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briggs archer
briggs archer, Marine Mechanic
Category: Boat
Satisfied Customers: 375
Experience:  30 years professional marine mechanic=skilled in all phases of the marine service industry.
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2004 sea ray 5.7 mercruiser 350 mag crank no start. New plugs,

Customer Question

2004 sea ray 5.7 mercruiser 350 mag crank no start. New plugs, rotor, cap, IAC. Let it sit overnight fires up. Run for just a few mi Utes and won't restart.
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with?
All Mercurys are cataloged by serial number, do you have that number handy.
When it stalls the engine is missing either fuel pressure or spark where you need to start is by testing both spark and fuel pressure, and seeing which one it has and which one it does not. Are you able to do those two tests?
Customer: replied 2 years ago.
It has both spark and fuel. I used a good quality spark tester and hit it with starter fluid nothing. When it does start it idles and runs like a champ, no misses, no stalling. When it don't start it seems to be an air problem. I can take the throttle Plat out of the throttle body and it will fire and Rev way up I immediately shut it down and do this a couple of times, put the throttle plate back in and it will start..
Expert:  Jason replied 2 years ago.
What kind of spark tester to have? Does it have an adjustable gap on it that you can set to 7/16ths of an inch, or is it one of those neon type testers?
Customer: replied 2 years ago.
Ow001403 is the engine serial number. Spark tester is a plastic see through type one end goes to plug and the wire plugs to the other end, crank the motor and it lights up. The boat did this before I did the new plugs, IAC, cap and rotor, I work as a mechanic for the USPS and have seen the same thing with some of our postal trucks and the IAC usually corrects it. But not in this case with the bost.
Expert:  Jason replied 2 years ago.
Got the serial number. I don't suppose you have a scan tool, such a Diacom or Techmate.
Customer: replied 2 years ago.
BTW my name is***** don't have a scan tool.
Expert:  Jason replied 2 years ago.
Hey Mike. There is no way to do anything on this engine without a scan tool. You will have to take it in. Good luck!
Customer: replied 2 years ago.
What would you be looking for with the scan tool? And where does the scan tool plug in at?
Expert:  briggs archer replied 2 years ago.
The scan tool, preferably a computer that can read the values of the sensors on the engine. A professional will study these values and recognize a failing sensor. In addition to the values, it will show the faults generated by the engine computer when present. This scan tool is connected to a connector located on the port forward side of your engine. This scanner cannot however, tell you if you have spark, fuel and compression. Jason's advice is correct.

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