2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

[ermess]

2001 90 hp Johnson runs great for 5/10 minutes then only wants to run 2800 rpm. Owner had me install a water seperator filter. I installed seperator 6" above external fuel tank under center console. He ran boat off and on for 3to4 hours. On the way back to dock boat started acting up and would not run over 2800rpm. Let it set awhile and boat would get up and run for about 5 minutes than shut down to 2800 rpm. When I got to boat - I bypassed fuel seperator and bulb - hooked fuel line straight to tank. Boat would get up and run for 5 minutes and fall back to 2800rpm. Changed plugs - same thing.<br />Checked compression 120 on all 4 cylinders.<br />Spark checked- good clean spark.<br />Duplicated running condition put tack on each ign wire - they all read the same - engine would build speed to 2800 rpm but would go no further.<br />thanks for any help <br />Ed

 

[icancu2]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

I had the same things happen with a 2001 150 oceanpro. I had timing checked, sync checked ect ect ect...turns out I had a bad power pack. seems to be an problem from what I have been told. CDI makes a good one, maybe Seasport will jump in here and give you a hand he's been quite a bit of help for me. Good luck

 

[Seasport]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

Sounds like the motor is going into SLOW mode? It does this if it overheats. Revs are limited to 2500rpm when this happens and the motor shakes. It can only be reset by letting the motor cool down and then restarting.<br /><br />If it is going into SLOW mode, it could actually be overheating (have you got a good flow of cooling water) or possibly caused by a faulty temperature sensor switch, faulty powerpack or blocking diode.<br /><br />Do you have a service manual? Good place to start.

 

[ermess]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

No I do not have a service manual for this particular engine. At what temp is SLOW activated normally? Can I check temp sensor by unplugging tan wire at temp sensor harness or is their a disconnect on the power pack?<br />And last, but not least where and what color wire can I find the Blocking Diode?<br />Thanks<br />Ed

 

[ermess]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

Guys,<br />Just got off boat. Unplugged temp sensors boat ran great. Starboard temp WOT climbed to 186<br />Port temp WOT climbed 134-145<br />Idle temp Starboard 145-160<br />Idle temp Port 140-147<br /><br />Plugged sensors back in - could not duplicate SLOW (2600rpm) running condition. Boat ran great. <br />Are Starboard side known to run hotter or should there be a concern- I replaced tstats about 2 weeks ago that seemed to bring starboard side down in temp, but there is still a difference.<br />Not sure whats going on.

 

[ermess]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

Another possible issue - While I was sitting on the back of the boat shooting WOT temp, I noticed water coming from top midsection cut out area next to transom (little square like cut out area facing transom on midsection -shift rod visible) Water was cold and only showed up at WOT?

 

[Seasport]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

I'd say you're running too hot on the starboard side. Haven't got the manual here and can't remember at what temp SLOW kicks in, but you should be running no more than about 160-165 degrees at WOT. You should be able to hold your hand on the heads for a couple of seconds.<br /><br />I'd check out that water. Sounds like you have a leak around the powerhead base.<br /><br />Doesn't really explain why your problem has now gone away. SLOW can activate if the tan wires are run too close to the spark plug leads. Maybe this could have been a problem??

 

[Seasport]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

I checked the manual. The temp switch which activates SLOW closes at 240 degrees and opens again at 207 degrees. So you're well within that (although your starboard bank is still running too warm).<br /><br />Bit of a mystery why your SLOW was activating and not now. Faulty switch maybe?

 

[ermess]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

As for water pouring out of top of midsection facing transom - pulled plastic midsection covers removed lower unit and attached hose to water tube - pressurized system no water leaking out of top midsection - inspected water pump gasket and grommets around water tube, drive shaft, and shift shaft - all intact and in good shape. reinstalled gearcase - ran with flush attached - revved engine to 3000rpm - water shows back up at top of midsection - since I have plastic off, I can see that it is coming from the drive shaft area (if you are looking at it from transom facing steering arm- the water is coming from below the steering arm assy, at the mating surfaces of the two horizntal rubber motor mount boots) and the water is warm.

 

[Cricket Too]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

Are you running this thing on earmuffs or just with the hose connected to the backflusher, you say you ran it with the flush attatched, if that means the backflusher, your gonna smoke that waterpump pretty quick, especially if you rev to 3000 rpm. Definitiley run it on earmuffs.

 

[ermess]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

With the gearcase attached I run it with the earmuffs attached - when I removed the gearcase I ran a hose attachment to the tube.

 

[ermess]

Re: 2001 90 hp Johnson runs great for 5/10 min. then only runs 2800 rpm

Removed Tstats - head temp 105 +/- 5, water quit pouring out of top of midsection. Will keep you posted. Water Temp in Lower Laguna Madre 88 degrees. Keep ya posted.