1979 175hp Merc cold start fire problem

[tsto72]

I've had this boat for about 4yrs now. When I first bought it I was told by the previous owner that the engine was whipped. Needless to say after a reasonable repair bill the motor returned in working condition. I was told by the marina that they put a "heavy" mix in since the boat hadn't been run in a while. Unfortunately it was at the end of the season & I only had 1 chance to try her out. I had to prime the plugs with starter fluid (at the time I didn't think this was a problem due to the heavy mix) & she started right up. The following year in the spring I had to do the same thing (use fluid) & to this day the boat will not cold start without using starting fluid. It won't even pop, just crank. The odd thing is after running the boat for 2+ mins I can shut it off & troll for hours & it will start right up without using the fluid. I have looked at the plugs & they seem clean & not fouled (I have also changed them). I have adjusted my mix several times & still no help on the cold start. Anyone have any ideas as to why the boat won't "pop" during a cold start?

 

[Barnacle_Bill]

Re: 1979 175hp Merc cold start fire problem

STOP using starting fluid! There is no lube in that stuff. Put some pre-mix in a spray bottle and use that. Check you choke/enrichner and be sure it is operating correctly.

 

[sbva]

Re: 1979 175hp Merc cold start fire problem

Will it cold start on the ears?<br /><br />I have same problem on that initial start but found that if I back the trailer up just enough to submerge the lower unit/water vents, she starts right up. Warm it up a bit and launch, no problems the rest of the day. <br />If I try that initial start fully submerged my battery dies trying<br /><br />Just likes to test the water with its toe first I guess

 

[KCLOST]

Re: 1979 175hp Merc cold start fire problem

tsto,<br /><br />I thought I would pop in and mention something you "need" to do when starting that motor.. You didn't mention doing it so here it goes.<br /><br />You must squeeze "prime" the fuel bulb until firm. This may take up to 10 squeezes for the fuel to make it up to the pump. If you have good spark at cold start and no fire, you're just not getting fuel... So hopefully that is all you need to do. <br /><br />Let us know.

 

[tsto72]

Re: 1979 175hp Merc cold start fire problem

After the long story I forgot to mention that I am squeezing the bulb till it's firm (sorry). The choke is engaging as well. I'm smelling fuel & can see the bottom of the carb cover is moist. I will test each plug for spark but don't think this will be the problem since it starts after I have had it running. As I said it just cranks & doesn't even attempt to fire when cold. Thanks for the advice on stearing away from using starter fluid I will try the spray bottle trick.

 

[ROTTYRAS]

Re: 1979 175hp Merc cold start fire problem

MY BOAT STARTS UP BUT ONLY FIREER TOP CYL REED MINE ROTTYRAS

 

[KCLOST]

Re: 1979 175hp Merc cold start fire problem

Are you advancing the throttle to the fast idle position during cold start?<br /><br />Have you checked the compression on all the cylinders.. If not, do so and report the readings to us. This is very important, and could be the cause!<br /><br />Check the spark with a spark gap tester, this will ensure that the spark will still reach ground and prevent damage to the switchboxes and stuff. Start with a gap of 1/4". As you mentioned, you might be ok but it's good to check.<br /><br />You might also try this just to ease my mind on the fuel issue. While you are trying to cold start the motor, have a friend squeeze the bulb while it is cranking. See if that makes a difference. I want to make sure that you are getting fuel to the pump. The bottom of the carb cover (air-box) will always be wet by the way.

 

[tsto72]

Re: 1979 175hp Merc cold start fire problem

Spark @ .25" is good @ every plug. Compression is as follows 1 & 3 125, 2, 4, & 5 120, 6 is at 118. Pumped the bulb while turning the key & still no difference. I have also advanced the throttle form a little to full & nothing.

 

[tsto72]

Re: 1979 175hp Merc cold start fire problem

From the readings above things seem to be fine any suggestions?

 

[KCLOST]

Re: 1979 175hp Merc cold start fire problem

Well, that's good news on the spark and compression... But what that tells me is that you are not getting fuel!<br /><br />First, What plugs are you using?<br />Is the fuel tank venting properly?<br />Is the battery fully charged? <br />Fuel filter and water separator clean?<br />No kinks in the fuel lines (or leaks)?<br />Carbs? Have they been cleaned lately, they might be due...<br />Check all lines on the carbs...<br />Fuel new or old? (I assume new)<br />There is a check valve somewhere on the fuel line to prevent fuel from going back into the tank. That could be the culprit... <br /><br />It's tough to diagnose, but keep at it... And let us know..

 

[robalofish]

Re: 1979 175hp Merc cold start fire problem

Just a thought, you may want to double check that the choke/enrichment valve is truly dumping gas into the lower carbs by removing the hoses from the valve and checking that gas does flow out of the top carb and to the valve. Next check that the gas can get to the lower carbs try priming thru the hose.<br /><br />I'm assuming you have an enrichment valve and not a butterfly type choke here.<br /><br />Also in your starting procedure are you holding the choke button (key in on mine) while you are starting, as well as a full 10 seconds before you crank it?

 

[KCLOST]

Re: 1979 175hp Merc cold start fire problem

You've got a good engine with your readings...<br /><br />We will get it...<br /><br />If you have the time, now check the spark at 3/8"..

 

[tsto72]

Re: 1979 175hp Merc cold start fire problem

THANKS! I'll be pluging away at the list this weekend. I am fairly green at it & have a repair book coming. A suggestion that my uncle has, whose somewhat of a boat guy is to bypass the tank & pump by connecting a container straight the the fuel lines heading into the carbs. Maintaining a height above the engine. Should I try this first or work on the items on the list? The plugs are wet so I know they are all getting gas. Your right I still have the old gas in it but last year with new plugs & new gas had the same problem. I'll be draining the tank & using new gas & install new plugs for the container idea. I'm using the choke for the 10+ seconds with a hard prim bulb. Just spins, no fire. I'll try the spark test at 3/8". Just trying to save another repair bill & learn a few things Thanks for your patience!!

 

[KCLOST]

Re: 1979 175hp Merc cold start fire problem

When you prime (squeeze) the fuel bulb, do you see fuel entering into the water separator. It's a transparent filter that should be mounted on the starboard front side of the engine.. Follow the fuel line to it...