My 1999 Evenrude 40hp 4 Stroke is starving for gas????

[Ethanlooy]

My 1999 Evenrude 40hp 4 stroke wont run right. I know that I should have taken out all the two year old gas that I had stabilized but I thought maybe it would be ok.. it ran good on the maden voyage this year for about 30 min until it started bogging down bintermediately and eventually forcing me to bring it to an idle or it would stall on its own. Then it started getting progressively worse as I limped my way to the boat launch. If shut off or stalled, it will start right up and run fine for 10 seconds but now even if I dont or I do give it gas it will eventually start choking randomly and sparatically until I shut it off for fear it will hurt itself. I tried adding sea foam and 3 times more fresh gas than it had in it. Still the same and getting worse. Went home. Ive replaced the high pressure fuel pump and cleaned out that reservoir, changed both filters, checked the fuel pump... the diaphrams look good. Tried running a new gas line from fuel pump directly into fresh tank of gas, no change. Checked all fuel injectors, tried to soak them for a bit in carb cleaner and tapped some power to them while in the carb cleaner to have them open. Running out of ideas.. gonna try replaceing every one of the fuel lines in the engine next in case the old fuel I had contained Ethanol. Any ideas guys?

 

[jakedaawg]

Change spark plugs. Even if they "look" fine.

 

[jakedaawg]

Also, 3 gallons good fuel added to 1 gallon bad fuel = 4 gallons bad fuel. Take a sample in a clear jar out of the motor end of hose. Wait 15 minutes. What do you see? But I still would say spark plugs on this. Classic issue.

 

[Ethanlooy]

I will replace Spark plugs and replace old gas.. thanks

 

[daselbee]

If you use ethanol fuel, and let it sit for 2 years, then no doubt your HP fuel pump is either trashed, or is seriously insufficient.
Measure the fuel pressure at the fuel rail. Should be about 40 psi. If not, HP fuel pump. Unlikely it is the regulator, but that is a remote possibility too.

 

[Ethanlooy]

That’s what we were trying to avoid replacing because it’s $360! Haha but we did end up replacing the high pressure pump and it’s still doing the same thing... we did test the old one though and found it to be weak in power so I think it was on the edge. We did not replace the regulator.. screw was stripped.. hope it’s not that but after I test a few other things Jakedaawg suggested I may just have to replace that.

 

[Ethanlooy]

Well Jakedaawg, you were absolutely right. After putting hundreds of dollars into it, it ended up being a few dollars worth of spark plugs! I never would have guessed that but I suppose that makes sense when the bad fuel most likely compromised the spark plugs and then the engine was getting too much gas and flooding.. that would produce the same effect on the engine as if it was running out of gas. I tested the gas like you said but I didn’t see any abnormalities... probably because I deluded it with fresh gas and seafoam but I’m going to replace the gas in the tank just in case.. thanks for all the help guys!