Mercruiser 170 wont start. HELP PLEASE !!!!

[trjerald]

I have an 86 Wellcraft with a Mercruiser 224cid 170 HP engine. Wont start this spring. Replaced cap, rotor, plugs, and completely rebuilt carb inclusing new fuel filter and accelerator pump strainer. Pressing accelerator produces a good stream of gas into the carb. When I open the fuel fitting going into the carb I get a spray of fuel which tells me its getting fuel to the carb. It has spark and will start briefly on starter fluid so I presume its a fuel problem not electrical. Its as if its not getting enough fuel to start unless I use starter fluid or pump the accelerator. Then it starts briefly and chokes out. Could it be the fuel pump is working good enough to produce some pressure but its too low of pressure? Im at a loss here. The carb was really dirty when I went through it and required alot of cleaning. Now its like the Im not getting fuel out of the primary jets, only from the accelerator pump. HELP !!!

 

[Bondo]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

The carb was really dirty when I went through it and required alot of cleaning.

Ayuh,... Sounds like ya missed a spot,...

Try again, or Replace it...

 

[trjerald]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

Thats what I was wondering. I just cant think how it would be anything other then a carb problem, unless the fuel pressure is just too low.

 

[stonyloam]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

Does it fire only while the starter is turning? If so check the resistance (purple) wire from the choke to the coil +. Need about 8 volts to the coil + with the key on.

 

[trjerald]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

Good point. Never really thought about it that way. I will check that out tonight. Thanks!!

 

[Don S]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

Its as if its not getting enough fuel to start unless I use starter fluid or pump the accelerator. Then it starts briefly and chokes out.

First, STOP using that starting fluid before you destroy your engine.... Get it off your boat.
Is this boat new to you? Are you familiar with starting a carbed engine?
You do realize that starting a boat that has set for a while WILL require you to pump the throttle once, twice, maybe several times. You also need to have the throttle lever up to 1/4 to 1/2 throttle to get it running.

 

[trjerald]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

I have had the boat for 5 year and so I am familiar with its typical behavior when starting. But this spring it would not start at all, no matter what I did. Tried the normal pumping the throttle, and leaving it part open, etc, etc. None of the normal stuff is working now so having to dig in deeper. I have spent 20+ years restoring cars, racing circle track, etc so I frequently work on gas engines, but this thing has be stumped.

 

[Don S]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

When was the last full tuneup? All the gas in the world won't fire on a weak, wimpy, yellow spark from bad plugs, points, cap, rotor, wires, etc.

 

[trjerald]

Re: Mercruiser 170 wont start. HELP PLEASE !!!!

This spring replaced cap, rotor, plugs, wires. Gas was emptied out last fall so all gas is fresh. Didnt replace points this spring yet. Havent checked the timing since last summer. Based on another post, Im starting to wonder if its an ignition problem that it starts and then dies from no ignition after the starter is disengaged. Perhaps I was thinking it was dying because the primer fuel ran out, when in reality it was dying because the ignition stopped firing after the starter was no longer engaged.....