1985 30HP Mariner - Poor Power

[txduckslayer]

Hello everyone, I was turned on to Iboats while in search of my boat and I found the best duck hunting boat ever.... well until now and I think shes sick

My motor is a 1985 30HP Mariner with a pull start and a tiller handle.

The motor will start on the 2-3 pull every time (yes even when cold!) it will idle all day in and out of the water just fine. When I put her in gear it wants to die on me, I have to get my RPM's high and throw it in gear to go anywhere. It also seems to have a poor hole shot. Also I do alot of duck hunting in the marsh with it and if I stop and try to power up in grass/mud my engine dies, other boats seem to have the torque to get through it (my buddies boat is 25hp and it does just fine). Finally I feel like i get poor fuel economy, i will use 1 gallon a mile or so. I hope i provided enough detail for someone to shed light on where to start. I am going to take apart the carb tonight and clean it real good, whatelse where else should i look?

 

[Maxz695]

Re: 1985 30HP Mariner - Poor Power

check the filter after cleaning the carbs set mixture screw adjustment to 1 1/4 turn out from a light seat and then adjust for best idle. another 1/8ths turn may be nessecary for acceleration. do this when under power to get the best take off.Check for leaking lines clogged or closed tank vent. The fuel pump may be getting weak and may need attention as well. Have you checked the plugs lately? Spark plugs after time will fire up to a certain pressure and then cut out when resuming the lower pressure they will fire again. Just some simple things for you to consider.

 

[txduckslayer]

Re: 1985 30HP Mariner - Poor Power

check the filter after cleaning the carbs set mixture screw adjustment to 1 1/4 turn out from a light seat and then adjust for best idle. another 1/8ths turn may be nessecary for acceleration. do this when under power to get the best take off.Check for leaking lines clogged or closed tank vent. The fuel pump may be getting weak and may need attention as well. Have you checked the plugs lately? Spark plugs after time will fire up to a certain pressure and then cut out when resuming the lower pressure they will fire again. Just some simple things for you to consider.

where are the mixture screws located at, sorry i dont have my blowout to post a link on here to see. i have two brass looking set screws with springs on them, they are on both sides of the carb and horozontal.

Looks like part 12 or 10?
Mercury & Mercruiser Parts, CARBURETOR, 30 HP


i changed the plus about 3 months ago.

Lets talk fuel pump, how do i test it?

Thanks for taking time to help me!

 

[Maxz695]

Re: 1985 30HP Mariner - Poor Power

there are a couple of ways that you can check it. sueeze the bulb and after it gets firm keep presure on it for a while to see if it,s loosing firmness then remove the line out and turn the motor over to see if fuel is being pumped. It may pump but it may be streched out and not pumping with good pressure. Here is a picture of my 70 HP mixture screws they have springs on them It may give you an idea on what to look forView attachment 176035 Thie screw on the right is the mixture screw on mine

 

[Faztbullet]

Re: 1985 30HP Mariner - Poor Power

Check compression as it sounds like it running on one cylinder, dont worry about ignition as its working.

 

[Maxz695]

Re: 1985 30HP Mariner - Poor Power

Part 10 is the overflow jet don,t mess with it. It tells you when the needle seats are not sealing gas comes out of it.

 

[oldman570]

Re: 1985 30HP Mariner - Poor Power

Set the idle jet screw as Maxz states and adjust the idle set screw so the motor will idle between 650 and 700 with the motor in the water and in forward gear. Use Seafoam or equivalent mixed in the gas along with the oil should help decarb the motor and clean the internals up. doing the compression test is always the best to determin that all the internals are in good shape before spending time and $ on things that will not realy fix what is wrong with the motor. When running a motor in weed choked water along with shallow depth is alway a hit and miss when it comes to getting the boat to move. Motors equipet with a shallow drive are alot eiaser to get moving compaired to one without shallow drive. The weight of the whole unit is another factor in just how the boat will preform. JMO
Oldman570

 

[MH Hawker]

Re: 1985 30HP Mariner - Poor Power

It sounds more like its time to rebuild a carb.

 

[txduckslayer]

Re: 1985 30HP Mariner - Poor Power

Well, on friday I took the carbs completely apart soked them in solvent put everything back togeather she starts on the second pull every time now! I went a head and did one more step the decarb process, lets just say i didnt warn my wife and when she looked outside she thought i had caught the whole house on fire. i did 2 compression checks before and after the decarb process, first one was about 120psi on both and after the process they both bumped up to about 135ish psi. So after letting the decarb process sit over night I took the boat out for a test run on sunday, let me tell you it still smoked at the ramp! she seemed to run a little bit better it was just me in the boat, I didnt have decoys/dog/gun so i couldnt load her down with weight.

on another note, ever since I had the motor i really have never had reverse. I have reverse but I cant give it gas, if i give it gas it eaither A) pops out of gear OR B) grinds my gears. So i have learned not to give it gas when in reverse. should be looking at a bad clutch dog or bad reverse gear?

 

[Maxz695]

Re: 1985 30HP Mariner - Poor Power

Bump Thanks gerry musta woke up to early today here. There may be damage to the reverse lock down cam that may be restricting the shaft shaft from fully engaging reverse. This will be appearent when you do the cable adjustment if thats the cause for the restricted reverse issue. Soory for the mix up but still there is the shift handle and the bushing for the shift shaft that could be checked

 

[carholme]

Re: 1985 30HP Mariner - Poor Power

Well as you said in your first post that it is a tiller handle, i doubt you have to worry about the cable adjustments.

Are you sure it is a 1985, what is the engine s/n? If it is an '85, the following applies:

The adjustment for gear synchronization is done at item 21 in this link:

Mercury & Mercruiser Parts, GEAR SHIFT LINKAGE, 30 HP

You can also check for excessive wear on item 2 which is the shift cam.

Here is a link to the condensed version of the service manual. Download it soonest to your computer as the link is short lived.

Small Engine Repair Reference Center Home

See page 123, bottom right hand column for gear sync.

Gerry

 

[txduckslayer]

Re: 1985 30HP Mariner - Poor Power

the SN is 689 s 026456, I might add that it only slips/pops out of gear while in the water. i can run it with power on the hose all day long, just a annoying little bug in the motor. i will try to adjust that, the only time i messed with that was when i changed the waterpump. Thanks both of yall for all the help.

Gerry i see you are in Ontario, you do any hunting ever?

 

[carholme]

Re: 1985 30HP Mariner - Poor Power

slayer;

1985 it is with that s/n, therefore the information in my previous post is valid.

Sorry about the hunting but gave that up many years ago. Where I live here in the North, the highways are full of hunters coming up during the season and with all of the "sound" shooters out there, it can get quite dicey. Fishing is much better, nobody shooting at you!

Gerry

 

[txduckslayer]

Re: 1985 30HP Mariner - Poor Power

i wouldnt mind fishing up there eaither! i will try to adjust the linkage tonight, and get back with yall!