25hp fuel problem?

Hi,<br />have a 25hp of unknown year(serial a2402771) seems like early 80's.<br />Problem is that engine was running fine and cut out upon backing off throttle while slowing down from planing speed - the prop hit bottom about 30 secs before but kept running (engine ran fine until this happened) checked engine and key had sheared on flywheel(probably from the pissing and farting while trying to restart - flywheel bolt was not tightened properly) . replaced key, plugs , cleaned carb and tried to restart. The engine ran for about two minutes and died and would only run with choke out. also needs mixture screwed all the way in to run.<br />seems to be starving for fuel badly but has me stumped where to start.<br />Sound familiar to anybody? Am thinking of checking fuel pump then reeds then crankcase for leaks.<br />Any ideas or tips would be much appreciated.<br />engine has always run faultlessly until this time and am assuming has been running with mixture all the way in since I purchased it about a year ago.

Re: 25hp fuel problem?

steve first pull fuel hose that comes from pump to carb, pull at carb. Put hose in can and turn over engine.If a good pulsed fuel flow comes its not your pump. The screw on the carb should have been your answer. The screw is for fuel, start at about 1 and a half turns out, if it coughs or sneezes its to lean, if it bogs down or loads up its to rich. If it does not run, carb should be taken off, completely taken apart, soaked in a cleaner, and put back together with a new carb kit.

Re: 25hp fuel problem?

Thanks fishinhole,<br />will check the fuel pump. Already have cleaned carb and blew it out with compressed air (seemed reasonably clean when opened up) will dismantle it again and give it a good soak in solvent to be on the safe side.<br />Noticed when flywheel was off that shaft and seal were pretty oily - not sure though if this had been oiled intentionally by somebody before me or is the result of a leaky seal. As a matter of interest(I forgot to check at the time) is the seal replacable from outside or is it a split the case job?

Re: 25hp fuel problem?

Hi Steven....always nice to hear from a boater down under.... <br /><br />Don't accept "resonably" clean for your carby. If you had to pull the choke to get it to run, then you have some "gunk" pluging things in the carb. Get a rebuild kit. Pull out the soft plugs, there are two...one on top and one on the starboard side of the carb. Blow out all passages with carb cleaner and follow up with compressed air.<br /><br />Your sheard flywheel key probably happened when he prop struck "ground". Be very certain that the flywheel nut is torqued to specs.<br /><br />And if ya' don't have one, get a manual. Will pay dividends in the long run. You can get the generics from here, on iboats or see the links below for OEM manuals which are the preferred manuals.<br /><br /> http://www.marineengine.com/manuals/johnson/ <br /><br /> http://www.kencook.com/contactus/Contact.htm <br /><br />Good luck and keep us posted....thanks.

Re: 25hp fuel problem?

Thanks OBJ<br />OK it seems its definately a fuel pump problem. On pulling starting with no plugs in there is hardly any fuel coming through.<br /><br />Somebody appears to have put an extra o-ring on the inner part of the round rubber gasket that seals the outer removable filter housing.<br /><br />o-ring has perished and inner part of rubber gasket is damaged where o-ring has been up against it.<br /><br />Also of worry is the compression needed to drive the pump. By pulling starter cord with plugs out and a wet finger over the fuel pump hole in the block it has enough compression to blow past if just pressing very lightly but there is no way it will blow past a hard pressed finger - is this normal or do I have problems with crankcase leaks or something???<br />Will definately get a manual soon.

Re: 25hp fuel problem?

Update - Thanks everyone. As it turns out a good cleaning of carb with solvent and compressed air seems to have solved the problem.<br />Fuel pumps that run on engine compression obviously do not function properly until engine is actually running(pullstart with plugs out is not enough revs or compression to get flowing properly).<br />Went with the cheapest option first and problem fixed.