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rough running 200 hp 1996 mariner

M

mikemonte61

New member
Greetings all.
I continue to have a rough running, hard to idle 200 hp mariner 2 cycle fuel injected. It fires and runs rough when cold but after a few minutes it get hard to start with extremely low idle. Dies when I put it in gear. It seems to run ok once I get it up and running across the lake. I have recently ran it out of gas
Repairs/ parts I have replaced include:
1. 6 coil packs
2. switch blocks (2) Sierra
3. spark plugs
4. complete fuel line & cleaned the tank
5. Compression test: 3 @ 135, 3@130
6. primary fuel pump diaphragm(s)
7. The existing injection fuel pump has 23 lb, 20 second time-out with ignition on.
8. All cylinders a firing with bright white spark and are consistent.
9. I confirmed the fuel oil mix by color against a known 50:1 mix in identical glass jars. Quicksilver oil & non-ethanal 91 octane gas

I am now leaning towards a fuel inject regulator. Does anyone know how to test the regulator or is there something else I should be testing?
Thanks for your help.
 
OK. I read that 80 lbs was a good pressure somewhere. I will change the electric fuel pump in the injection body and let you know how it turns out. Thanks
 
A little research showed me that actually the fuel pressure was a consistent 35. The running voltage was 7.5 & 19. That seems really high for the charging system. The boat ran rough and smoked quite a bit and would not idle
 
Naa...you need 36+psi. Also check spark at idle running with timing light as sounds like you got a stator problem to one bank.
 
Ok
I will check the consistency of the spark while high idle. 1200 rpms. any lower and it will stall. Do you suggest I change the fuel pump anyway. I am not against changing to new parts. I keep a good log book of new parts.
 
I was able to check the spark and it appeared very weak. 1/16" arc on all cylinders. Shouldn't this spark be scary strong? I checked all cylinders and didn't get bit once.
Have I thanked you for your help? Thank you
 
I replaced 6 coil packs with new ones. What else would cause a weak spark. I am still concerned about the 19V & 7V reading I had on the fuel pump while the engine was running. Does this all point back to the rectifier? Could this 19V have impacted the new switch blocks?
 
That sounds like great advice. So if the voltage signal from the switch box is weak then the output of the coils will also be weak? I have ordered a new rectifier/regulator due to the high (19v) supply to the fuel pump ($30). It looks like the 16-19 amp stator is around $150 new. I may just change it and start anew with the ignition system.
 
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