low RPM at WOT

[dsteers]

Howdy,<br /><br />I recently purchased a 1990 Evinrude 110 HP outboard. The unit includes the VRO oil injection system. <br /><br />We took our first shakedown cruise and found the motor would not rev over 2500 RPM, even at WOT. We piddled around for a half hour, then the boat responded to the throttle and ultimately hit 54 MPH. <br /><br />We throttled back, drove about a half mile at 2000 RPM, then the same problem recurred.RPM's Wouldn't exceed 2500 RPM.<br /><br />Changed the plugs and gas filter, found one HT lead disconnected on one of the coils and reconnected it, but when we went back to the lake the problem was about the same. <br /><br />Yesterday I found the pulse hose was very loose, so I clamped it. Haven't gone back to test it yet.<br /><br />I suspect there is a fuel starvation problem, related somehow to the VRO pump. Haven't done anything with the carbs yet, nor have I tried a portable fuel tank.<br /><br />Looking for some guidance or suggestions. I have the Service manual, but there aren't any similar troubleshooting tips.<br /><br />Sincerely,<br /><br />Doug

 

[dsteers]

Re: low RPM at WOT

Still hoping for some advice.

 

[JB]

Re: low RPM at WOT

Howdy, Dsteers.<br /><br />Sounds like you are dropping one or two cylinders intermittently.<br /><br />Try pumping your primer bulb when this happens. If it picks back up you do have a fuel starvation problem. <br /><br />I think it is more likely a carb problem or a powerpak problem.<br /><br />If you can, try to determine which cylinders are making power when it slows. If they are side by side it is a carb problem, if it is one bank, it is a powerpak problem.<br /><br />Good luck.

 

[DJ]

Re: low RPM at WOT

dsteers,<br /><br />Only a few thgings will slow it down.<br /><br />1. Losing spark on one or more cylinders. Can you run it on muffs in the driveway? If so, run it and pull high tension leads one at a time and see if there is a difference.<br /><br />2. Restricted fuel flow. Is the fuel tank properly vented? Does the primer bulb stay hard when the engine is running?<br /><br />3.. What do the spark plugs look like? Are any of clean, looking like new?<br /><br />Typically, the VRO won't have an effect on this, it will either run or not at all.

 

[dsteers]

Re: low RPM at WOT

Primer bulb seems to be hard all the time. Motor will rev to 5000 RPM when NOT in gear. When it is in gear, it won't rev. <br /><br />I'll yank the plugs to see how they look. <br /><br />Thanks,<br /><br />Doug

 

[dsteers]

Re: low RPM at WOT

Checked the plugs and all 4 are identical; a little black and oily. Thseswere recently changed an have about 1/2 hour of low RPM operation on them.

 

[dsteers]

Re: low RPM at WOT

Found the culprit. Took the boat out and disconnected one plug wire at a time. Cylinder # 4 aappears to not be firing. Engine runs the sale with or without the plug wire connected. Removing any other plug wire causes the engine to sputter or quit entirely.<br /><br />I've ohmed out the coil and it checks OK according to the manual. I am down to suspecting the carb on this cylinder. Could the float be sticking the needle valve closed?<br /><br />Can the carb be disassembled and reassembled without having to buy a kit?<br /><br />Is it possible the fuel line to this carb is clogged? <br /><br />Tomorrow I'll remove the carb.<br /><br />Thanks for everyone's suggestions.<br /><br />Doug

 

[jeemtp_99]

Re: low RPM at WOT

Hello,<br />I had a smiliar problem with my 88 Bayliner. I tried many things also but what it ended up being was 2 bad spark plug wires and corrosion on the distributor cap where the plug wires connect. I replaced all the wires and cap and it worked great. Hopefully this helps cause its a cheap fix.<br />Jason

 

[JB]

Re: low RPM at WOT

Howdy, DSteers.<br /><br />It is a fairly simple test to see if you have spark to #4. Do that first.<br /><br />If you have spark, check the compression.<br /><br />If the spark and compression are good, pull the carb that feeds #4 and inspect the reeds for #4.<br /><br />If the reeds look okay, dismantle and clean the carb. Give particular attention to the throat that feeds #4.<br /><br />Good luck.

 

[JB]

Re: low RPM at WOT

AAARRRGGGHHH!!!!<br />Why can't you keep your topic together??<br /><br />So, you have a dead cylinder. Have you checked the compression?? Have you inspected the reeds?<br /><br />A broken reed will disable the crankcase as a pump to push fuel/air mix into the cylinder. Only if fragments of the reed got into the cylinder and broke a ring or tore up the cylinder wall will it affect compression.<br /><br />If you want help, you have to supply information in a usable form. Scattering you topic among two posts only confuses us and delays getting your engine fixed.

 

[dsteers]

Re: low RPM at WOT

I do appreciate the help. However, If it makes you feel important to chastize someone, try yelling at your dog. I don't think you'd take that **** ant tone if we were face to face.

 

[JB]

Re: low RPM at WOT

Sorry about the outburst, DSteers. It was late in a long day.<br /><br />It can get frustrating when you are trying to help and your advice gets ignored in favor of starting up a new conversation somewhere else.<br /><br />Have you checked compression? Have you looked at the reeds?

 

[dsteers]

Re: low RPM at WOT

Hello JB,<br /><br />Yeah, me too. Sorry about being a grump. <br />1. Needed my morning Java, <br />2. I was screwed by "smart guy", failing to disclose a known problem.<br />3. I'm PO'd at myself for beleiving aguy with a Range Rover and a manicure.<br /><br />I yanked the head to find the piston in #4 to be completely destroyed. Never sen such damamg, even on my ond alcohol burning dragster

 

[JB]

Re: low RPM at WOT

Hmmm. I sure can see why you would be on edge.<br /><br />Just one more reason why on-the-water tests are only part of ensuring that you are getting what the seller claims you are getting.<br /><br />I hope you wont mistrust everyone who drives a Range Rover after this. Liars and cheats might drive anything.<br /><br />My sympathy.