Merc 200 XRi problems

**loop** · 10-02-2016, 01:27 PM

ok im totally new to this Merc stuff so would appreciate any help i can get
Motor is a 1995 200 XRi
ser#OG282293
Oil pump deleted 50 to 1 premix

Yesterday it was running great,then while cruising at about 3500rpm it started losing power. I stopped immediately and it came back to a nice steady idle. tried to get on plane and it would fall on its face but not die,then go back to a good idle. After a couple of tries it would get on and hold plane but motor wouldnt rev at all so i just shut it down. Since it would still idle i decide just to idle to the ramp about a mile away. After a couple of minutes of that,it died and wouldnt start. There were no warning beeps but noticed that fuel pump was not running with key turned on

Today.
jumped neg terminal on fuel pump and it runs right around 40psi
compression: All 6 were 110-115 psi
Spark:Starboard good spark
Port weak/intermittent at first and now no spark

motor will not even attempt to start or run even with 3 cyls and fuel pump running

Trying to make heads or tails of CDI troubleshooting guide (not my strongest area so please bear with me)
OHM readings per CDI for blue and blue/white wire should be 2100-2500. mine are zero or completely open for both
" " " " for red and red/white wire should be 28-32. mine are 112 for both

hopefully someone can point me in the right direction
Thanks

**DOUBLE J** · 10-02-2016, 03:32 PM

It's a switch box going out There is 2 on the motor and one is going out. Mine did same thing (intermittent @ first than finally just wouldn't crank). You can tell cause you shouldn't have any fire on on one side of motor.

**loop** · 10-02-2016, 04:44 PM

Thanks
would that cause the fuel pump issue also?
definitely dead on 2,4,and 6

**DOUBLE J** · 10-02-2016, 04:54 PM

Fix the firing problem first. Then if fuel pump is intermittent than it's the fuel pump .Basically computer turns pump off and on as needed. If it acting up there is a way to hot wire pump where the pump comes on automatically when turn key on. The only disadvantage of doing that is that if you forget to turn key off you will be drawing on battery. Really not a big deal.

**loop** · 10-02-2016, 06:26 PM

swapped the switchboxes side-to-side and the problem followed the bad box so I will be ordering new ones tonight.
fuel pump still didnt come on so looks like i'll be hot wiring it
Told myself i didnt even want to learn about the Merc since my plan was to sell it and put an OMC on the boat. But I'll admit its been interesting so far and it really does run nice.
Thanks for your help

**loop** · 10-08-2016, 01:35 PM

Switchboxes replaced. I now have strong spark on both banks....and it STILL wont even try to start.
Sprayed a little fuel into cylinders via the spark plug holes and it fired up immediately for just a second
Any Thoughts?

**Capt.Insane-o** · 10-08-2016, 01:48 PM

You have the wires that trigger the ecu on the right terminals on the switch box?

**loop** · 10-08-2016, 02:23 PM

best i can tell
I dont know exactly which wires those would be but I put every wire right back where they were supposed to be according to the colors marked on the switchboxes

**loop** · 10-08-2016, 02:55 PM

double checked and yes the green,green/wht, and green/red wires on the outer box are connected properly

**flabum1017** · 10-08-2016, 03:01 PM

Have you checked the fuses on the motor?

**loop** · 10-08-2016, 03:15 PM

Ive only seen one so far on the red/ purple wire

**DOUBLE J** · 10-08-2016, 06:07 PM

Put your hand on fuel pump and have someone turn key on and see if you feel and hear the pump turn on.

**loop** · 10-08-2016, 07:51 PM

It won't come on unless I jump the negative terminal. Then the pump runs at about 40 psi but motor still wont start

**flabum1017** · 10-08-2016, 08:57 PM

I need to get my book to help you further, but there are others here that know it off the top of their heads...... seems to me that if the pump isn't coming on thru the ecu, then the injectors won't fire either......