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Stalling / Fuel Starved Honda 75 4Stroke

W

wrg

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[h=2]I have a 2002 honda 75 4 stroke that seems to be starving for fuel. I just put it in several weeks ago and it was running fine. Any tips or guidance would be great.[/h]

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ISSUES
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yesterday, I had a lot of trouble getting started. Then, once it was running it stalled when I put into gear. I found that I could put it in to gear slowly and go to full throttle but even at full throttle I don't believe it was at top speed.

In addition,
- primer bulb not staying firm.
- when in gear there is some subtle speed thrust/reving at all speeds.
- when I do give it has and get the speed up their is an in consistent noise that sounds like an air blast or pop (not to loud but noticeable and concerning. sounds like "Psssh")

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HISTORY
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- I had a carb issue last year, but had that taken care of (these symptoms feel and sound different.)..
- I did store the boat with full tank of gas and stabilizer over the winter


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STEPS TAKEN
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- replaced in line fuel filter (looked pretty dank)
- checked for water in racor (looked fine) - going to replace just in case

Again any guidance would be great. Also a friend mentioned using sea foam.. any thoughts?

Thank
Bill​
 
First - Drain all the gas and put it in your truck or car, then start off with absolutely fresh gas. Run a concentrated mixture of Sea Foam through it to clean out and break up the gunk left by the old fuel.
 
Many thanks Chawk_man

I will try that. ..

So, once I drain the existing gas, what would be an appropriate concentration and amount to run through, or does it vary? I read 1 oz to 1 gallon for seafoam. That said would a 5 gallon batch be sufficient in your opinion?

much appreciated.
 
The following assumes you are pretty convinced you have a carb problem. It could be omething else, like a failing fuel pump, or air getting sucked into the fuel line. I would attempt to eliminate those issues first.

There are several approaches to using Sea Foam. Since you have a carbed engine, initially I would simply spray some Sea Foam into the carbs while engine is running - use a tank or trash can, not the muffs. Start engine, get to normal operating temperature, bring up the rev's to about 1000, spray in straight SF. Stop engine and let it sit for about 15 minutes, repeat two more times, or so.

If that does not help, consider a full decarbonization Get a 2 to 5 gallon fuel container and attach a hose that you can quickly connect to your engine. Mix 1 can of Sea Foam to one gallon of fuel. (You will see all kinds of mixture ratios on the Internet. I know this one workson old two-stroke outboards. Never tried it on a 4-stroke.) Use at least two gallons of fuel. Start engine on normal fuel feed and get to normal operating temperature. Turn it off and switch over to the fuel-SF mixture, restart. Take RPM's to about 1000. After it has sucked in about half of the mixture, turn it off and let it sit for 15-20 minutes. Restart and suck in the rest of the rest of the mixture. Let it sit another 15 - 20 minutes. Don't be alarmed if you see a bunch of black smoke and soot coming out of the exhaust - it's doing it's job. Hook up your regular fuel line, restart and run until you are sure all of the mixture has been burned out of your fuel system. Then change the oil.

If that does not fix the problem, I suspect you are back to a very detailed carb cleaning.
 
again thank you for you time on this.

so I took it out yesterday and attached a second tank. used about 3 gallons for one can of seafoam. There was some improvement but not really enough. Still wasn't hitting my top speed or RPMS.

BUT

I checked the spark plugs and all of them were pretty junked. One in particular may even be in effective. Thinking this may be the culprit...

will report back after I switch them out...
 

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Yep - that's pretty junky. But you need to determine why they have carboned up so badly. Could be just worn out plugs, but check your thermostat(s). That excess carbon could be caused by running the engine too cold, caused by a thermostat that is stuck open. Or, it could still be maladjusted carbs.

Glad you could get out. It's so damn windy here on the Chesapeake, that pleasure boating or fishing is out of the question. Bummer.
 
Do all your plugs look the same? Could be the Sea Foam treatment.

Make sure your plugs are NGK DR7EA.

Make sure your oil is 1/4" below the full mark.

If your boat is just out from being stored....check for any critter nests in the intake muffler (black plastic piece on the front of the engine).

Make sure your choke is not stick open. Make sure the manual choke is not pulled out on the front of the engine.

If changing the plugs does not help, run the engine on a hose at idle and pull the spark plug wires off of the spark plugs one at a time (with an insulated pliers). The engine should run worse when you pull each one off. You just have to do it for a couple of seconds to see if there is any effect. Then, put the plug wire cap just over the plug so you can hear the ticking of the spark.

If you hear spark ....you have spark. If the engine drops in rpm, that cylinder is firing. If there is no drop in rpm, then you found the cylinder that has an issue.

Generally, if the motor ran ok when you put it away....and it doesn't run well in the Spring, then it is normally....what chawkman said, fuel issues, critter issues, or something affected by moisture. If it were a fuel injected engine, it might also be a battery issue.

Mike
 
Thanks Mike,

I actually really think its was this one particular cylinder (4th - closest to the bottom). I just question how the electrode could be bent and what would cause that. These pics illustrate the problem a bit better and worry me more. I am going to take a run in a bit with new plugs and see what happens...

thx again guys

photo 2.jpgphoto 3.jpg
 
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