1994, 90HP Evinrude Jet boat powerhead

[Captain Ed in LJ]

I purchased a used powerhead that came from a jet boat and put it on my outboard. The guy I bought from said the idle was set (at least 1500rpm) high for the propulsion system.

I've got the powerhead running, the thottle cable is not connected, the butterflies are closed, the cam is not touching the cam follower yet the idle is very high. The idle screw has no effect on the idle. Is it possible the timing has been adjusted (for the jet boat) to create such a high idle? I don't know of anything else that would effect the idle speed.

 

[clanton]

Re: 1994, 90HP Evinrude Jet boat powerhead

The throttle pickup timing for an outboard setup is 4+- 1 degree BTDC. Check it. Check the plastic roller in the slotted linkage, clear plastic sleeve may be missing. I will check the jetboat manual tomorrow see if linkage is the same.

 

[Captain Ed in LJ]

Re: 1994, 90HP Evinrude Jet boat powerhead

That would be great if you could check the manual, Thanks!

 

[tashasdaddy]

Re: 1994, 90HP Evinrude Jet boat powerhead

it would be best if you bought the OEM Evinrude manual. if not do not screw with your engine.

 

[ezeke]

Re: 1994, 90HP Evinrude Jet boat powerhead

Get the TurboJet manual, part #502138. http://www.outboardbooks.com/index.cfm?fuseaction=search.main

 

[Captain Ed in LJ]

Re: 1994, 90HP Evinrude Jet boat powerhead

I've got the Big John manual on CD. The basic question here is, could the timing be so far advanced to create such a high idle? Or perhaps the carbs were rejetted to create this high idle, is that possible?

If the butterflies are closed it could only be one of those possibilities? I really appreciate the help! Thanks!

 

[ezeke]

Re: 1994, 90HP Evinrude Jet boat powerhead

Idle is adjusted with the boat in the water unrestrained and warmed up so that there is a load on the engine; do not attempt to adjust on a flushing device.

Synchronization and linkage adjustment is a step-by-step procedure that must be done in the order specified in the service manual for your specific motor.

The CD manual that you have is a very general aftermarket product that while useful, is not designed for servicing the TurboJet.

You can check the base timing statically following the procedure by Joe Reeves in the Engine FAQ Forum, here at iboats.

The maximum spark advance is 28? +/- 1? BTDC.

 

[Captain Ed in LJ]

Re: 1994, 90HP Evinrude Jet boat powerhead

Yes, I was just useing the Reeves method with mixed results. I'm going to put it in the water and try again. Thanks!

 

[clanton]

Re: 1994, 90HP Evinrude Jet boat powerhead

The link and sync same as outboard except for the pickup timing.Pickup timing for 115 turbojet is 5 degrees BTDC. When you change the idle screw, you are changing the timing.
What is the timing at idle now?

 

[ezeke]

Re: 1994, 90HP Evinrude Jet boat powerhead

Pickup timing for the 90 and 115 in the factory manual for this specific engine is 4? +/- 1? BTDC.

 

[Captain Ed in LJ]

Re: 1994, 90HP Evinrude Jet boat powerhead

Well thanks for all the replys. I used the Reeves method, went so far as to take the timing arm off the throttle linkage but could not get the timing close enough to the pointer. The mark was at 12 O'clock the pointer at 1, O'clock. Thought maybe the flywheel shifter so check TDC, was ok.

I caved, didn't want to burn anything up so I took it to my local shop : ( Who, doesn't like to return phone calls! Thanks anyway!!!

 

[Captain Ed in LJ]

Re: 1994, 90HP Evinrude Jet boat powerhead

I took my boat out of the shop due to the lack of progress! After changing the Timer Base and Ignition unit I pin pointed the no start problem to the stator. So all three pieces are new.

I?ve timed the engine and it now runs smoothly except it jerks every 20 seconds or so at idle. In the driveway on the muffs it?s not that noticeable but when I put it in the water the jerk becomes amplified, so much the engine dies after it jerks. Could this be a reed problem?

Also while in the shop they said they changed a bearing on the propeller shaft, now it doesn?t go into reverse, even with the cable adjustment at it?s longest point. If I disconnect the shift cable I can get in into reverse by moving the lever by hand. What would cause reverse to require this extended movement? A missing thrust washer. Thanks for all your help in advance!

 

[ezeke]

Re: 1994, 90HP Evinrude Jet boat powerhead

Edit

 

[boobie]

Re: 1994, 90HP Evinrude Jet boat powerhead

I thought he said he had a jet drive power head on an outboard.?

 

[ezeke]

Re: 1994, 90HP Evinrude Jet boat powerhead

I thought he said he had a jet drive power head on an outboard.?

My mistake, I'll edit the comment.