3.0l Breaking up when warm

[Billyd99]

Hello and thanks for taking the time to read this. I have been having trouble with my boat ever since i got it on the water 3 years ago. It is a 1989 17' Smoker Craft bow rider with a 130hp 3.0l Mercruiser and Alpha One outdrive the engine SN is OC529850. the previous owner did not winterize it on time and cracked the block but he ran it with no issues for a few years with JB weld on the crack. it started leaking again and the starter crapped out so he sold it to me real cheap. I let it sit a few years before messing with it. first thing I did was a brand new Carb since the fuel had gone bad and I fixed the crack again. It was still running bad so I brought it to a mechanic. he found the fuel screen on the carb full of sandy stuff so he rebuilt the carb and i cleaned out the tank and the fuel pump that was corroded inside. I also put a fuel water separator in it to filter the fuel. now the fuel is clean and it will run good for a while but after about a half hour of cruising at around 30mph it will get a few little barely noticeable pops. then It quickly gets worse backfiring, sputtering, and stalling out. It will start right up and idle but won't go much over idle. and the longer i let it sit the better it will run good for

Before I throw any more money at it I was looking for anybody's thoughts as to what it could be. I was thinking maybe the block is cracked inside letting water into the cylinder but the boat ran fine before i let it sit and i don't get water in the oil. Someone suggested that the distributor may not be advancing or something. I'm to the point of looking for a new motor but cant afford it now. any advice is greatly appreciated
Thanks

 

[Inf-2LT]

Re: 3.0l Breaking up when warm

billy, I'm having a problem myself with my boat. I can't open up the throttle more than idle on gear. my boat runs very slow, popps, backfiring, sputtering, and stalling out. I started playing with the timing and it rans a lot smother. try to re-time ur motor and let me know.

 

[fishrdan]

Re: 3.0l Breaking up when warm

My gut reaction to your problem, fuel. You said the fuel pump was corroded inside, that's not good, I would have replaced the pump.Maybe ther's something hanging up in the pump's valves, not supplying enough fuel at high RPM.

Check out the fuel system troubleshooting right here (CLICK ME)

 

[Billyd99]

Re: 3.0l Breaking up when warm

the mechanic I brought it to adjusted the timing when he had it saying it was off but ill check it myself when I get it going

I had been thinking fuel all along but a few of the times I took the line off the carb to check that screen for dirt there was enough pressure to spray out. I will look into a new pump anyway though

Should I bother to keep looking for a new block or could that not be a possibility?
Thank you for the advice

oh I forgot to mention, I can only get it to run real bad in the water and under a load

 

[fishrdan]

Re: 3.0l Breaking up when warm

oh I forgot to mention, I can only get it to run real bad in the water and under a load

... when the fuel demand is high. At idle and with no-load there isn't much of a fuel demand.

I wouldn't worry about the cracked/patched block unless you are getting water in the oil.

 

[Billyd99]

Re: 3.0l Breaking up when warm

alright ill pick up a new pump. everything else in the fuel system is new except the pump and the tank. I do also want to check my timing. what is the correct way to set it? I know on some cars there are plugs or hoses that sometimes need to be removed.

 

[Billyd99]

Re: 3.0l Breaking up when warm

nobody knows how to time it correctly?

 

[fishrdan]

Re: 3.0l Breaking up when warm

What ignition do you have?

 

[Billyd99]

Re: 3.0l Breaking up when warm

I don't know if there's another name for it but it has points and a condensor

 

[fishrdan]

Re: 3.0l Breaking up when warm

There isn't anything to plug/unplug or jumper with points ignition. Just warm up the engine, clip the timing light onto #1 plug wire and see where it's at, the timing is supposed to be 6*BTDC.

