1989 Evinrude 40hp- fuel flow problem???

[Bill Collector]

1989 rude 40hp. Motor sat for about 8 years. I've serviced everything that needed to be done on it and it ran like a champ. I've converted the engine to premix. Carbs rebuilt last month and good compression at 128 per cylinder. I've had it out twice with no issues. Yesterday I took it out and it ran fine for about 15 minutes. Then it began starving for fuel. I checked to see if the bulb was firm and it seemed to me it was slightly soft. I pressed in the electric primer while running it and the engine took right off running perfect, but once that fuel burned off it was back starving again. So I know it's a fuel problem. I know it was starving for fuel so I checked the following-<br /><br />1. Tank is half full of gas and the hose is submerged in the tank.<br />2. Vent is open.<br />3. New gas line from tank to engine with bulb. Again bulb was soft<br />4. Pumping the bulb did not help feed the motor more fuel.<br />5. The line from the tank to the engine was not constricted.<br /><br />Question- fuel pump? Where do I go from here?

 

[Bill Collector]

Re: 1989 Evinrude 40hp- fuel flow problem???

Anyone?

 

[Xcusme]

Re: 1989 Evinrude 40hp- fuel flow problem???

Bill,<br />Since the motor did not 'pick-up' when you squeezed the bulb, (this would bypass the fuel pump), points to the carb, not necessarily the fuel pump. You can disconnect the fuel line at the carb, put end of hose in a can and turn the motor over. You should see fuel being pumped into the can. Check fuel line from pump to carb for fuel leaks and or air leaks.<br />Check carb float level, needle seat, and clean low speed idle circuit. Report back on what you find.<br />As a side note, when it's running likes it's starved, pull plug wires, one at a time and note if motor drops RPM's. If removing a plug wire does not make a change in RPM's, you have a dead cylinder.

 

[Mark42]

Re: 1989 Evinrude 40hp- fuel flow problem???

I've converted the engine to premix

How did you convert it? Sure all the plugs are on tight? I would double check this work first, then continue debugging.<br /><br />I would think the electric choke would not work if the pump failed because the choke needs fuel pressure to squirt the gas into the crank case. Is it possable that dirt or water got in and is starving the motor for fuel? Did you try using the choke more than once? If you did and it still worked then the problem may not be the pump. I say that because if the pump failed, the choke would let the pressure off the system, then the next time you used the choke, there would be no gas pressure left. Just a thought.<br /><br />Mark.<br /><br /><br />Why did you convert to pre-mix?

 

[Bill Collector]

Re: 1989 Evinrude 40hp- fuel flow problem???

Thanks guys..My history is maintaining and rebuilding 80's and early 90's stand up model jet skis. On these I would use a block off plate on the oil pump and premix the gas. I once had a ski where the oil pump failed and you know what happens then. So this boat is a 13 foot Wolff, very much like a hydrostream race boat. It has a gas tank in the bow but I filled it with foam and use a removeable 6 gallon tank in the rear. I have pics I can email. <br /><br />I don't believe water got into the fuel or lines. I keep it covered. I pressed the primer a few times and I was humming along at about 40 when doing that. The engine really ran well. I guess carbs is my next dilema.<br /><br />I rebuilt both carbs and it was running like a champ! I'm thinking it's not the carbs because if I hold the hot foot throttle to the floor and hit the primer thing on the key, it shoots gas in and the boat takes off and runs awesome. Once it's burned off, the engine stays running and idles just fine. does the primer shoot gax into to the cylinders or the carbs?<br /><br />I checked for fuel leaks. I guess I'll just have to dig into the carbs again and see what I find. The rebuild on them was complete. <br /><br />PLEASE- any other thoughts are welcome.

 

[Mark42]

Re: 1989 Evinrude 40hp- fuel flow problem???

The primer shoots gas into the crank case, past the carbs. Not sure if before or after the reeds, I'd have to look at the manual, but I beleive its after the reeds.<br /><br />How do the plugs look? Does it look like one or both cylinders are running dry?<br /><br />BTW, the oil pump system on these motors mixes the oil with the gas before distributing the gas to the carbs, so you can't run one cylinder without any oil. Its all or nothing. And the warning system works well. It might be worth connecting it back up just to see if it has an affect or not.

 

[Bill Collector]

Re: 1989 Evinrude 40hp- fuel flow problem???

Thanks for the help fellas...It was a sliced fuel line from the splitter. The one after the fuel pump and before the carbs where it splits the line and feeds both carbs. $2.12 repair.<br /><br />I guess the oil pump preference is a personal thing. I've been pleased with the premix routine. <br /><br />Thanks again

 

[Mark42]

Re: 1989 Evinrude 40hp- fuel flow problem???

Thanks for the update/solution. Will keep this info in my head incase I get similar problems.