200xri limited to 3500 rpm

[bill200xri]

I have a '94 200 xri, S/N 0G060988, with a problem that prevents from accelerating over 3500 rpm. I have no problem accellerating out of the hole, and can run on plane at 3000 rpm with no issue. I ran thru the Merc manual to troubleshoot. Fuel pump puts out 39 psi, but I did not check it at speed. Should I? Anyway, the fuel system troubleshoot concluded that it was an electrical problem, although I did not do in-line pressure checks...just checked the high pressure pump at the zerc fittting.
Resistence checks on all component checks good. DVA check on coil input voltage good. Spark test appeared good, but not sure with the visual test using spark gap test tool. Spark could be weak. Could be a coil or two? If I had a bad coil, would I know it at lower speeds? Timing at idle is 2-degree ATDC, timing at 3000 rpm 18-degrees BTDC. Timing is steady at all speeds up to 3500 rpm, where it starts to move around as the engine speed changes (revs and drops, and if I give it full throttle, it chugs). When the speed revs to 4000 rpm for a split second, the timing was ~22-degrees BTDC. Anyway, the manual troubleshoot step indicated that I should now look at the fuel system (back to square 1).
Can anyone give me tips on what to check next?

Thanks,

Bill

 

[bill200xri]

Re: 200xri limited to 3500 rpm

I read a few FAQs, about rectifiers and stators. I'll recheck those parts.

Also read about spark gaps. Should I check spark with all plugs removed to get max cranking rpm? For this motor, should I set gap at 7/16"?

Another note, I had a similar problem a few years ago, that turned out to be a bad stator. It was replaced and all was good for a year....and hear I am (been messing with it for about 8 months on and off). That repair cost me $3000 with a bunch of time wasted on fuel system checks, boat test runs, etc. Thought I'd tackle this one.

Anyone out there?

 

[Faztbullet]

Re: 200xri limited to 3500 rpm

Unplug the rectifiers and retest, if engine act like its running to rich check linkage on air butteryfly to see if both sets are opening.

 

[bill200xri]

Re: 200xri limited to 3500 rpm

I had forgotten about this post! Thanks for the reply.

After doing some more reading, I thought I learned that the rectifiers are contained within the switch boxes. If not, can you point me to where they're located? I cannot locate them on wiring schematic.

 

[Faztbullet]

Re: 200xri limited to 3500 rpm

They are mounted under the coil mounting plate , there will be 2 of them. Just unplug the yellow wires from the quick connectors.

 

[bill200xri]

Re: 200xri limited to 3500 rpm

I water tested the motor today, and think that my problem is fuel related. Please read the tests I did and let me know if I'm on the right track. While running, I measured fuel pressure upstream of injectors, and it measures a steady 34 psi up to about 3400 rpm. Then it falls off when I get to 3500 rpm, which is when the motor chugging starts. With the throttle pegged at WOT, fuel pressure drops to 25 psi. The butterfly valves are wide open (at least the lower one, that I can see). DVA voltage to the coils remains steady at ~ 200 volts during the chugging, and is consitent on all cyclinder coils. Squeezing the fuel line primer ball does not help. Does the DVA voltage results eliminate the stator and switch boxes? Any suggestions on what to test next, or your opinion on what is the problem? I'm looking at either a check valve or the high pressure pump.

Bill

 

[bill200xri]

Re: 200xri limited to 3500 rpm

Ran more on-water tests this weekend, and was able to sustain 4000 rpm without chugging.

Would not exceed 4000 rpm without chugging.
Note that this problem initially was observed to chug at 3000 rpm after having sat for a while without being run, then increased to 3500 rpm, and now occurs at ~ 4000 rpm. I plan to clean out the fuel supply lines and filters, and re-test. Does that sound logical, after reviewing the data below? Also, does detonation sensor check show I have a faulty sensor? The detonation module was replaced Apr 2007 (broken from handling damage), so I would hope it's still good.

