3.0 mercruiser issue

[Steve.e]

Hi all, I have an issue with my 3.0 130hp mercruiser. Motor out to fish and runs ok out, troll for 3 to 4 hrs and it dies. I can immediately start back up and go 30 to 50 yrds at ~8mph and then it dies again. Try to go faster and it dies immediately. Can do this all the way in to get back + using my kicker. Checked fuel system to pump for crude, replaced pump filter, installed inline water separater, replaced plugs. Happened again pretty much identical to first instance. Seems like something might be getting hot like the coil maybe? Maybe the pump has a diaphram that is failing? Carburetor rebuild? Almost the same as a lawn mower that needs the float valve cleaned out. By the way the coil is almost impossible to find and I assume expensive since no longer available, and ignition control module is 760-820 bucks-yikes. this has a digital elect ignition. can it be converted to a standard elect ignition?  Any help will be appreciated greatly.

Edited July 15, 2022 by Steve-e

[Bozeman Bob]

Sounds like your running out of gas . When's the last time the carb got rebuilt / cleaned / gone through ?. Should be a off the shelf car coil unless it's for something like a Petronix system. If I had electric issues and it needed some control module I would buy a new electronic distributor for less than 150.00 online and run it direct to the coil before I dropped any stupid money on " there " module . 

[Steve.e]

Had the boat for 6yrs, no carb work by me. this issue has happened 3xs exactly the same. Does act like it's running out of gas but over 1/2 tank each time. I can run it the next day in the driveway and it fires up and runs, just did again just now , ran perfect. I just cleaned the large round connector above the ign coil and wires, they were corroded last year and I cleaned and put diaelectric grease on pins. The grease looked like it migrated a little between pins  so i just cleaned with alcohol and blew all the grease out and wiped. Did that first before running just now, ran great but has before after getting home. Might try again tomorrow, see what happens.

[Steve.e]

Just asked tom Barbera if he rebuilt the carb and said he did 6 yrs ago when he had the boat for a few weeks. I bought it from him. The boat is not heavily used, limited to lake O wave action. 

[Dusty]

How old is it?  Sounds like a points/condenser issue. I’ve got the same engine circa 1988 and have found all aftermarket ignition products to be inferior in size and quality. Watch the cap and rotor for correct contact and file/burnish your points for a square contact. 

[Bozeman Bob]

When I say "running out of gas " I don't mean how much gas is in your tank. The passageways and or bowl float  check valve are not 100%. When the float etc isn't working your motor will run on the trickle of gas your getting . Give it some throttle and it's now starving for gas. Usually if the points are bad , if you don't have a electronic ignition , it will miss , run rough , but not the same symptoms as your describing . And running it on muffs in the driveway is not the same as being on the lake . You are not putting any sort of load on the engine , so a quick rev is going to use a shot glass of fuel , do that on the water in gear and you have used a cup , bit of a difference in the fuel demand .

Edited July 16, 2022 by Bozeman Bob

[Steve.e]

 Maybe the carb does need rebuilding again, I'll try to find somebody to do it, I never have. Thinking of replacing the pump also incase of an internal issue, but seems to be OK, there is pressure in the lines when I pop one off the separator.

[Traveling Circus]

Accelerator pump? I previously owned a boat with that motor, and the a-pump was susceptible to corrosion. I had similar symptoms, but I don't think it would have been possible to motor out to fish....... It was bogging down any time applying increasing throttle.

[Bozeman Bob]

The fuel pump is working , otherwise it wouldn't start or run . They are either good or bad , no in between . If it was me I would buy a new or rebuilt one before having mine done local . Maybe try  customrebuiltcarbs.com   which I have used 6 times over the last 4 years on various boats .  Jegs is another option .

 

Edited July 16, 2022 by Bozeman Bob

[Steve.e]

Dusty it has an electronic ignition, some kind of digital type only used for a couple yrs. With a control module also. Bozeman, thanks for the info, might get another carb , get back on the water quicker. 

Edited July 17, 2022 by Steve.e

[sherman brown]

if it was electrical i don't think it would start back up and run. if an electrical item goes bad it's usually all or nothing.

 

what I'm thinking is if it has a fuel water separator that hasn't been changed lately it could very easily be stopped up.

[privatedata]

45 years of technical service work here , I'd cover the maintenance items of the fuel system first . Fuel Filter replacement , Carb inspection , clean , repair . Fuel Quality is often overlooked 

[Captain Laxton]

If you have an electronic fuel pump I would recommend replacing that first. The problem sounds to me like something is getting hot and failing. It could be the ignition module also. Almost can't be the coil because it starts right back up without having to wait for it to cool down.

