1988 Mariner 8Hp-Carburator/Choke Problems

[frednick1]

Hi again,

You guys really helped me with my past problems and now I have a new one for you.

I found and bought a '88 Mariner 8HP and an almost new 10' Zodiac for 400.00. I felt bad stealing it from the guy. He said the the motor may need some work, but I have worked on engines and I know a little about them. It had a bunged up prop that I smoothed off and the thrust bearing was in backwards and the lower unit was low on oil. Some of the screws on the carb and choke were loose. I pulled the plugs and they were pretty clean and dry. I pulled the gas filter and it was clean. The shift lockout that keeps you from starting it in gear was hooked up wrong. It would engage when the engine was running so when you put it in gear it stopped the engine by dropping the stop cog onto the flywheel. I disconnected it.

I squirted some fogging oil into each cylinder and I put it in a garbage can full of water and started it up. It ran ok. Smoked a lot but ran ok. I couldn't run it fast. Not enough water in the can. I let it run for 15 minutes.

I put it on the Zodiac and took it out to the lake and it started up on the first pull and off we went. It planed out with two people in the boat and felt strong and we were clocking it with a GPS at 17.5 MPH. Not bad for an 8HP and plenty fast for me in the 10 footer. It got pretty greasy when it planes like that. No edges to steer with.

After about 1/2 mile I realized that I had not pushed the choke in yet. I pushed it in and it DIED!!!!

I pulled it out again and it started right up and we headed back to the dock. On the way I tried pushing it in again and it died again.

I think it's the high-speed jets. Everything else would have to be ok for it to run that strong. Right?

The carb would not be difficult to rebuild and it's simple enough but I don't want to do it if it's not the problem.

Do any of you have any ideas about it that might help me? before I tear it down?

Will a blast of SEA FOAM help without a carb rebuild?

Now I feel bad for a different reason. He might have stolen 400.00 from me.

Thanks.

Norm Fred
NW Michigan

 

[jmburock]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

You're probably flooding it when choking while aleady running. If you don't need the choke to start her up, then you certainly don't need it while running. Of course you may want to clean/rebuild the carbs to help alleviate the flooding condition. Are your plugs wet/ fouled? Given the condition of the motor, sounds like the prior owner didn't know what the hell he was doing. I would change the impeller to be on the safe side.

 

[frednick1]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

Thanks JM,

You are right about him not knowing what he was doing. I think he sold it to get rid of it. I think his wife was bugging him to get it working and he didn't know how.

I do need the choke to start it up, and the impeller is ok. The water intake is clear and the coolant water stream is good and steady. The water coming out of it is a bit more than warm at full speed. Not real hot. So the cooling system is working ok.

It starts, idles, and runs flat out with the choke full out but dies when I push the choke in.

Frednick1

 

[frednick1]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

OK, There's more. I noticed that when I press the primer pump, which sits just to the side of the float bowl, with my finger, some gas comes out of the hole that the plunger comes up out of. I can hear it squirting gas into the intake throat but it seeps up out of the plunger hole and bubbles, too.

So there's a break in that diaphragm that is the operational part of that little pump. When the choke is released and that little plunger comes up, it could let air into the float bowl from which the primer pump gets its fuel.

I think that the motor sat for so long, the rubber diaphragms and rubber parts dried and then cracked when I actuated them. However, I think the fuel pump is ok since it ran fine for that first few minutes and sucked gas ok.

Now I am completely convinced that I need to repair the carb. I'll get a kit for it very soon and do it myself.

Frednick1

 

[saumon]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

I've been in the exact same situation (starting/running only with the choke on) on a 1988 Merc. 8 hp. Finally found that the fuel pump diapragm was bad but the primer provide enough fuel tu run when on.

http://www.dougrussell.com/partscat...0,180,200,190,210,70,240,20,30,0,60,160,50,40

only thing you need is #15 Carb GASKET/DIAPHRAGM KIT to overhaul the carb with integral fuel pump. Pretty straight forward job: disassemble, clean with carb cleaner, blow with compressed air, reassemble with new gaskets, install, set the idle mixture srew at 1 1/4 to 1 1/2 CCW from lightly seated and adjust.

 

[frednick1]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

Hi Saumon,

Thanks for the info. It's stuff like your post that really helps out when someone has a problem like this. The link to the schematic was helpful, too. I'll bookmark it for future reference.

When you say the "fuel pump diaphragm was bad", you mean the main fuel pump not the primer pump?

I ask because I would think that when it was running flat out with the choke pulled out and primer pump depressed and the gas is being diverted through the primer pump, it would still need the fuel pump working to get it to the primer pump through the float bowl.

And even if it was doing what you say, when I push the choke in, there would be enough fuel in the bowl to run for at least 10 seconds or so. But it DIES Immediately! when I push that choke in at high speed.

I really think that the high speed jet is clogged and the engine is getting fuel through the primer pump system to run fast.

But hey, it really doesn't matter. You are right on. Taking it apart, blowing it out and putting in some new rubber parts and gaskets will fix it no matter what the problem is. (I hope!!!) :>)

I can get a carb kit on eBay for about 30.00 and sometimes a lot less.

I'll wait a few days to get one. I've inhaled way too much stinky gas/oil fumes in the past few days and need to recover a little. I've developed a hacking cough from this project.

Thanks again,

Frednick1

 

[saumon]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

No problem! Like you said, no matter what was the problem, it will probably be solve by a carb overhaul...

 

[frednick1]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

I'll let you know what I find when I crack that little honey open.

 

[frednick1]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

Frednick1 again,

I got the gasket kit on Ebay (30.00).

I took the carb apart one section at a time and replaced the parts exactly the way the old ones came off. I also had a good diagram in an old manual I had from yeas ago that helped.

After several attempts, I got it all back together right and pressurized the float bowl and it didn't leak. I think the carb was on and off the motor at least 4 times because of one screwup or another. It's hard for me to believe I could be so inept. I was a surgeon in a former life. But I finally got it going.

There were 3 gaskets left over that were for some other carb. They certainly don't fit the one I have.

All I found when I opened it up was that the primer pump diaphragm was torn and the high speed jet looked dirty but didn't seem to be clogged. The float bowl was pretty clean. No debris of any size, just some dusty, fine particles that wiped and blew out.

I blew out every little port and hole and little passage until they were clear. I put it back together. I may have cleared some small passages that I didn't even realize were blocked. Who knows?

It starts, idles, runs fast and shift just like it's supposed to. Smooth as silk, no smoke.

I adjusted the idle mixture, set up the idle speed and advance limiter.

Anyway, thanks for your help. Good advice again. YOU GUYS ROCK!.

When I get the gas smell of my hands, I think I'll going fishing.

Norm

 

[wheasle]

Re: 1988 Mariner 8Hp-Carburator/Choke Problems

GAS SMELL ON HANDS I INVENTED A PRODUCT JUST FOR THAT ....
www.naturesfresh.net hated that gas smell.