Seafoam usage

starkyb

Petty Officer 1st Class
Joined
Apr 21, 2007
Messages
217
My 9.8 mercury is still not pumping gas properly. The compression is 120 on both cylinders, I put a new pump kit (gaskets and new diaphram), new bulb and hoses, new pulsator line and new plugs late last year. The first time I ran it this year it was a few weeks ago with last years gas that had seafoam in it and it ran perfectly. A week later on my way to the lake I put 3 gallons of new gas and oil to the can that had 3 gallons in it already and it hasnt run right ever since. I am afraid to use seafoam because a mechanic said it can ruin my diaphram. And is it possible that there is an obsruction between the fuel pump and carb. Also if the two check valves go bad in the fuel pump would it cause it not to pump gas through the motor, and how can I tell if they are bad. I am running out of things to try. Please help!!!!!!!!!!!!!!!
 

studlymandingo

Commander
Joined
Mar 22, 2006
Messages
2,716
Re: Seafoam usage

The seafoam won't hurt the diaphragm. Could be that last year's gas has clogged up the carburetor. May be time for a tear-down and cleaning.
 

Harker

Chief Petty Officer
Joined
Sep 21, 2003
Messages
452
Re: Seafoam usage

What year is it? Does it have the fuel pump seperate from the carb or is it built into the carb?
 

starkyb

Petty Officer 1st Class
Joined
Apr 21, 2007
Messages
217
Re: Seafoam usage

It is a 1972, and the diaphram is on the top.
 

Plainsman

Rear Admiral
Joined
Apr 2, 2006
Messages
4,062
Re: Seafoam usage

What does "not run right" mean? Year and hp of motor might help others help you as well.

Seafoam will not hurt your engine or fuel system.

And Welcome to iboats!
 

starkyb

Petty Officer 1st Class
Joined
Apr 21, 2007
Messages
217
Re: Seafoam usage

It is a 1972 9.8hp mercury 110. It starts fine but cuts off unless I pump the primer bulb. I have replaced the diaphram, fuel lines pulsator line, gas tank has checked out fine, new gas, compression is 120 psi on both cylinders. Someone on my job said that a dirty carb or a float that is not moving right could give the same symptoms as a bad fuel pump. How hard is it to diagnose and clean. Thanks for everybody's input!!!
 

Plainsman

Rear Admiral
Joined
Apr 2, 2006
Messages
4,062
Re: Seafoam usage

A sticking float could cause the problem. The carb is not so hard to rebuild. Make sure you get a manual for your engine. The merc manuals are the best.
 

starkyb

Petty Officer 1st Class
Joined
Apr 21, 2007
Messages
217
Re: Seafoam usage

Is the float housed in the silver cylinder shaped part directly connected to the fuel pump with a short hose and how will I be able to tell if it is stuck and what other places in the card need to be checked and cleaned. What do you recommend using to clean it.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: Seafoam usage

Sea Foam has been around for a very long time and has been in probably 100's of thousands of engines. I run it in everything I own that has combustion and it only helps, and helps greatly. It was made for outboards but look on the can for it's applications.

I'd dump the fuel and start over using Sea Foam in the new fuel purchased from a reputable source....where there is a lot of traffic so you know that you are getting fresh fuel.

Also, over the storage, you could have some cracks develop in fuel lines or other fuel handling related problems, like gaskets drying out, carb float sticking and all or sticking rings and or carbon problems.

Mark
 

starkyb

Petty Officer 1st Class
Joined
Apr 21, 2007
Messages
217
Re: Seafoam usage

I took apart the carb and cleaned it up. There looked like some loose debris on the top where the filter is housed and I removed it. I removed the needle and sprayed out the hole and reassembled it. Is there anything I need to do to the part attached to the crank case?
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: Seafoam usage

Probably not if visual inspection reveals nothing.

Mark
 

Harker

Chief Petty Officer
Joined
Sep 21, 2003
Messages
452
Re: Seafoam usage

There is an idle tube that is in the center of the carb..you can see it through the throat of the carb. Did you take that out and clean it well?
 

Zeusdafreak1

Seaman
Joined
Jun 28, 2006
Messages
62
Re: Seafoam usage

Also you say the tank checked out ok. How did you do this? I had a tank that sucked air from the dip tube inside. Buying a new tank and line will eliminate many problems in troubleshooting. I wish I had bought a new tank and line first when I had my problem. If that does fix it, then it must be carb float issue.
 

ronnieboy

Petty Officer 2nd Class
Joined
Feb 5, 2006
Messages
149
Re: Seafoam usage

bet you got some watered gas. been there done that, just change gas and add seafoam, presto, runs like a top, eh, ron
 

starkyb

Petty Officer 1st Class
Joined
Apr 21, 2007
Messages
217
Re: Seafoam usage

The only part I cleaned is the top part of the fuel chamber where the needle seats and where the float is. I reassembled it added some seafoam and it is still doing the same thing. Runs fine as long as I pump the bulb. Could it be that there is something else wrong with my fuel pump even though I put a new diaphram in it.
 

David Jones

Recruit
Joined
Apr 30, 2007
Messages
4
Re: Seafoam usage

Varnish? Needle valve? Jet(s)? Could use a good cleaning. The other alternative is Ring Free (made by Yamaha) works great. also check for loose hoses, could have a suction loss
 

timmathis

Lieutenant
Joined
Apr 24, 2005
Messages
1,295
Re: Seafoam usage

If it runs fine when you pump the bulb. Sure sounds like a fuel pump problem. First check all fuel lines, clamps etc. Also recheck your fuel pump rebuild job, It is easy to put the diaphragm in backwards spring on wrong side etc. Have you tried another fuel tank? Make sure your vent is o.k. after you check all this you should have it fixed. Good luck, Tim
 
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