Runaway acceleration in '94 200 Xri

[bill200xri]

I have a '94 200 Xri that has a top end issue- cannot accelerate over 3200 rpm. I went thru the Merc manual steps to check fuel system, all OK. Electrical system checks showed all is well, except I had one shorted injector. I did not do DVA tests, though. I bought an injector (ouch!), removed the induction manifold and fuel rail, blew out the rail to clean and dry, and when cheking the injector circuits prior to replacing an injector, all three circuits checked good! I put the intake system back on as is (did not replace any injectors), and verified that injectors were all spraying prior to installing the manifold cover. The motor fired up perfectly on the earmuffs in my back yard, several times over the next week. I did not get to load check on the water. It sat for two weeks (out of town). The next chance I had to play with it, it was hard to start, and started with a huge cloud of oil smoke. Then, without any throttle movement, the motor began to accelerate in a runaway fashion, and I had to kill by turning off the key switch. I repeated this a dozen times, each time with the same runaway acceleration. Any clues on what to do here?

Bill

 

[bill200xri]

Re: Runaway acceleration in '94 200 Xri

I have solved my own mystery, and posted to inform others who may have a similar issue.

When I installed the oil pump linkage (it is linked on one end to the throttle linkage that controls the air intake butterlies), I installed it to the oil pump arm 180-degrees from where it should be. The linkage was hanging up on the vapor separator, sticking the linkage (and intake throttle) open. this occurred because I would engage the throttle a little due to a hard start issue. Once it started, the engine would naturally accellerate.

I installed the oil pump linkage where it should be, and the problem is solved.

Now on to why I started messing with it inthe first place....boggin down at above 3200 rpm.