Mercruiser 170 problem

[mlsontag]

I just purchased a 1986 Baja 180. Boat has a a Mercruiser 170 engine. Previous owner stated that boat had sat for two years. Last time he ran it he drove it for a few hours and turned boat off. Never would start again. He had previously had installed new plugs, cap wires and points. I purchased boat and put a new battery in and changed the oil. Also changed the lower unit oil. Boat was very low on fuel. Added 4 gallons and boat started right up. Took boat out today. Ran fine for about 1 hour and 45 minutes. Oil pressure stated out at close to 40. Later it dropped to 20lbs. The temperature stayed around 175. Ran the boat between 30 and 40 mph. On my way back to the dock the boat just died. Like it ran out of fuel. Boat turned over just fine but was extremely hard to restart. Finally restated but ran rough. Oil pressure when idling was near 0. When moving it was near 20. Still had a half tank of gas. Got back to trailer. Anybody have any idea where to start? Ignition problem? Oil pump? Thanks for your help.

 

[stonyloam]

Re: Mercruiser 170 problem

Could be fuel filters, and old gas. You have two, one on the bottom of the fuel pump, and one behind the big nut that holds the fuel line on. Since it is a 470, I would do a compression check and a cooling system pressure check (borrow the tools from Autozone) just to know a little about overall engine condition. What oil did you use, recommended is 40 wt or 25W 40 so if you used something lighter it may read a little low. Here is a link to the service manual: http://www.4shared.com/document/zTbCbkDD/Service_Manual_08.html Welcome to the 470 club:facepalm:LOL

 

[mlsontag]

Re: Mercruiser 170 problem

Thanks for the reply. Someone told me to run straight 30 oil. Since there is now cold weather starts he said that would be fine so thats what I went with. Did find on the oil cap where it recomends using 10w 30. The tag on the valve cover says SAE 30. Confussed on the 470. Thought that was the same motor I have with a Ford head. How do I know if I have that?

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 170 problem

There are many different models of the 470, depending on the year and options.

The 470 block was also used in the 170, 165 (3.7 Liter),
485 (4 barrel), 488 (4 barrel), 190 (4 barrel), and the 180 (3.7LX with 4 barrel).

All of the 470 and 3.7L versions used closed cooling systems.

 

[Beefer]

Re: Mercruiser 170 problem

Could be fuel filters, and old gas. You have two, one on the bottom of the fuel pump, and one behind the big nut that holds the fuel line on. Since it is a 470, I would do a compression check and a cooling system pressure check (borrow the tools from Autozone) just to know a little about overall engine condition. What oil did you use, recommended is 40 wt or 25W 40 so if you used something lighter it may read a little low. Here is a link to the service manual: http://www.4shared.com/document/zTbCbkDD/Service_Manual_08.html Welcome to the 470 club:facepalm:LOL

Along with the above mentioned filters, check the screen inside the fuel pick up in the fuel tank. Remove the pick up from the tank, and unscrew the top off the tube. Inside there is a screen. It may be clogged just enough to allow fuel through it, but then as you use it, it clogs completely. That was my problem last winter. Also, check the ball check valve, and replace or eliminate it.

 

[Beefer]

Re: Mercruiser 170 problem

I forgot to mention to make sure the fuel tank vent is unobstructed, and functioning fine.

 

[mlsontag]

Re: Mercruiser 170 problem

10 frustrating hours later this is what I found. Removed in line fuel filter before carburator. Filter had some sort of red material in it. Reminded me of gasket material that had deteriorated. Cleaned and put a new filter in. Then removed the fuel pump. Took the bottom off and found the same red material in it. There was a light blue cone shaped stone that I cleaned in solvent and put back together. Thought this would take care of my problem. Hooked up water and now engine wont start. Issue yesterday was it was like it ran out of fuel but got it restarted. Engine would turn over today but not start. Traced some problems down and found no power coming out of coil. Replaced coil but still no power coming out. Using a test light it now shows power on the positive side but nothing coming out. Could it be a bad ground or coil wire bad?

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 170 problem

Could be bad tach or shorted tach wire to ground which is on (-) of coil. or the condenser under the distributor cap.

 

[Beefer]

Re: Mercruiser 170 problem

10 frustrating hours later this is what I found. Removed in line fuel filter before carburator. Filter had some sort of red material in it. Reminded me of gasket material that had deteriorated. Cleaned and put a new filter in. Then removed the fuel pump. Took the bottom off and found the same red material in it. There was a light blue cone shaped stone that I cleaned in solvent and put back together. Thought this would take care of my problem. Hooked up water and now engine wont start. Issue yesterday was it was like it ran out of fuel but got it restarted. Engine would turn over today but not start. Traced some problems down and found no power coming out of coil. Replaced coil but still no power coming out. Using a test light it now shows power on the positive side but nothing coming out. Could it be a bad ground or coil wire bad?

I'll guess the most common; ground wire.

The red stuff in the filters kind of sounds like crud in your tank that is clogging the delivery system. If you can, siphon out some fuel from the very bottom of the tank into a glass jar. Look for sand-like reddish particles. That's the shellac on the walls of the tank being cleaned off by ethanol. You can also check for the particles in the bowl of your FWS. If there is some, take apart your fuel pick-up tube, clean out the screen (or remove it), and change every filter. Make yourself a fuel polishing system, and cycle your fuel through it. Get a cheap manual pump, a couple feet of fuel line, and an auto fuel filter (I added a small clear inline filter so I could see what was being cleaned out), and just pump it out, through the filter(s), and back into the tank. Eventually you'll get all or enough of it out so it doesn't clog the filters on the boat. They'll just filter them out over time.

Last year I had a very similar situation. I could run it for sometimes up to an hour without a problem, sometimes only a few minutes. Always ran at idle speed. What was happening was gunk inside the tank was being collected on the screen, and as the need for more fuel (higher speed) happened, the screen would get enough crap on it that it wouldn't be able to supply the system. Took me 5 months to figure it out.