motor trouble-need help!

[hoggerhead]

I have a 1987 30hp 2 stroke evenrude. got on the lake this morning and the motor cranked fine and i ran it full throttle down river for about ten minutes, then it just bogged down on me. it would idle fine but if you gave it gas it would act like it wanted to speed up, but then it would bog down again. It did that for five minutes or so then picked back up and ran fine for the next two hours. went to leave and it did it again but would not fix its self this time. i set the gaps in some new plugs and put them in. i also checked the screen on the fuel pump it was clean. put the boat back in the water and still no luck! does anyone know what might be causing this??

 

[dtw2]

Check to see if your motor has a fuel filter some where.

 

[hoggerhead]

it doesnt have one, all ready checked.

 

[Bubbakat]

Try pumping the primer bulb while trying to accelerate it. check all you connections from the tank to the motor and also check the pick up tube that is down inside the tank they have a little mesh screen on it and it does clog up at times.


There isn't really too much involving fuel pump troubleshooting, and I'm rather amazed at how many fuel pump kits that are sold in a years time, as standard outboard fuel pumps don't really act up that much in my experience of 20-some years of wrenching. If you feel though the fuel pump is your problem, read on.

A standard outboard fuel pump is a simple device that operates off the pulse of an engines cylinder. A basic rubber fuel line connects the fuel pump to a pulse valve (some models of fuel pump attach directly to the block with a gasket, sealing pulse passage to cylinder), which is normally threaded into the block with provisions of a clear passage to a specified cylinder. The up and down stroke of the piston in the specific cylinder is what causes the fuel pump diaphragm to flutter, resulting in pumping fuel from tank to carbs.

So how do I know the fuel pump is doing what it is suppose to?
As described above, the fuel pump requires an adequate pulse from the cylinder that it is attached to, so first thing is to make sure compression on that cylinder is up to snuff or the fuel pump can't do it's job. If compression checks out, then next thing is to check fuel pump pressure. All non fuel injected outboard motors operate with a fuel pump pressure of about 5 to 7 psi. If consideribly less than 5 to 7 psi exists between fuel pump and carb/s, the motor is likely to be starving for fuel causing idle and/or upper rpm operation to suffer, not to mention a dangerously lean condition.

So what if everything to do with pulse supply to the pump is good, but I still suspect the pump has a problem?
Although I mentioned not experiencing many fuel pumps actually being bad, it is indeed possible for either the diaphragm, check valves, or other problem to develop in a fuel pump. If it's plainly worn out, then so be it, install a kit or replace pump entirely, but I would suggest checking all other things in this troubleshooter page before just taking it for granted your time and money spent on a fuel pump kit or replacement pump will solve your motor's woes.

Could anything else cause the fuel pump to not provide adequate fuel supply to the motor?
The answer is yes. There could be a restriction or loose connection from tank to fuel pump, amongst other things. Assuming you have no leaks (including pinholes in hoses) anywhere in-between, the following would be things to check for:
Fuel tank internal pickup tube clogged, broken off, or otherwise defective.
Anti syphon valve located on tank (is so equipped) could be defective (check ball/spring).
Any kinked hoses between tank and pump.
Defective in-line squeeze bulb (usually the internal check valve).
Defective or incorrectly attached fuel line connectors.
Clogged fuel filter.
Inadequate fuel tank vent or kinked vent hose.

 

[hoggerhead]

tried pumping the bulb while accelerating with no luck. just checked the screen on the pickup tube, and it was clean. its getting fuel from the tank to the motor no problem. could it possibly have some thing to do with the choak?

 

[hoggerhead]

im gonna change the fuel lines tommorow because i did notice a little bit of wetness and the smell of gas underneath the carb. but its been like that every since i bought the boat almost two months ago.???

 

[Breeze]

ya might try puttin some stabils in the fuel.I have had that prob with my lawn mower.never could get it on plainemoScratch .maybe water in fuel.never hurts to use that stuff.good luch

 

[Bubbakat]

It could be water in the fuel but what I would recommend for that is sea foam. Never use automotive fuel treatments in outboard motors. They have alcohol in them and will wash all the oil off the working parts inside it.
Now as for stabill it is safe to use in an outboard as a fuel stabilizer but it has no cleaning properties as for carbon and varnish.
I use nothing in mine but sea foam. it is the best thing next to a 30# cat loading up a rod.


You might want to do a spark test and a compression check to be on the safe side and if you ahve doubts we can ohm the coils.
Pull your plugs and tell me what they look like. Blac oily wet dry or got water on them , light brown or whatever.

 

[hoggerhead]

the plugs i pulled were put in about a week before i bought the boat. they were black and oily wet when i replaced them today. thanks for the help, i really appreciate it!

 

[NRG]

Sounds like gummed up carb, if its been sitting with old gas in it for more than a month is prob gummed up, you prob will need to rebuild it, if it only has one carb pretty easy if more than one a real pain getting carbs linked and synced back up

 

[hoggerhead]

i think im gonna have to take it to the shop because i dont want to get in to something i havent had much experience with. this is my first boat, and i could probably chase this problem around for days, even weeks! thanks for all you guys help.

 

[fish]

Bubbakat is a boat motor guru, I have known him a long time and he really knows his stuff, he has pulled my fanny out of the fire a bunch of times with my boat.

 

[Gunny]

Bubbakat,

First time I ever heard of sea foam.

What is it and where can I find/buy it? How do you use it (just add to gas tank)?

Thanks

 

[Bubbakat]

You can get Seafoam at some wal marts and at auto zone and Oreily's auto parts stores. The directions are on the can but I always fudge a little and use a little more. It is oil based and is good on any motor outboards included. It is the best thing to decarb with that I have found.
If you want a formula to decarb just say the word and I'll write it up and post it for yea.

I also use it in my mowers and weed eaters and my truck. I even pour some in my wife's tea to try to smooth some of those wrinkles out.emoLaugh

 

[hoggerhead]

lolemoLaugh ! i was going to take it to the motor doc, but he was covered up for 3 weeks. i ended up taking it down to the boat guy in soddy, i should know what the problem is before next week. he said from what it sounds like the carb needs cleaned and ajusted?? i will let you know what he said when i find out. im gonna try that sea foam your talking about.thanks again

 

[fish]

The Sea Foam does make a difference, I use it in my tank all the time, it is some good stuff.

 

[hoggerhead]

i got the prognoses on my motor and they said the needle valve on the carb had a peice of rubber missing that is supposes to keep it from moving while in use.thats why it was bogging down. my choke was not working and the carb needed adjusting.so i guess with all being said and done, it was a good idea to take it to the shop.