suzuki 70 4-stroke cutting out

gaelforce · 24 March 2002, 20:10

after the winter break (didn't drain the petrol) on the first run at sea my suzuki 70 started idling roughly before cutting out. it started again and ran no bother but i was a bit worried obviously. today i started her out of the water and she ran for 5 mins before stalling. started no problem again then ran for 2 mins; 30 secs and now she cuts out on starting. i cleaned all the plugs, checked breathers but no good. Got a mechanic looking at her next week but any ideas? I suspect the fuel but it all looks fine.

Jono Garton · 24 March 2002, 20:23

Hi

Have you tried totally running the carb dry? ie disconnect the fuel pipe and leave engine running till stops. Then connect and try.

Hope you sort your problems out..........

GraemeCooper · 24 March 2002, 20:52

I think your problem may well be 'stale' petrol.

The Old 4 Star fuel did not surffer this problem, but the new Unleaded contains high amounts of water, and, if left for any period, 'goes off'.

I discovered this to my cost with a lawnmower a couple of years ago, and the local dealer merely emptied the fuel, replaced it and all was well. I felt a bit of an idiot.

I have an old Military Landrover that is used only rarely, and I have found an additive that removes the water and therefore prevents this from happening.

You may find you will need to get this additive - available from any garage, or your local marina, and run it through. If you can get rid of most of your old fuel that may also help.

Brian · 25 March 2002, 14:25

I've got a theory. Same thing happened to me.
The cause was a small "tear" or "pinprick" in the furel line. You wouldn't credit it, but that was the problem. Easily tested by running a diferent fuel line from a tank directly into your engine fuel coupling. Even the smallest amount of air getting into the engine will cause it because it's easier for the engine to suck air than it is for it to suck petrol.
Good luck and lets hope its resolved soon.

gaelforce · 30 March 2002, 15:37

thanks for the help lads. i ran it dry jahno but the same trouble again. i supplied new fuel graeme but no improvement. as for a prick brian, i fell a bit of one myself but i cannot find one on the fuel line. one thing that puzzles me is that when i squeeze the handpump (the yoke that looks like a handgrenade) i notice it doesnt go completely hard and i seem to remember it used to. i cant find a leak between it and the carb though. mechanic coming monday thank god.

thewavehumper · 30 March 2002, 19:24

Gaelforce
regarding your comments about squeezing the handpump I think it's just as well that Nadia didn't read it.

Seriously though my son and I will be out on Monday in our ribs in the Solent, so if you need an escort while you give your engine a sea trial it will be no problem.

Garygee · 31 March 2002, 17:00

Hi gaelforce

Its worth trying pumping the primer bulb while the engine is running, say every 15-30 seconds.

By doing this you can rule out the fule pump, which the diaphram somtime perish when stood, or holes in the fule line as prining would push fule out whaile the normal pump would suck air in.

It may be worth waiting until the motro start to splutter then pump the bulb to see it recovers, if it does its likly to be fule starvation cause by somthing.

The othet thing that can help are the 2 stroke fuel system cleaners. These help remove old oil, left after the p[etrol evaporates and other goo from the engine. However they can take several gallons of fuel to do a good job so may be a problem.

Hope this helps Gary

Ribald · 02 April 2002, 10:55

Could it be that the non-return valve in the primer bulb has failed and is letting fuel run back to the tank. It would appear that your short time of running is on carb contents only. This would also confirm your comments about the bulb not being as hard as it used to be.

Or has your engineer sorted out the problem?

batfalcon · 03 April 2002, 04:34

the fuel line from the carbs and pump the hand pump. If the fuel come out from the pipe then the problem must be in the carbs. First "feel" the fuel. Smell it. Does it smell like gas or it seams like water. If the fuel is ok, then try to blow some air in the carb(s) by attaching a spare fuel line on the carb and blowing your breath in it. If you feel that the air IS NOT inserting, then the carb's needle inside the bowl is blocked in place and doesn't let the fuel to flow freely.
Now if you feel that you can go on repairing, tell me and I'll try to guide you.

Alan Mckewan · 03 April 2002, 05:52

The Suzuki 70 4 stroke doesn't have any carbs! Anyway the seal at the fuel connector is worth checking- it is a common fault to get slight damage to the o ring seal and draw in air at this point and cause stalling.

batfalcon · 03 April 2002, 09:46

for the trouble I made. Thought I could help.

thewavehumper · 03 April 2002, 12:50

Gaelforce, I have to know what was the solution?

gaelforce · 08 April 2002, 01:14

wavehumper. i so want to get to the bottom of it and say 'yeah, this was the problem!' but i can't! first of all thank u to everyone who replied to me. everyday i would go to the boat and try out what you all said. the mechanic came and went. he recommended a suzuki diagnostic check. boat currently off west coast of ireland and this will be done @ first opportunity. in the meantime the damn engine has , how can i put this, improved. alan mck u are right the fuel connector is a dodgy affair and has been given the twice-over but still is under suspicion. graeme c, the new fuel has done no harm at all; jahno et al. i now rate the fuel supply system as absolutely critical but lads believe it or not the major improvement came when i pulled out he bastard emerg. cord stop and put it back again. it should be digital (on or off) but it's kind of analog and has a sticky feel to it. i wish i could say it's perfect (and lets face it - it's a world-class engine, controlled by a chip which knows if the crew are farting and adjusts the intakes accordingly-so it should be) but it now needs priming when we start off and gives an odd splutter. THAT SAID there is a massive high over ireland at the moment and we spent the whole day bumming round galway bay. glorious. what can i say. we are logical men on this site and we know there is a straightforward reason for everything. i've lost a lot of that very unscientific notion - trust - in my engine though. if i finally get to the bottom of the problem, or my psychological disposition which thinks i've got a problem, i'll let ye know. good luck and sincere thanks.

gaelforce · 08 April 2002, 19:20

Batfalcon - Dont feel too bad about not realising the suzuki 70 has fuel injection instead of carbs. I didn't realise despite the fact that
a) I once did know
b) I own it
c) I read the manual
d) It says 'electonic fuel injection' in inch-high letters on the cowl.