[bruce lindsley]

I had the same thing happen to me , found out that the problem was the fuel pump , The inside of the Mercruiser fuel pumps are painted or coated with something that is black in color , Which starts to come off and screw up the fuel system because of the crappy quality of gas we have these days , And it doesn't matter if you use Non Etheonal or Etheonal , I replaced the fuel pump om mine and that was the end of the problem , It's ran perfect ever since .

 

[Steve.e]

Bruce, would your boat stall and then start right back up and stall again when accelerating? Did it happen during an outing with it seeming ok for awhile then act up? What kind of pump did you replace it with, OEM or another brand?

[Steve.e]

Privatedata, I drained tank, checked fuel lines to pump, replaced fuel pump filter and installed a water separator all in last 3 weeks. Heath, could be the module, Tom at east fork said the same. Hopefully not. They are NLA, hard to find and mucho expensive, I believe the coil is part of the module. Pump is mechanical.

[bruce lindsley]

Hi Steve , yes it would excellerate then start booging down , then stall , then it would start back up and do it again , what was happening is the paint or coating inside the pump wouls break up it tiny particles and the when it gets in the carb it would cowagulate and plug up the small jets and orffices , An easy way to see if this is happening is to take your fuel pump off it should have small screws around the casting that attaches the upper part of the pump to the lower part , it should be an indexable fuel pump , take a few pictures of it so you put it back together the same way , just in case it is not your pump , you will be able to tell if the painted coating is coming off ass soon as you open up the pump ., I tryed everything before I found out what the problem was . This happened 3 years ago and I haven't had a single fuel problem since I replaced the pump , I got the new pump from boats.net 

 

[Steve.e]

Bruce did you have to take apart the carb and clean out the ports etc.

[bruce lindsley]

Yes I did 

 

[SamonSez]

Steve, if you have the carb looked at by a professional, at least you can rule that out. I had similar problems as you.  The engine would start very easily but with the engine warmed up and running under load it would choke and die. It was the carb. Obviously I can't say for sure that your problem is the same but the behavior of my engine was the same.  

 

I highly recommend Tom Toal in Ontario, NY for all carb work. Hopefully he is still taking on new work. He is the GM engineer that worked for GM for something like 40-50 years. He is the engineer that actually designed the carbs for GM. He knows everything there is to know about carbs. Quick turn around time, very good pricing, and all of the stories come for free (and he has many).

 

Tom Toal

1232 Paddy Lane

Ontario, NY 14519

585-230-9616

 

Best of luck to you.

[Steve.e]

SamonSez, thanks for that info, I will definitely give him a call, can't go wrong with his experience!

[piscataquis]

Let me say from past practice. I am no means a professional and I will never say I am. I am an "barn yard high risk mechanic". Now with all that out there and no great expectations from my infromation I will continue.

 

Yes what everyone has said is spot on. get everything cleaned up and continue with preventive care.

 

Ok. What caused me issues. Check your carb for little black balls. We went backawrds in the process and found this last. I found that our fuel line was breaking down. Even the filler hose. This hose break down was causing these 'black balls of rubber" to clog the carbs. We found this after the first carb cleaning. So we had to pull things appart again after the fuel lines were replaced. We even found this in the tank. Figuring it came from the filler line. We did this 4 years ago and things have been good since. Probably will have issues next time in it now im bragging a little. Just a I wanted to toss out there. I hope yours is just a simple cleaning. best of luck 

[Steve.e]

I want to replace the fuel pump also but don't want a mercury one if the internal coating is a problem according to Bruce's post. Any recommendations for a replacement aftermarket pump?

[Jim's Jewel]

I don't have your same engine, but several years ago I had similar problem with Merc 7.4L engine.   It would start right up & run for a while.   Would die when accelerating or under heavy load, would run OK if I pulled it back to an idle.   Mine has mechanical belt driven fuel pump.  GM eliminated block opening for fuel pump because of fuel in injection in 1993 or 94.   Merc kept carburetor for a couple of more years & used belt & cam to power it.   Replaced the mechanical pump & all problems are gone!!   I was told they have 2 diaphragms inside & they get stiff from lack of use in the winter & ethanol in fuel.  

Found the pump on https://marinepartssource.com/   They carry a lot of Merc parts at fairly reasonable prices.   

[Tail Spin]

I had same engine similar problem. Ended up being the carburetor bowl had water/ethanol in it and float will not drop all the way to allow gas in.
 

 I see you checked fuel system but check carb bowl and float height settings while your in there. 

 

It go so bad for me it would start and run perfect but if you stepped on the starboard gunnel making the boat lean at all while idling perfect at Dock it would stall instantly.