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A royal headache - Mariner 1997 40 HP.

D

Damien.

Member
Elo lads, im hoping I can get some help on this one because I am stumped.

The engine is a 97 Mariner 40 HP 2 Cylinder, 2 Stroke.

I have just done an electric start conversion for the customer and this is the first time he's heard the engine running for about 14 months. The problem is, its running like an absolute dog.

I have drained the fuel system and refilled with clean fuel, I have checked hoses, spark and adjustments but nothing seems to improve the running of this old beast.

The compression is good and the spark looks OK.

Any ideas would be great, ive hit a mental block and have given up.

Cheers.
 
Re: A royal headache - Mariner 40 HP.

You did not state if you actually rebuild the carb or not.
Does it start easy and idle well?
 
Re: A royal headache - Mariner 40 HP.

All I have done with the carb is cleaned it out with an air line, it has not been rebuilt.

The engine starts on the button but the idle is rough.

It surges some times, as if someone is applying revs for a few seconds.
 
Re: A royal headache - Mariner 40 HP.

Pull and thoroughly clean the carbs and it will run like a champ again (and you'll be a hero).

Jeff
 
Re: A royal headache - Mariner 40 HP.

Plus 200 bucks richer if you charge the "going rate" for a carb rebuild :)
 
Re: A royal headache - Mariner 40 HP.

Will be stripped the carb and cleaning in the morning.

I will let you guys know how I get on !

D.
 
Re: A royal headache - Mariner 40 HP.

Not much luck.

Ordered a fuel pump and carb rebuild kit today, will fit them and see if I get better results.

I did notice the spark seems to be weak, its orange and not the white/blue it should be.
 
Re: A royal headache - Mariner 40 HP.

orange spark is bad. You'll get incomplete ignition at best, have you changed the plugs?
 
Re: A royal headache - Mariner 40 HP.

Spoke too soon.

Engine is still running like a bag of nuts.

Had a second opinion on it today, the chap mentioned that the crank seals might be shot. What symptoms would this give ?
 
Re: A royal headache - Mariner 40 HP.

A blown seal can cause -

crappy idle
backfire, cough or sneeze
low power at higher rpms
bogging

You might notice an abnormal oily film either in the lower cowl (bad lower seal) or all over the powerhead itself (upper seal) - kinda the same consistency as if you really gave things a good spray with fogging oil or WD-40.

It's caused when your gas/oil/air mix gets blown past the seal. The gas evaporates, the air goes away and leaves the oil on everything. This can confirm a bad seal if the other symptoms exist and you can find no other cause for the issues...
 
Re: A royal headache - Mariner 40 HP.

This is officially the worst engine i have layed hands upon.

Still not running right after the following;

Electric start kit inc enricher valve, full service, new fuel pump diaphrams and a carb rebuild kit.

The engine will start on the button using the "push to choke" option on the ignition barrel. This works by bypassing the carb and spraying fuel directly into the inlet plenum. Once the engine uses up this fuel it gives off one massive rev then dies. I have tested the fuel pump by pulling the outlet pipe off and cranking the engine over, fuel it pumping out at a good rate. From what I can tell this is down to the carb not spraying the fuel into the engine !?

Even though its had a rebuild kit, could there still be existing issues with the carb ?

I need some ideas lads, really struggling here.
 
Re: A royal headache - Mariner 40 HP.

The carb was filled with gas? Or the float is set wrong. Set to 9/16". Set the fuel screw to 1 1/2 turns.
 
Last edited:
Re: A royal headache - Mariner 40 HP.

If it runs on enricher but not otherwise, it's not getting fuel out of the carbs. The engine is clearly drawing and burning fuel on the enricher, so it must be the carbs.
If it's not carbs, you must have a big vacuum leak somewhere.

Regards, Andrew.
 
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