94 3.0 mercruiser,Runs 5-10 min.Then dies out?

[danyboy]

Hi,I have a 94 glastron elite 3.0 merc. And im new to this site,Iv spent many days (hrs) looking over post related to the problem im having with my engine.and from what i see this is a very common problem with the 3.0 mercs.when i take her out on lake she runs for about 5-10min. and then starts to hesitate and dies unless i pull throtle back to neutral,it idles fine and revs in neutral fine also, its only when i put engine under load that im having this issue? This is what iv done so far (1) new plugs.(2)wires.(3)cap and rotor.(4)fuel filters.....from all the blogs iv read its got to be (1.) fuel pump.(2.)carb.(3.)anti-siphone valve.(4.) cloged pick-up tube screen.(5.) faulty module in distributor(when it gets hot). my plan was to start with the simple and work my way up! I have heard that i can use a gas can and put the fuel line in it to eliminate pick-up tube and anti-siphon valve from the factor? and if problem still remains than that leaves fuel pump or carb right? also this model of glastron has no access door to get to top of fuel tank??( only has door for tank float for fuel gage) so will i have to cut my floor out to get to my pick-up tube and anti-siphone check valve???(can they cut anymore corners building these things?)

 

[6meter]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

Before cutting holes in floors, do the seperate fuel tank test first. When it happens, loosen the fuel fill cap, better? Still could be on the ignition side to. Coils can cause your symtoms. Haven't heard of anybodys ignition module frying.

 

[danyboy]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

Well i had time to take my boat back out on lake today to do the seperate fuel tank test and after running 4,500rpm for around 5-8min. it started to do the same thing!!! cutting out or dying out?? sometimes if i pull back on the throtle to 1500-2000rpm it will run for a good long while smooth with no hick-ups but as soon as i try to go over 3000rpm it cuts out again,but sometimes even if i pull back on throtle it will die,but will start right back up and go again for awhile at the 1500-2000rpm but then again sometimes not ( no consistency to it )and letting it sit does not help any,i let it sit for 30-45min started it up and took off and instantly does the same thing??? I know i eliminated the pick-up tube,anti-siphon valve,and water in fuel from the factor by using a seprate fuel can......so in my mind im thinking fuel pump?? because its like it cant keep up with the higher fuel demand over 3000rpm??? I looked at adult only thread about testing the fuel pressure with gauge,hoses,ect. but i got lost reading it ( a little to complicated looking of a contraption to me) but i think thats all thats left if its not the fuel pump is carbie,or coil right??? i changed fuel filter( inline up by carbie) i almost forgot i also changed out that vinal hose that runs from top of carb to the top of the manual fuel pump( old hose yellowed ) but i dont know if there is soposed to be fuel in it or not( with engine running there is no fuel or anything in it...since it came out of top of carbie i figured it was some kind of overflow or something??? So anyway just wanted to get an experts opinion on this!!!! its starting to get fustrating and I dont want to just start buying parts i dont need...and i dont have the cash to take it to the shop and say fix it any help appreciated alot..thanks, danyboy..

 

[danyboy]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

also i noticed that water was getting into boat from rear but was slow and could not tell where it was coming in? untill i pulled out of lake and upon inspection seen that the shift cable bellow is broke in to peices so looks like i have to pull stern drive also!! is the broke shift cable bellow letting the water in engine capartment??? i just orderd bellow kit and gimble bearing($100.00) and the alignment shaft tool($40.00)and hinge pin tool($12.00) missing anything????? i already watched about 10 vidios on u-tube and will start on that as soon as parts get here,just wanted to get some advice on this and cutting out issue but not having to much luck on the replies in here???

 

[blacklab75]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

I just had the exact same issues with my 3.0 and it turned out to be the fuel pump. The sight tube never showed any signs of fuel in it. So I rebuilt the carb, checked the coil, ignition, new plugs, fuel lines, tank, timing and so on. Then during all my fiddling I saw fuel spit through the tube for a few seconds and then it stopped. I tried several times to get it to reproduce the spit and it took some effort.

I replaced the pump and now it runs perfectly. I opened the old pump just to see what was going on and the top of the upper diaphragm had a little red gunk.

My 1st instinct was the fuel pump and their's alot to be said about reading posts. Sometimes too much information can be a bad thing.

 

[danyboy]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

Thanks blacklab, yea your right( input overload),fuel pump is what i thought also,so just orderd one yesterday,will get here monday and i will know for sure after test drive mon afternoon,i will let you know if that fixes her,if not i will rebuild the carbie, and thanks for the reply,i was begining to think i was being discriminated against..(hahaha)

 

[tschmidty]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

No discrimination, but frankly I just read this post and figured you were on the right track and looked to be testing the right thing. I would also have said fuel pump which is not necessarily cheap but if you are not up for pressure testing replacement is your only option. 5-10 minutes is not enough time to heat soak a coil so fuel pump looks like the most likely culprit.

And a leaking shift bellows will definitely let water in your boat. If not already said, replace the other 2 bellows while you have it apart for sure. In fact I'd probably replace the water pump impeller too while I had the outdrive pulled. Read posts, remember to heat the hiinge pins to loosen the loctite, use the bellows adhesive and be prepared to fight pretty hard to get them on. And you'll love the feeling knowing that all the maintenance was done.

 

[danyboy]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

thanks tschmidty, and just joking about the discrimination thing (haha), And i will for sure change all bellows while its off,and your absolutly right about the feeling good and having peice of mind knowing its done, and done right the first time!! heck i fill good every time i fix somthing myself that i dont have to pay someone else to do or fix for me(boat,car,home,ect.) thanks again, and i will keep posting results as i go, hope the fuel pump does the trick!!! im near austin,texas and its like 102 degrees around here these days,so cant wait to get back out on the lake...Thanks again..

 

[fat fanny]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

Don't shrugg too much info. Everything I have learned and done myself I learned from here the only work I have ever contracted out was the head work. Just remember one thing that the ability to learn to troubleshoot will save you thousands in the long run! just getting a few simple tools and reading the proceedures or printing them and using them as you work helps the understanding curve. Also trying the simple and least exspensive things first is the best train of thought that's why learning the troubleshooting techniques is esential to the process. Your issues I have experienced over the last 10 years with the same rig and she's still running because I was patient and have barly spent over 500 on maintenance since I bought the boat. But to get to the point I think your on the right track but don't rule out the ignition mod I had one that would intermittently over heat and wouldn't allow advance to the timming leason learned buy OEM when you replace electricals. Also by replacing the fuel pump and this doesn't solve the issue you need to do the troubleshooting test on the coil (cost nada!!!) then if not solved carb rebuild (cost 50 $ ?) after that it could be the electrical connections I have also experienced these issue from them Good luck!!!

 

[danyboy]

Re: 94 3.0 mercruiser,Runs 5-10 min.Then dies out?

ye,ha, well guys i can put this thread to bed now!!! I got my new fuel pump in today, and put it on, took her out to the lake,(still had the seprate fuel tank in engine compartment) rode her at WOT for 30min,then backed off to about 3500 rpm for 10-15 min.killed it and let the kids swim for awhile( 30.min) she started right up and cruised around another 15-20 min. And she did not die out on me or bog out,ect.and the fuel pump seems to have fixed it, so that issue is resolved thank god, and i can hook my inboard fuel tank back up.....but the funs not over yet!!!! im having another issue with it now??? but i will start a new thread for that problem, just wanted to tip my hat to all who took time out of there bussy days to help me with this issue. ( especially fat fanny ) I think this site is owsome and im sure glad its here for us all, thanks a million comrades.....