Engine advice

[michael1923]

A few months back i bought a suzuki DT75 hp, when i purchased it, it had been sat around for about 18 months.
When i first started it, it started first time but ran really bad very knocky at low revs, and would not rev up at all, it ran on when turned off and would not idle without some quick starting and then trying to keep it running using the throttle on the engine..

At first i put it down to needing a general service.

I have done the following

2 new sets of spark plugs as per manual (dealer spec )
New spark plugs caps
New gearbox oil
Timing checked and adjusted
Carbs taken off and cleaned
Idle screw set 1 1/2 turns out as per manual

Now in neural starts and stops great, revs up great, abit knocky at low revs but this goes when reved up.

However put it in gear at take the boat out for a run, it lacks all power (because of the revs) it just will not rev up above probably 2000- 2500rpm. And prob does and estimated 7 knots, I am now not sure where to turn. I do not have a large budget but do have the time on my hands to slowly put things right.

I am about to check fuel pump and filter as this is mentioned in the manual, and will also add some jubilee clips as some of the fuel lines are missing them, but they seem to be really tight and i dont think its that but will add the clips just to make sure i can rule this out. Also worth noting is it is missing the air filter.

Any advice would be greatly appreciated
Mike

[squidlips]

have you checked the compression,remove all spark plugs and crank it over at wide open throttle?

[michael1923]

I haven't done a compression test yet, do you think that is my next step
Mike

[squidlips]

yes mate deffinantly,it will show wheather a piston has scored the bores or if the piston rings are stuck in their grooves,before you throw any more money at it.
an engine needs 3 basics to make it run.do you have a spark?petrol?
finally compression.

[monkeynuts]

karls not wrong
do a compresion test and find out if your flogging a dead horse (i think it should be around 100-150 psi but double check that with a main dealer), next check fuel lines for blockage, air leaks or the pipes colapsing/ going soft
another little thing that can do what you talk about is if the gasket between the carb and engine is missing or badly damaged it will suck to much air and not enough fuel, but this will normaly come with bad running at idle too
good luck

[michael1923]

Thanks very much for that, waiting for my dad to come down now with his compression kit.

Mike

[michael1923]

Hi thanks everyone for the help, given up now.

I'll try and pick up a cheap engine january time when i've saved a few quid and then maybe i'll be out and about.

Theres water coming out of the exhaust so to serious a problem for me now.

Thanks for the help
Mike

[squidlips]

mike there should be water coming out of the exhaust as it cools the exhaust gasses passing through the leg.

[michael1923]

Thanks for that, i've given up now.

I'm going back to beach fishing, sometimes its worth while sticking at what your good at.

I've been wrongly dreaming about boat fishing for 15 years and i've now decided to go back to beach fishing, hopefully i'll recover my outlay.

Mike

If anyone wants any advice beach wise in the lee on solent, gopsort area please ask.

[easytow]

Don't give up just yet! Check your electrical connectors. Have a look for all the mult-pin rubber connectors and fuse connectors. They may be corroded and causing a poor connection that can appear like a fuel problem. This can make the motor fail to rev out properly as the connection breaks down under load. Take them apart, clean them and give them a coat of vaseline. Also check the spark is not arcing. (best done in the dark) Worth looking at the HT coils and the leads too, to see all is sound. Then try your motor again.

[radiowaves]

hello,i just fitted my engine (70hp)to my boat and found the same problem,i was doing around 8knotts and 2500rpm full throttle,i was advise to change my prop as it was to high a pitch,changed the prop and now doing 20+ knotts so think about the prop as well,