Sorry for the long post, but now you know all that I know!


Summary of test results:

Mechanical:

Compression- cyl 1- 115 psi, cyl 2- 120 psi, cyl 3- 115 psi, cyl 4, 115 psi, cyl 5- 115 psi, cyl 6- 120 psi

Fuel system:

Pre-start manifold pressure- 36 psi. Drops to 32 psi when pump shuts off, and bleeds to 25 psi over ~ 5 minutes, if engine is not started. Does this indicate a check faulty valve? Injector / fuel rail o-ring leak? Faulty fuel pump?

Running manifold pressure- 35 psi @ 1000 rpm, 35 psi @ 2000 rpm, 34 psi @ 3000 rpm (boat planes out at 2900 rpm), 34 psi @ 3500 rpm, 30 psi @ 4000 rpm, 28 psi at WOT (and motor chugs).

Fuel pressure regulator check: At 35 psi manifold pressure, regulator flow freely. Was not able to check if regulator stopped flowing at low manifold pressure measurement (did not want to disconnect while water testing!)

Pumping the fuel inlet ball does not eliminate chugging or increase manifold pressure.

Ignition system DVA tests:

Coil primary voltage (all cylinders were equal): 140 volts @ 1000 rpm, 180 volts @ 3000 rpm.

Spark check: Spark looked good on gap tester

Timing check: 2-degrees ATDC @ idle, 18-degrees BTDC @ 3000 rpm, ~22-degrees BTDC @ 4000 rpm. Gets eratic when engine is chugging.

Stop circuit (tested outer switch box only due to access): 225 volts @ 1000 rpm, 300 volts @ 3000 rpm.

Low speed Stator input to outer switch box: 200volts @ 1000 rpm, 260 volts @ 3000 rpm. With ignition stabilizer disabled (disconnected wht/blk bullet connector), 100 volts @ 1000 rpm, 310 volts @ 3000 rpm.

High speed Stator input to outer switch box: 140volts @ 1000 rpm, 270volts @ 3000 rpm. With ignition stabilizer disabled (disconnected wht/blk bullet connector), 100 volts @ 1000 rpm, 310 volts @ 3000 rpm.

Switch box bias test: 6 volts @ 1000 rpm, 20 volts @ 3000 rpm. Same results with ignition stabilizer disabled.

Detonation sensor check (tester set at 200 MV): Idle (on muffs)- 1.4-1.0 volts @ 1000 rpm, .1-.2 volts @ 2000 rpm, .1-.2 volts @ 3000 rpm, 1.6 - 2.0 volts @ 3500 rpm, 2.0-2.6 volts @ WOT (engine chugging)

Detonation module check (tester set at 20VDC): 2.2-3.0 volts @ 1000 rpm, 2.4-3.1 volts @ 2000 rpm, 1.7-2.5 volts @ 3000 rpm, 1.0-1.5 volts @ 3500 rpm, .2-.5 volts @ 4000 rpm, 2.0 volts @ WOT (engine chugging)

 

[bill200xri]

Re: 200xri limited to 3500 rpm

Just wanted to end this post by stating that the problem is solved. It was a clogged inal fuel filer, just downstream from the high pressure pump. I replaced it and the motor tops out at 5400 rpm.

Thanks for all the help.

Bill

 

[madgadget]

Re: 200xri limited to 3500 rpm

Bill sounds exactly like how mine behaved. I am going to check the same parts tomorrow. Your tests are interesting too I shall compare with mine!

 

[madgadget]

Re: 200xri limited to 3500 rpm

Checked my fuel filter today, and it seemed fine. A little dirty but not enough to cause a problem. I'm fairly sure my problem is with the fuel pump. I just need to get a pressure gauge now to test it for sure, everything before it including the vapour separator tank fills and is fine.

 

[madgadget]

Re: 200xri limited to 3500 rpm

Found out that the fuel pump is a very common Bosch automotive type '070' That should mean I can get it at a sensible price I hope