2003 150hp johnson bad low end.

4.0l sahara · Aug 16, 2007

Well we have a 18ft fourwinns with a 2003 150hp v6 johnson. The motor this season will not run right in the low end when you give it just a little throttle it sputters and shacks. Every thing above that runs real good. We had this boat up to about 68mph with this motor. So we brought it to the dealer and they said the low end needed tuning sounded right so they did that and it better but still there. It has new spark plugs and we also switched to a stanless steel prop but it's the same pitch as stock. So what could it be?

reeldutch · Aug 16, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

what rpm range are you talking about?

700 - 1500?
1500 - 2500

there is no such thing as stock propeller.
size depends on load.
load depends on boat/weight.

4.0l sahara · Aug 16, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

700 - 1500rpm. When I say stock prop I mean the same pitch as the one that came on the boat when we bought it new.

4.0l sahara · Aug 16, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

anybody?

4.0l sahara · Aug 17, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

bump.

4.0l sahara · Aug 18, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

Help me!!

walleyehed · Aug 19, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

Sounds like (obviously) a miss...what did the shop do to "tune" it?
At the Rpm you're talking about, it isn't high enough to be a transition problem from the Idle to mid-range/high-speed circut. Your engine should have the equivalent of the OIS ignition system and it takes a tech that's fairly sharp to get it set-up right with the right equipment.
Have you changed plugs?

4.0l sahara · Aug 20, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

Ya The first thing I did was put in new plugs. They said they tuned the low speed on the carbs. We got it back and it was better but still not right.

4.0l sahara · Aug 21, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

bump.

walleyehed · Aug 21, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

The low-speed is nothing but air-bleeds (non-adjustable) only replacable on that engine.
The only thing they could have changed was Idle timing.
Unless someone like Dhadley steps in and says other-wise, I'd call your shop and ask them exactly what they "changed" on the carbs..

modsrx · Aug 21, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

i guess they change the little number of the bills for big one lollllll.... i hate dealerrrrrrrrrrrrrrrrr they are a bunch of .......some are good but some try everything but can fix the problem .......

modsrx · Aug 21, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

take out those main jet out and take a good look at them ..... some run regular gaz and that gaz is really messsy if u let the engine stop for a long period....

4.0l sahara · Aug 28, 2007

Re: 150hp jhonson bad low end.

Re: 150hp jhonson bad low end.

Do you guys think my new stainless prop could cause this because of the added weight. Because last year it ran alot better but not perfect. This year I put on the new prop and it doesn't run well this year. Could the prop cause this? The prop that was on there was a aluminum prop with a 19 pitch. The new prop is a Stiletto stainless prop with the same pitch of 19. Should I've whent to a 18p prop? After the motor winds up all the way it still is at 5,000+rpm.

4.0l sahara · Aug 29, 2007

Re: 2003 150hp johnson bad low end.

bump

4.0l sahara · Aug 8, 2010

Re: 2003 150hp johnson bad low end.

Okay this is old but i still need help. It's a 2002 not 2003. It still has this problem. It idles poorly and backfires sometimes and sputters. It will also stall sometimes. Anything over 1100rpm it runs like a dream and pulls 5100rpm with a decent load in the boat. I recently just rebuilt the carbs and tb's. Set float height and all that stuff. I put the low speed needle back where they were. They were all around 7.25 turns out. To me that seems like to much. Even know a few places told us they had adjusted them they were still filled with epoxy so i was the first to touch them. Also after a hot soak like if you sit for 30 min after a hard run its a ***** to get going again. It's synced right and plugs are fresh. Good compression low hours. It's getting old it has done this for to long.

jonesg · Aug 8, 2010

Re: 2003 150hp johnson bad low end.

Model number would tell everyone exactly what you're working on.

Do you have the service book?
IS it lean sneezing?

4.0l sahara · Aug 8, 2010

Re: 2003 150hp johnson bad low end.

Yes i have the book and will get model number later. Yes in water it sneeze but out it back fires

4.0l sahara · Aug 12, 2010

Re: 2003 150hp johnson bad low end.

BUMP

Im also wondering when i rebuilt the carbs the bowls were all warped pretty good. Is there a metal bowl i can buy? They arnt leaking yet but they a warped bad and i think it will be trouble later.

2003 150hp johnson bad low end.

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