3.0L still cuts out after replacing almost everything all my searching has told me to

First Id like to say I have a member for a little while now and have been searching this subject since Day1...

I am by any means no expert on boats but have a decent knowledge with Car/Truck motors and as much searching as I have done on here I had to post for myself instead of basing my problems off everyone elses.

So my Story...

I bought a boat the end of last year from an older man just trying to get rid of it after sitting for 2 years.

1988 16.5' Glassport
3.0 Mercruiser

Ran great in the driveway (of course) and actually ran great the first couple times I took it out, hitting the 4200-4600 RPM mark no problem.

After a while it started cutting out around 1900 RPMs and if I could feather the throttle through, it would pick back up and run fine. Then it slowly started to get worse, and then would only top out around 3900/4000 RPM mark. I searched this and other sites like crazy and replaced a lot.

I replaced:

Plugs
All the filters (separator, fuel pump, carb)
Cap
Rotor
Points/condenser
Set timing

I had the carb rebuilt, and the float had a gash in the side, so I thought maybe it was flooding since around 1900 is a pretty average range when the bow is up just before plane.

The guy I bought it from included every receipt and all the manuals for the boat so I have been doing lots of reading and I just can't figure it out. He replaced the fuel pump which would be about 3 years ago now, so that wasn't really on my list of priorities.

My fuel gauge does not work, so I wasn't sure if a sending unit would cause this? And I have also been told, that through the years, the fuel line coming from the tank gets old and can collapse. At this point I am open to anything, Money is a little tight at the moment but hopefully in a couple weeks I can try a new pump, but I still don't think that is the problem, but I am just trying to scratch off any possibilities. In the meantime though, I am just trying to think of any easy, cheap or stupid fixes I may have overlooked.

Any help would be greatly appreciated. Thank you in advance.

Tom

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

A simple test to help diagnose the problem would be to bypass the fuel tank and line by running temporarily from another tank. A portable outboard motor tank can be rigged directly to your fuel pump. If the problem disappears, then you have narrowed your list of trouble sources down. In fact, even if the problem doesn't disappear, you have still narrowed your suspect list down.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Oh yeah - welcome aboard!

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Hey Thanks!...

I have been skeptic to say anything, I do not know much about boats, but I have learned a lot over the past 9 months or so. That will work without using a sending unit or anything? I have thought about that, but I assumed that the sending unit played some sort of part.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Time to stop throwing money at it and do some testing. Was there any water in the carb? The remote fuel tank will tell the story of the fuel system before the pump.
The 3.0L engines do not have water separating fuel filters from the factory, so any water goes directly to the carb. Does your's actually have one???? I see you mentioned one. If you do, have you emptied the contents of the old filter into a clear container to check for water? (DO NOT reuse the old filter after you empty it)

Also , hook up your dwell meter and run the engine. See what it reads at idle rpm, then when running see if that number remains the same at the higher rpm. If not, it could be worn distributor bushings.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

I replaced the water/fuel separator, and when I emptied it, there was no water in it, I didnt reuse the old one.

I had it rebuilt by a local marina, so I do not know if there was water in the carb, I just received the float back showing me the large gash in the side.

I am sorry I do not even know what a Dwell Meter is....timing light?


Sorry for the delay....Computer is down due to the joy of painting.

Don S said:

Time to stop throwing money at it and do some testing. Was there any water in the carb? The remote fuel tank will tell the story of the fuel system before the pump.
The 3.0L engines do not have water separating fuel filters from the factory, so any water goes directly to the carb. Does your's actually have one???? I see you mentioned one. If you do, have you emptied the contents of the old filter into a clear container to check for water? (DO NOT reuse the old filter after you empty it)

Also , hook up your dwell meter and run the engine. See what it reads at idle rpm, then when running see if that number remains the same at the higher rpm. If not, it could be worn distributor bushings.

Click to expand...

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

tshaw84 said:

I replaced:

Plugs
All the filters (separator, fuel pump, carb)
Cap
Rotor
Points/condenser
Set timing

Click to expand...

