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Mercury Mericrusier 5.7L Carbureted RPM Jump Then Stall

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macecanuck

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I have a 2002 Crownline BR230 with a 5.7L carbureted Mercury Mericrusier with 400 hrs. Drove it all day until suddenly it would surge in rpms then drop and be fine then a few seconds later do it again. Backing off the throttle then eventually it would stall when trying again and again until it wouldn't start at all. Fuel pump, fuel filter, fuel lines, fuel all good. Clean air filter, good batteries, no vapor lock. Can anyone tell me what the issue is.
 
Do you have spark ? By fuel is good when you pump throttle does fuel shoot from Accelerator pump into throttle bores?
 
Thanks for the replies.
  1. Yes I have spark and fuel is present, plus you can smell the gas. Stater valve when pressed fuel comes out.
  2. I had the boat in the shop for diagnostics the next day, of course the boat started? They couldn't test under load.
  3. The shop flushed the fuel lines, replaced one line, and replaced the water/fuel filter.
 
macecanuck said:
Thanks for the replies.
  1. Yes I have spark and fuel is present, plus you can smell the gas. Stater valve when pressed fuel comes out.
  2. I had the boat in the shop for diagnostics the next day, of course the boat started? They couldn't test under load.
  3. The shop flushed the fuel lines, replaced one line, and replaced the water/fuel filter.
Click to expand...
If spark and fuel is present you should at least get a cough . Has timing been checked? Do you have compression issue?
macecanuck said:
Where do I find the engine serial no.?
Click to expand...


Stater Valve ? do you mean accelerator pump ? If you smell fuel it might be flooded if you open throttle wide will it eventually start? This can help clear flooding.

Did they replace the fuel lines due to contamination ? if so carb may need a rebuild. Spark jumps a good 3/8" gap? Fuel, spark, compression must be missing one

Serial number is on the flame arrestor cover and also on a tag riveted above the starter. Additionally have seen it in the paperwork that was in with original owners manual etc from the dealer. At least with the 2 sea ray I have had it looked liek the documentation that came with the power pack from Mercruiser got included with the owners packet of paper.
 
Well I apologize. After looking closer at things and finding the stock flame arrestor cover the details I provided were wrong. I am attaching a photo with all information
 

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377 CID (6.2L), plugs MR43LTS gap .045, timing 8* BTDC, MEFI-3 and TBV ignition

Put a fuel pressure gauge on Schrader valve, you should get 43 psi with key ON, engine Off (KOEO)

The good thing is you have a MEFI-3 ECM so if it has codes they can be found using a multimeter with a tone function or using a 12V resistor LED

Look at the pickup module under the distributor cap. See if it looks rusty, also look for how many wires are attached to pickup. If just 2 wires, I would suggest changing it to new style with 3 wires. The older ones have issues with loosing ground and was the reason Merc changed the design
 
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