1992 mercury 200efi losing power

[5at38off]

Im a newbe here but been browsing the site for years. nice forums.
I have a 1992 200EFI on a champion bass boat. Cant seem to find my power problem. engine starts great and hole shot is normal. it will tach up and reach 60mph real easy. as im going along I loose power and the engine flutters. from there it backs down around 45mph. I can back off the gas and it will smooth out and kinda cruise. then if I give it gas the engine will really sputter and you can see the engine knocking back and fourth till I back off the gas again. If I stop sit for a minute the whole process starts again. it will hole shot great then loose power as I go. anyone seen this problem..

 

[blackdc]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

same problem with a 97 200 merc loose power at full throttle and shut down to idle then after a short period it will take off again. no problem a half throttle. mer. mech. can,t find the problem

 

[Faztbullet]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

Disconnect the rectifiers and retest.

 

[5at38off]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

If I understand right a rectifier is for the alternator, what will disconnecting it show in a test?

 

[stewmax]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

Check back flow check ball in fuel tank pic up. It could be stuck. Can you see
the primer ball going flat when it drops power? I went crazy with the same thing sometime back.some times it is the little things we over look.
Good luck.
Stew

 

[5at38off]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

I have noticed the primer ball is staying firm, it is new.
Im not at home with the engine but the rectifier has 5or6 wires. which wires do you disconnect?

 

[Faztbullet]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

Disconect the yellow wires, a bad rectifier can overheat/spike a stator while running.

 

[sschefer]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

I'll SWAG this one. Bad thermostat(s) opening way to early and causing cold leanout. Happened to a buddy of mine. Same symptoms. Doesn't happen until your up and running for a bit becasue the poppet valve is open and it's supposed to provide all the cooling you need. But, if the thermostat does open, your engine temp goes way down and the combination of a lot of fuel and cold cylinders makes it hard to support combustion.

15.00 each to replace the thermostats and a half hour of work. Or, you can go through the process of testing yours in a heated cup of water and a thermometer. Change them annually when you change your impeller.

 

[Faztbullet]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

I disagree on that as the t-stats are not functioning when poppet valve opens. See water flow chart...

 

[Dukedog]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

I agree. T=stats won't cause this. Ask your mech. if he checked/changed or removed tha tiny cone shaped filter thats in tha U shaped fuel hose between tha pump and vst tank. This little pita gets over looked a lot.
Also tha round filter above tha pump.
Needle and seat, float setting in tha vst.
Pluse (mechanical) pump................

blackdc, Yours won't have those filters. It has one in tha vst attached to tha bottom of tha pump.................

 

[madgadget]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

My 220EFI was doing the same. I checked all filters, changed fuel pump (high pressure) etc.. not had a chance to test it since due to weather. But watching this thread with interest I may learn something.

I am going to go out with a fuel pressure regulator on next time to see if rail pressure drops, and monitor ecu supply voltage. That may reveal something I hope. Or ill hook up my DVM to the injector supply and see if that is going a bit nuts.

So many things to look at on an EFI engine.

 

[sschefer]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

I agree. T=stats won't cause this. Ask your mech. if he checked/changed or removed tha tiny cone shaped filter thats in tha U shaped fuel hose between tha pump and vst tank. This little pita gets over looked a lot.
Also tha round filter above tha pump.
Needle and seat, float setting in tha vst.
Pluse (mechanical) pump................

blackdc, Yours won't have those filters. It has one in tha vst attached to tha bottom of tha pump.................

Ever heard of cold lean out... probably not. You might want to do a search on it on one of the more technical boards.

 

[Faztbullet]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

Post from BBC ....
"WOT water temps will often be SUBSTANTIALLY lower than "thermostat temperature".

This is simply because the Poppet Valve controls water pressure at higher RPM's... and once the Poppet Valve has opened, the thermostats are essentially "non-functional".

Don Weed @European Marine 864-421-0444
(Mercury Master Technician)- Mercury Outboards, Mercury Racing and Mercruiser (Certified Tech) Sterndrives, Greenville, SC

Never heard of cold lean out and been doing this for 30+ years, and its not on ScreamandCry,BYB,BBC,BWB that I can find

 

[Dukedog]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

I know exactly what it is supposed ta be. Never heard of it asssociated with these motors anyway. Cold seize, sure. but results are pretty quick. If this was tha case (very unlikely) I think tha motor would only stumble just a bit maybe but would recover as tha temp evened out which wouldn't be long at 6 grand. With tha efi its gonna detect any drastic temp change and adjust to compensate (temp sensor, port head) usually goin' ta full rich. Donno? Just maybe you've stumbled on ta something I've never seen or heard of till now........................

 

[Dukedog]

Re: 1992 mercury 200efi loosing power

Re: 1992 mercury 200efi loosing power

Post from BBC ....
"WOT water temps will often be SUBSTANTIALLY lower than "thermostat temperature".

This is simply because the Poppet Valve controls water pressure at higher RPM's... and once the Poppet Valve has opened, the thermostats are essentially "non-functional".

Don Weed @European Marine 864-421-0444
(Mercury Master Technician)- Mercury Outboards, Mercury Racing and Mercruiser (Certified Tech) Sterndrives, Greenville, SC

Never heard of cold lean out and been doing this for 30+ years, and its not on ScreamandCry,BYB,BBC,BWB that I can find

Case at rest! Now go take your meds.................

 

[5at38off]

Re: 1992 mercury 200efi losing power

well we have over a foot of snow on the ground now and lakes are freezing over so I dont know when I will get to do another water test. I did take off the small bullet looking filter on the right side looking at the engine. I blew some light air through it to see if it was clogged and air was seeping out from the side. looks like where the plastic is molded together. I will have to get a new one. The large filter on the left side I dumped it out and reinstalled it.. I will do the rectifier test when I get back on the water.