 

[dubs283]

Re: 3.0l Breaking up when warm

have you checked the fuel vent line for kinks/blockage??

also - have you performed a FULL tune-up, or just going to check timing?? - your issue could be a faulty coil overheating, then when it cools down the engine runs fine for a bit then acts up again

once the motor starts to act up, check the spark at the coil for a nice blue spark

 

[Billyd99]

Re: 3.0l Breaking up when warm

alright sounds like I got. some work to do when I get home! (I'm relaxing in Naples fl right now!) as of two years ago it has a whole brand new ignition. new points, condensor, cap, rotor, plugs, wires, coil, and battery. when I cleaned out the gas tank and replaced all the fuel lines I did clear out the vent hose. is that only a vent? because sometimes I do get fuel into it...
so I guess ill do the fuel pump, check timing, and make sure spark is good. thanks for all the help!

 

[Billyd99]

Re: 3.0l Breaking up when warm

Alright I finally got a chance to mess with the boat. I checked the timing, it was WAAAY advanced if I had to guess it was probably somewhere around 25 degrees so i set it back to around 6-7 it idles, runs and starts much better but it makes a rattling noise at idle. I installed a new cap, rotor, points, plugs, wires, and coil. I took it out tuesday and it ran excellent. I took it out again yesterday and its back to its old habits :facepalm:. runs fine with no load, but with a load it sputters misses and backfires. I have not tried a new fuel pump yet but I'll look into it. I rechecked my timing again and it looked good but my timing light died after a few seconds. and it is still making the rattling noise that i can't ID

 

[dubs283]

Re: 3.0l Breaking up when warm

25 dgerees BTDC at idle?? - i'm surprised it even ran!!

probably wasn't quite that high but still too high, at higher rpms the timing would be WAY too advanced to not cause detrimental harm to the engine internals

the rattle is probably a bad piston knocking around in the cylinder, bad valve, or a blown head gasket, time to do a compression test on all cylinders

have you checked the fuel pump pressure and vaccuum?? (could be the least of your worries at this point)

 

[fat fanny]

Re: 3.0l Breaking up when warm

It sounds like your on the right track, But! before throwing money at something the proper sequence of events is to trouble shoot the related systems Fuel, Igniton and it's wiring all this info is in a service manual and or the stickies (adults only section) @ the top of the forum. My personal rule of thumb is to do what's least expensive 1st

 

[Billyd99]

Re: 3.0l Breaking up when warm

ya i was thinking the same thing about the timing. I could not even see the timing mark on the crank pulley because it was way up under the water pump pulley. I thought i was in the wrong cylinder till I turned the distributor and I saw the mark coming down. It cranks over waaay better than it did before too, and it runs a whole lot better too until a load is on it. the rattle is only when the timing gets down to around 8 degrees and its worse the lower i go. I talked to a mechanic and he told me it could be from the points gap being off but I've checked it at least a dozen times the past week lol.
For checking vacuum and fuel pressure what would be the best way to go about it? sounds like I'm going tool shopping...

Here's a video of the rattle. its hard to pick out but its there

 

[dubs283]

Re: 3.0l Breaking up when warm

take a read of this:

http://forums.iboats.com/showthread.php?t=283269

hard to tell what the rattle is without being there to hear it first hand, i would definitely do a compression test first, then check the fuel pressure/vaccuum

 

[Billyd99]

Re: 3.0l Breaking up when warm

alright I just did a compression test. they were all about the same ranging from 105 to 110. I don't know if that's where it should be or not. I also put a new fuel pump in it because the inside of the old one was coroded pretty badly. I also replace the lines and clamps just to be sure. I probably won't be able to get it on the water till the weekend but I guess if the compression is no good it doesn't matter anyway lol

 

[Billyd99]

Re: 3.0l Breaking up when warm

oops i was looking at the gauge wrong it was all between 110 and 115 psi. I'm thinking that's low still. can someone verify? I don't know if it makes a difference but the tester has the rubber ends not the one that screws in

 

[dubs283]

Re: 3.0l Breaking up when warm

best to do a compression test with the engine warm, but as long as the numbers are close across the board, they sound okay

with the new fuel pump, did you compare the "feel" of the plunger - like the old one was loose or didn't have the same feel as the new one??