Engine runs on low RPM's only!

[sunpacman]

Well, its Sunday after a long day of boating....I'm beginning to feel like a regular here....Spent all day out yesterday will no problems....then today....problems. I have twin 200's hp(93's). While running wide open, port engine bogs down to 700rps(idle). Engine appears to be cool and oil res. on engine is full. 2 weeks ago I replaced the oil pump on the remote tank. All has been fine untill today. Engine goes in gear but will not go above 1000rpms. It starts fine and idles as it should. When out in gear, it pushes water but wont rev. Please help.

 

[rodbolt]

Re: Engine runs on low RPM's only!

check the spark and the compression first. if both are good its most likly water or trash in the carbs a bad set of fuel pumps or lack of fuel to the pumps.

 

[sunpacman]

Re: Engine runs on low RPM's only!

The carbs were rebuilt just a month ago...I will check spark and cmpression but its seems as it is running smoothly on idle. I assume all cylinders are firing and compression was just checked however I will check again. What should the cylinders comp. read? (120?)Is it a manual fuel pump and is there more than one? <br />Thanks Rob....by the way, you've been helpful to a few other problems I have had. This is a new boat to me and I'm trying to do most of the repairs myself as I dont mind getting my hands dirty.<br />Gary

 

[rodbolt]

Re: Engine runs on low RPM's only!

does not matter if the carbs were rebuilt yesterday if there is trash or water in the main jets today. same with compression. yesterday has no meaning. test it again. should have less than a 10 PSI spread from bank to bank. if you suspect a fuel tank problem try switching the fuel line connectors port to stbd and retesting. if the problem shifts its in the tank and lines if not its between the engine connector, yes they fail, and the carbs. could also be the stator is failing but its rather rare. thats why I say a systematic method of testing MUST be used. the shotgun approach does not work well with outboards. eliminate engine mechanicals, eliminate ign and all it leaves is fuel

 

[sunpacman]

Re: Engine runs on low RPM's only!

Thanks Rod, <br />Its been a few years since I've tested compression myself. And in fact, I've really only tested on an auto. Is it the same procedure...can you give me a quick <br />compress. ck 101 course. Should I switch the fuel line at the water seperators? By the way, the seperators were just put on when carbs were rebuilt. They do have a small quarter size bubble in the site glass....both do.

 

[sunpacman]

Re: Engine runs on low RPM's only!

Hey Rod...One more thing ...I was running at about 5200 RPM's when the port engine shut down...it slowed to almost an idle however it stayed running....about 700 rpm's. It was then that when put in gear it would push water but had would not rev'up as throtle was increased. No alarms went off and engine appeared to be cool. I then restarted but again, would not go over the 700-800rpm's idle speed. I motored home slowly on both engines....hope this helps.<br />Gary

 

[jim dozier]

Re: Engine runs on low RPM's only!

In addition to the good advice from Rodbolt, maybe you should check the throttle cable connection at the engine. Although I couldn't tell from your description its possible the throttle linkage came undone and the engine isn't receiving throttle commands.

 

[sunpacman]

Re: Engine runs on low RPM's only!

Let me ask you something...if I take the cover off the engine while its running and push the linkage up on the carbs, the engines should rev up. This I guest should tell me if its a throtle cable problem or not? If it goes into higher rpms' it may just be a cable? Does this sound like I'm headed in the right direction?

 

[mrn714]

Re: Engine runs on low RPM's only!

Testing throttle at the engine would be a good way to rule out the cable. Had a similar issue with a 150. It was the fuel filter. Hope all goes well.

 

[jim dozier]

Re: Engine runs on low RPM's only!

Yeah, its a long shot but easy to check. If you pull the cover off you should be able to visualize if the throttle cable is working correctly and if not and you moved it by hand the engine would rev up if nothing else was amiss. Good luck.

 

[sunpacman]

Re: Engine runs on low RPM's only!

YES!!!!!!It was the throttle linkage. Theres a small plastic ball joint that is threaded at one end. It's cracked in half at the threaded end and popped off. ANyone know where I can get another plastic ball joint. In the mean time I can put a plastic stap around and re-thread over adjustment screw.

 

[jim dozier]

Re: Engine runs on low RPM's only!

You can get them at H & H Marine Sales & Service on San Martin Blvd just over the Gandy Bridge in St. Pete. Turn off Gandy Blvd at San Martin like you are going to Weedon Island. Its just a 100 yds south of Gandy Blvd. Andy will order it for you if its not in stock but I bet he has them because they are common to several models. I used to have an extra one laying around but I cleaned up after I sold my Suzuki. See you out on the Bay/Gulf.

 

[sunpacman]

Re: Engine runs on low RPM's only!

Thank you very much. I have a Yamaha Jim, but I guess they use similar parts. Thanks again for Andy's info.<br />Gary

 

[jim dozier]

Re: Engine runs on low RPM's only!

Oh I missed the brand don't know why I assumed it was a Suzuki. I think there are several good Yamaha dealers in the Bay area. Good luck.

 

[easygo0]

Re: Engine runs on low RPM's only!

hey I've got a few if your search falls through work in south tampa everyday just post and i'll hook ya up