I have a new to me 2001 Mercury 200 HP EFI that will only run in the start position and dies off when returned to the run position. I have verified good spark and fuel on all cylinders while in the start position to the best of my ability. I could use some help troubleshooting to a solution. This is my first post to this forum. Any help is appreciated.
check for 12v on purple wire on terminal block just above switchboxes does your horn sound when you turn key to run from off /does fuel pump run at key on =no id be looking at key switch and or wiring
.................................................. ...the scariest thing in life is the unknown ...................................
No horn sound when key to run. With tan wire grounded from the horn still doesn’t sound. I believe the horn is bad. VST Fuel pump runs with key in run with pressure around 36 psi. The key switch has been replaced in trying to fix the issue. With key on i should have 12 VDC on the terminal block at all times? I will verify this after work today.
yep ,if its still oil injected gotta have that horn working
.................................................. ...the scariest thing in life is the unknown ...................................
Unplug the cannon-plug connector inside the engine cowling (keyswitch harness). Clean the MALE pins, and spread them slightly with an exacto knife. Reassemble, and lock the connector in the STB side electrical plate (with a tie-wrap holding it in) as it should be.
May also want to monitor the purple terminal's voltage while attempting to crank. It should have 12V+ power when key is ON, at the START position, and when the engine is running (or SUPPOSED to be running).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Cleaned and Spread pins. 13VDC+ on purple terminal while in run and crank. Still only runs while held in crank. 12vdc at all times weather in run or running in start and when returned to run.
remove the black with yellow strp wire on outside switchbox or both boxes see if its shorted to grnd /ohm meter with key in run position
.................................................. ...the scariest thing in life is the unknown ...................................
Removed black wire with yellow stripe. With key in run no continuity to ground. Reconnected. Connected spark light to coil 3. Monitored spark through the cycle. I have spark all the way until it dies when returned to the run position on all cylinders. Monitored Fuel pressure with key in run. Fuel pressure around 33 psi. Which i believe is below spec. Removed pressure regulator and held over bucket, key on, a lot of fuel coming out and only 33 psi. Thoughts?
Also. Should the rail hold pressure after the pump is off or does it normally bleed to 0. After i turn the pump is off my pressure is 0.
Since gauges vary, 33 psi isn't that concerning. Pressure dropping to nothing after key turns off... that's a problem. Does the regulator stop dumping promptly when key is turned off, or does it continue to spray and drool?
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
With the key off it promptly stops spraying fuel out.
You either have a fuel leak inside the fuel management (intake), the top-hat seal on the fuel pump is leaking/damaged, or the electric fuel pump's relief valve is failing.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Is there a seal kit or seal numbers you recommend to resolve this?
the pump is a fairly new pump from Quantum HFP-512
Gaaarrrrr.... Aftermarket stuff again.
The seal in included in a rather pricey "Connection Kit" (which may or may not still be available).
We keep that o-ring as an individual part- if you drop an email to our Parts Department (with serial number) we should be able to get you one. It fits the OEM pump perfectly, hopefully the aftermarket is precisely the same.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
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Upon disassembly for inspection. The upper print was split in half and the lower oring was swollen out of its sealing surface.
The lower o-ring doesn't really "seal" as much as it provides a buffer to prevent the pump from flopping around inside the VST.
That upper o-ring (top-hat seal) is why your pressure was dumping off. Needs to be FKM or Nitrile material and decent hardness so as to prevent deterioration.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Reputed the top hat seal with new oring. Verified good pressure and speak with no leaks. Still not running correctly. Ohmed injector solenoids. All checked at 1.5 ohms. 4 wire system. Red and single wire for each pair of injectors. Verified 0 ohms through wiring in harness to ECM. Cranked unit over and watched only the cylinder 1 and 2 injectors spray. Monitored with meter spoons. Only the top two injectors are getting command from the ECM to fire. Is my ECM toast?
Do you have spark on all six cylinders? If so, have you disconnected the ECU connector, checked the pins for corrosion, and reconnected it (ensuring the twist lock ring is fully locked)?
It is possible to test the Injector Driver Outputs using a DVA.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Harness good. Connection good. Spark on all six. Fluke 87 on duty cycle watch injector output. Nothing for 3456. Is there another method.
Read VOLTAGE with DVA on 3-4 and 5-6. Should APPROXIMATELY match 1-2.
If you have spark, good connections at ECU and thus good inputs: It's likely the fuel injector drivers are failing. Simon Performance Technologies does a good job with driver replacement (simonperftech.com).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
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