Dabbler_E
Petty Officer 1st Class
- Joined
- Apr 20, 2009
- Messages
- 338
Like airline employees, denizens of this forum sometimes see people at their worst: stressed out, frustrated, at wits end. We hear ?I'm almost ready to chuck this @#$% motor? and ?I?ve rebuilt the carb 3 times, how could it possibly be a carb problem?? Yet, these forums have helped untold people solve their problems without them even having to ask -- they just look up what's happened to other people and learn. The knowledge base available here has saved me time & money & heartache on many occasions that I haven't posted about ? so I?m posting this one just to let you all know what a help you've been.
I recently acquired a non-running 1971 Evinrude 25 hp for next to nothing (which I never would even have tried without what I've learned here). It?s taken a fair bit of time and parts to get it back on its feet (coils, condensers, points, spark plugs & wires, water pump, plus head & exhaust cover gaskets b/c the PO took them off), but I?ve got less than $400 in the motor total and got it running fine in the tank. So I put it on my 14? semi V (see resto thread in my signature) and hit the lake. Idled OK, but when I went to WOT it bogged and surged. When I squeezed the bulb, it revved up. ?Aha!,? I thought ?Fuel pump!? Then I looked online and found that the fuel pump for this model is obsolete & tough to find. Couldn?t find a diaphragm kit, just a replacement unit, for about $90 (over $100 at the local marina). ?Blast!,? I thought.
Then, I checked this forum and searched on ?Surging? and got lots of info, mostly related to the fuel pump, but one thing that kept coming up was ?air leaks in the fuel line? So, I ran a line from the output of the fuel pump into a jar and cranked the motor. It pumped just fine, but bubbles kept coming out, long after the line from the pump to the jar should have been purged. Before, when I had run it on the tank (not on the boat) I had run a line straight from a gas can to the motor. Now, when I ran the motor in a tank (about 2500 rpm) using the boat?s fuel lines, it would run out of fuel after about 1-2 min (unless inhaled exhaust kept the rpms down). ?Aha!,? I thought.
So, I went about things systematically ? first, go back to last good condition. Hook up line straight from gas can to fuel pump inlet ? still OK. Then, attach a quick-disconnect to the line from the gas can, and run fuel through the fitting & lines on the motor ? OK. Then, detach line from water-separating filter and test fuel line downstream from there ? OK. Then, include the water-sep filter ? OK (I confess that I had suspected that filter, but my suspicions were unfounded). At this point, I thought ? well, maybe I?ve solved the problem by removing and reattaching hose clamps. So, I went back to the original set up (with tank vent wide open and tank full of fuel) and sure enough, motor out of fuel coughed & died after 2 minutes. Pumped up the bulb again and tried again ? still died after 2 min. ?Aha!,? I thought ? the problem is between the filter and the tank. And, ultimately, it was the line between the tank and the filter. I don?t know exactly where the air leak was, but replacing that line fixed the problem.
I tip my hat to the Iboats JonnyRude forum for saving me nearly $100 on a completely unnecessary part and putting me on the path to a successful diagnosis, and a much happier motor.
THANKS
I recently acquired a non-running 1971 Evinrude 25 hp for next to nothing (which I never would even have tried without what I've learned here). It?s taken a fair bit of time and parts to get it back on its feet (coils, condensers, points, spark plugs & wires, water pump, plus head & exhaust cover gaskets b/c the PO took them off), but I?ve got less than $400 in the motor total and got it running fine in the tank. So I put it on my 14? semi V (see resto thread in my signature) and hit the lake. Idled OK, but when I went to WOT it bogged and surged. When I squeezed the bulb, it revved up. ?Aha!,? I thought ?Fuel pump!? Then I looked online and found that the fuel pump for this model is obsolete & tough to find. Couldn?t find a diaphragm kit, just a replacement unit, for about $90 (over $100 at the local marina). ?Blast!,? I thought.
Then, I checked this forum and searched on ?Surging? and got lots of info, mostly related to the fuel pump, but one thing that kept coming up was ?air leaks in the fuel line? So, I ran a line from the output of the fuel pump into a jar and cranked the motor. It pumped just fine, but bubbles kept coming out, long after the line from the pump to the jar should have been purged. Before, when I had run it on the tank (not on the boat) I had run a line straight from a gas can to the motor. Now, when I ran the motor in a tank (about 2500 rpm) using the boat?s fuel lines, it would run out of fuel after about 1-2 min (unless inhaled exhaust kept the rpms down). ?Aha!,? I thought.
So, I went about things systematically ? first, go back to last good condition. Hook up line straight from gas can to fuel pump inlet ? still OK. Then, attach a quick-disconnect to the line from the gas can, and run fuel through the fitting & lines on the motor ? OK. Then, detach line from water-separating filter and test fuel line downstream from there ? OK. Then, include the water-sep filter ? OK (I confess that I had suspected that filter, but my suspicions were unfounded). At this point, I thought ? well, maybe I?ve solved the problem by removing and reattaching hose clamps. So, I went back to the original set up (with tank vent wide open and tank full of fuel) and sure enough, motor out of fuel coughed & died after 2 minutes. Pumped up the bulb again and tried again ? still died after 2 min. ?Aha!,? I thought ? the problem is between the filter and the tank. And, ultimately, it was the line between the tank and the filter. I don?t know exactly where the air leak was, but replacing that line fixed the problem.
I tip my hat to the Iboats JonnyRude forum for saving me nearly $100 on a completely unnecessary part and putting me on the path to a successful diagnosis, and a much happier motor.
THANKS