop. This may recur a few times but will stop for good as I leave the harbor and throttle up. It will not recur all day long , will run like a champ, start fine every time. When returning hours later and coming back through the harbor at the same low speed the alarm will not sound again. As a matter of fact it will not sound again until next time out which is usually the next weekend. It is not getting hot as I can keep my hand on the head and installed a new water pump last year. I doubt if there is an air leak because it runs great all day, even at continuous high RPM. I have on seperate occassions removed the anti syphon valve , installed new fuel lines, new primer bulb, new fuel water seperator, even tried an external tank . The same thing still happens with the alarm. On a few trips the alarm did not sound at all and all was well. I don't think the problem is the VRO pump itself because the symptoms are only at slow speed when I first start up. I have a manual but no vacuum tester. Can a pulse limiter do this? I willl pull and clean mine this weekend. That vacuum switch is about 100 bucks. Won't replace that till I can have it tested but I need a vacuum tester to do so. Any suggestions besides go buy the tester. Appreciate your replies. Thanks

 

[SparkieBoat]

Re: Fuel / Hot alarm 150 HP EXEOM

I assume you have a new/good water pump impeller. a worn impeller can cause slight overheating at low RPMs..also you may consider new thermostats, you could try premixing your fuel for a few trips and unplugging the VRO wires and capping off the oil line. this may help isolate your problem. make sure that you have premixed fuel all the way to your carbs before disconnecting your vro, this could take 5 mins or more with the engine indling, I would run it at least 10 mins to make sure, it will not hurt to over oil for a little while. I would defiantly find out why it is doing this.

 

[ezeke]

Re: Fuel / Hot alarm 150 HP EXEOM

If your engine is not overheating, it is most likely that a constant alarm is from the vacuum switch that tells you that there is a fuel obstruction; that applies to the incoming gasoline line.

Often there is a problem with redundant fuel filters placing too much restriction on the flow of fuel when all other possible causes have been eliminated.

 

[w2much]

Re: Fuel / Hot alarm 150 HP EXEOM

Why only at slow speed or idle?. Not getting hot, can keep my hand on the heads, pumps water, strong pee stream .

 

[SparkieBoat]

Re: Fuel / Hot alarm 150 HP EXEOM

could be a short, or bad overheat sender. only way to find out is to disconnect different alarm wires until you figure out what is causing the alarm. Try unplugging the over heat sender at the engine when alarm sounds if it stops theres your bugger....if not there may be a short, if your tan wire has a bad place in it, could be shorting out somewhere.