Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

ta400man

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Mar 22, 2006
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1987, Sunbird, Eurosport, 18ft, 165 hp, 3.7L, 224CI, Merc, Alpha One I/O, Straight 4<br /><br />I just purhased the boat, I was able to get the engine running before I purchased the boat.<br /><br />I brought the boat home and ran the motor again with no problem.<br /><br />Then I power washed the interior and performed a simple tune-up, now the motor will not run. I replaced the plug wires, plug (.035" gap), points (.022 gap, dwell 30), condenser. The boat will turn over and cough a little, make a little smoke and run for two seconds when I let off the starter. It almost seems like it wants to run when the starter is running, the exhaust is coming out, but i never can get the engine to run. The throttle lock out does not work so I can not start the motor with any throttle. I checked the spark and I have alot of spark, and the timing is around 8 degree TDC, (running on the starter). The plugs were a little wet from trying to start meaning I have gas in the motor, replaced the plugs and still no start. <br /><br />Spark, Gas, Air (removed air filter), Timing, Points OK, what else is there in the boat to make it run. <br /><br />Thanks in Advance,<br />Shawn <br /><br />Note: Compression is as follows,<br />Cylinder 1: 150<br />Cylinder 2: 155<br />Cylinder 3: 132<br />Cylinder 4: 128<br />I figured the compression is within 15%, I figured it was ok.
 

Don S

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

The throttle lock out does not work so I can not start the motor with any throttle.
Starting an out of adjustment 470 engine without throttle isn't gonna happen.<br />Remove the shift cable for now, or disconnect the throttle cable and use a remote starter switch and operate the throttle by hand.<br />But you WILL have to fix the shifter<br />Then pump the throttle and see how it strts with some gas in the system.
 

ta400man

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Mar 22, 2006
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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Thanks for the advice. IT seems that throttle lock button is stuck in and no matter what I do to the button, it never will cut the shifter cable out.<br /><br />What part will be my problem, will i have to replace the throttle arm assembly?<br /><br />Thanks Again,<br />Shawn
 

lilmandavis

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Mar 9, 2006
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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

did ya replace the wires one at a time?!? or rip em off all at once
 

Haut Medoc

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Yep, you sure you got the firing order right?<br />2 wires in the wrong spot will not help...1-3-4-2....JK
 

ta400man

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

I did pay attention to the firing order. I checked to make sure where #1 was on the rotor bye finding cylinder #1 thru the spark plug hole at the top. Then I followed the firing order on the intake and the intake also shows which cylinder is what number.<br /><br />I think I checked it like 10 times because I know how easy it is to mess up.<br /><br />Thanks,<br />Shawn
 

Haut Medoc

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

By spark plug hole you mean that you felt compression as the piston was nearing TDC, correct? & the rotor was pointing to the #1 terminal, correct?....JK
 

ta400man

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Correct, I set the crank in the position where piston number one was at the top. Then I checked to make sure the rotor was pointing to the wire for #1 plug in the cap.
 

ta400man

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

I am starting to wonder if there is another switch some where that I could be my problem. <br /><br />What manual do people suggest to purchase for details on a wiring system?<br /><br />Thanks.
 

Don S

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Did you check to see if you have spark?<br />How about voltage to the coil when cranking?
 

Don S

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Forgot to mention, you need Mercruiser service manual number 8. PN 90-44553.
 

ta400man

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Mar 22, 2006
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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

I checked for spark bye grounding the threads of the spark plug on the block. I saw a hole lot of spark. I don't believe the spark is my problem.
 

leibin81

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Apr 21, 2006
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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Can you get it to run on Engine starting fluid? It may be a fuel problem if you have spark. If it runs on starting fluid, then you might have bad fuel, or it isn't getting pumped to the carb. Also check the points. The gap may be set right, but possibly could be fried. On a previous boat, I got spark, but the engine wouldn't start. I wasn't getting enough spark.
 

Gary H NC

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Listen to Don S...unhook the throttle cable then pump some fuel to it.
 

MrBill

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Boat-forever:<br /><br />Don S is right-on...my 3.7 have never started without throttle, even after conversion to electronic ignition. It'll need throttle to pump some fuel, in severe cases a carb re-build may be necessary if the float and /or needle valve have become problematic.
 

Don S

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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

DO NOT use starting fluid. That is the worst thing you can do to a gas engine.
 

ta400man

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Mar 22, 2006
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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

I tried to mimic pumping the throttle by pouring gas directly into the carb. It did not start the motor any better. I am out of town fishing for walleye this weekend, so I will take the shifter off just like Don S recommended on Monday and let you know what I got.<br /><br />Thanks,<br />Shawn
 

ta400man

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Mar 22, 2006
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Re: Engine wants to start, but will not;, 3.7L, 4Cyl. Merc.

Well, I took DonS advise and I replaced the throttle control which allow me to give the engine throttle with out shifting the out drive.<br /><br />The Engine started in like 4 cranks with a little throttle. The engine would simply not start without a little throttle. <br /><br />This concept seems so easy, I can not believe that I missed it. I wanted to thank this forum for allowing someone from Alaska to help me.<br /><br />Thanks,<br />Shawn
 
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