When you replaced the points - how did you set or adjust them? With feeler gauges? That's fine - but a more accurate way to adjust the points is with a dwell meter. It measures the amount of time the points are closed - (or is that open? I don't remember. ) - and is specified by degrees. With electronic ignition being the standard for 30 or 40 years now in the automotive world, dwell meters are not as common and many do not know how to use them. There is a sticky at the top of the page regarding working with a points style ignition.

tshaw84 said:

That will work without using a sending unit or anything? I have thought about that, but I assumed that the sending unit played some sort of part.

Click to expand...

Regarding the gas and using a remote fuel tank - your sending unit only affects your fuel gauge - it has nothing to do with the engine's performance.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Great, I understand...kinda...lol

Which would explain my fuel gauge not working or sometimes reading half.....


Yes I used feeler gauges...I was going to go electronic...but after throwing a bunch of money into this thing already, I wanted to find the problem first...

I will have to look into a dwell meter, I honestly have never heard of them...would the points being off cause a dead spot in accelerating? everything I have done so far seemed to help a little, to where it doesnt completly cut out at 1900, but just bogs and eventually picks back up, but still isnt reaching the 4200-4600 WOT the manual says...

I know it will do it, like I said in the OP, the first couple runs after I bought it, it would run excellent and about 42-4300 at WOT...

now sticks around 38-4000....

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Also, any link to what a dwell meter is? does it look just like a multimeter?

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

tshaw84 said:

would the points being off cause a dead spot in accelerating? everything I have done so far seemed to help a little,

Click to expand...

As a dear friend of mine says, "Everything has something to do with everything."
I don't know if it will solve your immediate problem, but a full tune up is always helpful. Be sure to look at the sticky at the top of the page which describes in detail how to tune up an engine with a points ignition. In addition, be sure to check the total timing - maybe your advance weights in the distributor are binding.

tshaw84 said:

Also, any link to what a dwell meter is? does it look just like a multimeter?

Click to expand...

Google is your friend!
Having said that, yesterday someone posted a link showing a tool that combines it all into one tool: Timing light / dwell meter combo.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Right, I am still new to this, Ive done a full tune up already, but I used feeler gauges for points, I figured out what the dwell meter is, and I already have a timing light, so I dont really want to buy another one. Ive been reading through posts and the DIY guides on my lunch breaks for a while now, but I figured in the mean time I would post something and maybe get some input along the way. Those guides are very detailed and are taking quite a while to get through...

I will probably pick up a meter tonight, Ill just have to find on here how to use it lol.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

The meter will come with instructions, but if memory serves, you hook the red lead to the negative side of the coil and the black lead to a good ground. Start the engine and read the results. Note that if the dwell fluctuates it is an indication of worn distributor bushings.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

You also need to set the point dwell first, then reset your timing. Dwell affects timing.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Im still searching the guides, I havent found an area that discusses that yet, just saying to test the dwell...

Now I assume the point dwell is just setting your point gap with the dwell meter?

Another question...will setting the timing while on the muffs be different from setting the timing with the added pressure from sitting in the water?

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

tshaw84 said:

Now I assume the point dwell is just setting your point gap with the dwell meter?

Click to expand...

yes

tshaw84 said:

Another question...will setting the timing while on the muffs be different from setting the timing with the added pressure from sitting in the water?

Click to expand...

no

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Thanks, I should have posting something a long time ago....I am learnin alot today...haha

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

After setting the dwell and re-setting or at least checking the timing, be sure to check the total timing as well. That will tell you the condition of the advance mechanism in your dizzy.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

You are starting to speak some other foreign language now....lol

Never heard of Total Timing, nor dizzy.....?

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Dizzy - UK, OZ, NZ, and some other countries way of saying distributor.

Total advance timing - timing advances as rpm's increase. Here is a chart showing the timing advance vs rpm for your engine.

Re: 3.0L still cuts out after replacing almost everything all my searching has told m

Ok ok I understand...Makes sense...I didnt get a chance to get the dwell meter, hopefully tonight.