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Johnson Fast Strike 150 stalling under load

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Baxter83

Member
I have a 1994 Johnson Fast Strike 150 that I just had the powerhead rebuilt in the fall. It starts right up, idles great, has good compression across the board, will rev up in and out of gear, and runs perfectly in the driveway with muffs on, but when I put it on the water to try it out for the first time yesterday it will not plane out and will stall if I try to throttle it past 1500 or so RPM's. I'm at my wits end. I'm sure that I left out information, but if anyone has had this happen or has seen it before feel free to chime in.

BTW, I'm new to this forum. I'm from Tennessee.
 
My 1988 150 did that and it turned out to be carbs needed to be cleaned out and rebuilt. Everything else tested ok. Hope you can get it fixed. Good luck.
 
Will Bark said:
My 1988 150 did that and it turned out to be carbs needed to be cleaned out and rebuilt. Everything else tested ok. Hope you can get it fixed. Good luck.
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Thanks for the reply. They rebuilt the carbs at the shop when they did the power head. It's the same symptom, but I think that issue can be eliminated.
 
It runs " great " on the trailer because there is no work to do.----Even in gear it is still in neutral as the prop only moves air !------So check to make sure you have spark on all 6 leads.---
 
racerone said:
It runs " great " on the trailer because there is no work to do.----Even in gear it is still in neutral as the prop only moves air !------So check to make sure you have spark on all 6 leads.---
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Yes, I understand it's unloaded out of the water. That detail was just thrown out there.

What's the best way to check for spark at each cylinder? I've never checked an outboard, just lawnmowers.
 
You can get a spark checker at any auto supply store and check that spark jumps at least 3/16 in. If you have spark on all cylinders Racerone can give you other aeas to check. Good luck.
 
Use an air gap spark tester. You can put the tester on one cylinder then ground the other 5 and test while cranking. Or, you can run the engine with the tester on each cylinder.

The gap should be 7/16".

I would also suggest doing this with the LU submerged. So, either perform the test at the boat ramp, or have the LU in a tub of water. Either way, the back pressure from the water gives you a better indication of how it's working.

KJ
 
Thanks for all the feedback! I contacted the shop that rebuilt it and they said all 6 we're firing. I think it'd be pretty cheap and easy to check for myself for verification though. The shop is 1-1/2 hours out.

What is the sync or link? Is one the sensor on the lower part of the throttle linkage on the starboard side?
 
racer or fastbullet can explain link and sync much better than I hope they will chime in and explain how to do it. Good luck.
 
Is the timer base rotating , yes or no ?----Is oil injection in service , yes or no.-----Have you checked for spark on all 6 leads , yes or no ?
 
Specifically, how do I check the timer base rotation?

The oil injection is electrically disconnected and lines plugged

I haven't checked for myself, but the shop that did the rebuild said yes, there was fire on all 6.

I apologise for my ignorance btw...lol
 
One more thing... When I brought it out I noticed that the alarm would go off every minute or so while the engine was running. After getting it back home I researched to find if something from the VRO still needed to be disconnected and found that they left one of the harnesses plugged in (located just behind the trim switch on the engine cowling). I disconnected it and the alarm stopped (this is while running/amateur troubleshooting in the driveway later that day). Would this alarm keep the engine from turning more than 1500 RPM's? I mean, it would hit 1500 RPMs and die while on the water unless I backed off the throttle.
 
They said they did, but I'm skeptical. I'd rather not mention who until I can verify any kind of negligence on their part. It was a licensed marine shop though...
 
I put it back in the water today. Basically the same problem, but unplugging the harness I mentioned above eliminated the low oil alarm every 40 seconds, but holding the choke when trying to throttle down on it in gear didn't help. Oh, and I checked for spark and all 6 are firing.
 
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Baxter83 said:
I put it back in the water today. Basically the same problem, but unplugging the harness I mentioned above eliminated the low oil alarm every 40 seconds, but holding the choke when trying to throttle down on it in gear didn't help. Oh, and I checked for spark and all 6 are firing.
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I am very much a novice, and everything I know was learned on these forums since last autumn, so my input needs to be checked with the experts. I have an engine similar to yours, and I had similar issues, but they happened way before 1500 rpms. My engine would stall when I put it in gear, on the water. But it of course seemed healthy on the earmuffs because I wasn't asking it to do much of anything, and certainly not asking it to do what it is designed to do - operate in water with back pressure and a load.

Racerone and others should check my response, but maybe the tach is wrong, and the engine is in SLOW mode? I don't trust my tach much anymore.
 
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Problem solved!

There was water intrusion in the 1, 3, & 5 cylinders. Apparently the O-rings installed during the rebuild on that side were the wrong size. She runs like a top now. Thanks for all of your input everybody!!
 
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