High Temp Horn or Not ???

[triclyde]

I have a 1989 Evinrude 150 . I seem to have a problem with the horn going off. I have done some research as too what causes this and have had several mencanic's point in different directions. Here's what I have done so far. <br /> 1.) Replaced the water pump. ( do have a water pressure gauge- holds steady at idle ( 8 lbs. and at WOT 16-18 psi.)<br /> 2.) replaced both thermostats <br /> 3.) replaced the fuel / water separator<br /> 4.) replaced the in-line fuel filter ( inside the cowling)<br /><br /> At first I was told that the engine was HOT , so I took the boat out and ran it until the horn went off ( pulled the cowling and used my digital thermometer and shot temp's all up and down the heads. Temp's ran from 142- 156 at the hottest spot. I could put my hand's on the heads ( while running). I didn't consider them to be excessivly HOT. This seem's to only happen at or above 4000 RPM's At around 3400 RPM's the horn will not go off. I was told that if it was a HEAT problem that the engine would drop off to 3000 RPM's and stay their until it cooled off. This is not the case here. Once the horn sounds I mantain the same RPM's and can even increase. <br /> Could the water deflector's be bad???<br /> Another Mechanic said that I have a fuel restriction?? That too would sound the contuinious horn. Once this horn goes off it take aprox 2 min. stop.<br /><br /> Note: The VRO system has been disconnected and I pre-mix at 50:1<br /> Thanks for anybody's help on this problem

 

[Joe Reeves]

Re: High Temp Horn or Not ???

Dennis..... If the water deflectors were swelled, that would cause the engine powerhead to overheat just as if you had a faulty water pump.<br /><br />Notice just behind the electric starter, near the top of the powerhead, there is a small plastic like component that has a fuel line connected to it which leads down to a tee that is inline with the main fuel line assy. That component also has a tan wire leading to it. The function of this component is to ground out that tan wire if a fuel restriction exists, which is turn activates the continuous warning horn.<br /><br />When the warning horn sounds off, remove the tan wire from that component. If the horn ceases to sound off the moment you remove that wire, you have a fuel restriction. In all probability, if that restriction exists, it is due to a faulty "anti siphon valve". See below.<br /><br />(Fuel Anti Siphon Valve)<br /><br />Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vaccum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.<br /><br />The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting.<br /><br />That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

 

[triclyde]

Re: High Temp Horn or Not ???

Thank's Joe<br /><br /> I'll be checking and trying your advice.<br /> I will be getting back to you

 

[triclyde]

Re: High Temp Horn or Not ???

This is for Joe Reeves,<br /><br /> Joe, I found and removed the " Fuel Anti-Siphon Valve ",( at the tank) replaced it with a brass fitting. This cured my problem, Plus , I taped two Thermocouples to each head ( on top of the thermostat housing ) connected this to my Digital Multimeter. This enabled me to read the temperature of each head during the test run. Both heads didn't exceed 128 deg. I ran the boat (1989 Renken 2008 W/A )at 4400 rpm's ( 32 mph) and at 4800 RPM's ( 37 mph) for 12 miles with NO horns or problems. I would go a few miles then stop and plug in the thermocouplings and do a temp reading, repeated this several times.<br /> <br /> Joe Thank you for your expert advice. You helped me solve a very frustrating problem<br /><br /> Dennis

 

[Joe Reeves]

Re: High Temp Horn or Not ???

All rightly...... Now, just where do I send this bill? (grin). Seriously, always glad to be of help.

 

[Beaux]

Re: High Temp Horn or Not ???

joe- can you leave that anti-siphon valve out permanently? shouldn't he replace it with a new one now that he has solved his problem? Just want to know for knowledge sake....thanks

 

[Joe Reeves]

Re: High Temp Horn or Not ???

Beaux..... The ones that I've dismantled, I've left that way as the entire length of the fuel line in every case was above the top edge of the tank level.... no chance of having a fuel line break and have the fuel siphon down into the bilge.<br /><br />However, if there's any chance that the fuel line would be (at any time) below the fuel level, I'd suggest replacing the fitting with a new anti siphon valve after the problem is solved. For what they cost, it might be a good idea (preventative maintenance) to simply replace the valve every two or three years, or at the first sign of trouble.

 

[Beaux]

Re: High Temp Horn or Not ???

thanks joe.....