loss of power, increase in RPM

[Ciera2450]

Hi guys,
i ran into an issue the last weekend out. Long story short, i lost power and noticed a coupled hundred RPM increase on the tach at the same time. I recently had my prop rebuilt and rehubbed, I'm wondering if the hub can slip "partially"?
I WAS able to get the boat on plane but it struggled to get there. I was also thinking perhaps a fouled plug leading to the loss of power....
The motor sounded "normal" to me despite the loss in power.
I'm heading out shortly to pull the prop and inspect it. (it appears fine while attached to the drive)
Also plan to check the plugs

Any ideas or thoughts on what to look for?

Engine is 225D, Drive is AQ280

 

[Ciera2450]

Re: loss of power, increase in RPM

Can the prop slip on the hub causing this issue? The reason I had the prop rebuilt/rehubbed was because the hub slipped, but it slipped to the point that I couldn't give it ANY throttle, could the new hub be slipping just enough to cause issues when under high rpm load?

Again, the engine sounded normal to me aside from the increase in rpm so i doubt its an engine issue....but what do i know lol

 

[Ciera2450]

Re: loss of power, increase in RPM

its NOT a prop issue. I swapped out props and still the same issue. For some reason the boat just doesn't have the power it used to. Next step will be to check plugs,wires,distributor and then fuel supply.

 

[captmello]

Re: loss of power, increase in RPM

Sounds odd, and you say your RPM's are up from usual?

 

[Tail_Gunner]

Re: loss of power, increase in RPM

I WAS able to get the boat on plane but it struggled to get there. I was also thinking perhaps a fouled plug leading to the loss of power....

Explain this: Are you saying the engine spun up smoothly and went no place and struggled to plane. Or did the engine bog down struggling to build rpm and plane

 

[skydiveD30571]

Re: loss of power, increase in RPM

A fouled plug won't give you an increase in rpms and a loss of power. That's generally contributed to a slipping prop like you were thinking. When you switched out the prop, did you switch out the hub also? What kind of props and hubs are you trying?

 

[Ciera2450]

Re: loss of power, increase in RPM

thanks for the replies guys...

It does appear the engine is "bogging" slightly when trying to plane out at full throttle. I normally hammer the throttle and the boat pops right up and then I back off the throttle when plane is acheived. The rpms don't seem to climb up as quickly and top speed is down about 7MPH.

My earlier post about the rpms increasing was some kind of glitch in the tach. I tapped on it and the rpms came back down.

The prop I used to test my spun hub theory was a known to be good spare that I keep on board. Either way, the prop wasn't the issue. I changed to the spare with the same results. Now, i'm leaning toward a fouled plug or other problem with the ignition system. I haven't had a chance to tear into things yet. Hopefully tonight I can find a few minutes to at least pull the plugs.

Wouldn't I notice a miss if a plug were fouled? At low rpm, the engine sounds normal to me.

Thanks again for the help guys!

 

[Ciera2450]

Re: loss of power, increase in RPM

The props are the original Volvo prop that I just had freshly rehubbed and rebuilt. The spare is a cheapo solas of the same size and pitch.

 

[skydiveD30571]

Re: loss of power, increase in RPM

Pulling the plugs will help tell you a lot about what is going on in each cylinder. If it is a miss it will show up on that spark plug. When was the last full tune up? Could be time to just knock that stuff out anyway.

 

[Ciera2450]

Re: loss of power, increase in RPM

Last full tune up was 2 years ago. I will pull the plugs and inspect them. I hope its something simple like that. I just thought that I would hear a miss in the engine, however thinking back many years ago...I had a mustang with a 302 that had 1 fouled plug and the engine didn't seem to miss or do anything strange either. (other than lack of power)

I'll pull the plugs in the morning and report my findings. Thanks guys

 

[Ciera2450]

Re: loss of power, increase in RPM

Ok. I pulled and changed all the plugs and inspected the wires for any wear. The plugs were all a nice chocolate milk color and appeared normal. I went ahead and replaced all of them anyways and took the boat to the lake to test things out. I also added seafoam to the fuel and changed the fuel filters.
The same issue is there!!! Grrr!

I had the wife at the helm and apply throttle while I was in the engine bay listenening and looking for anything out of the ordinary. The engine is VERY clearly sputtering when the throttle is applied. It sounds almost like a backfire but not as loud. At idle speeds the engine sounds normal but, as throttle is applied it starts sputtering and REALLY struggles to get the boat going.
I thought a fuel blockage of some kind but I removed the spark arrestor and the fuel appears to be flowing fine....

Could my timing be out of whack?
Distributor?

 

[captmello]

Re: loss of power, increase in RPM

Could my timing be out of whack?
Distributor?

easy enough to check...are you still running points?

 

[sbarn]

Re: loss of power, increase in RPM

I have the same problem just not as bad. My tops sleep was about 43mph at 4200 rpm. Right now I can't get going over 32. Boat starts and gets to plain like always it just doesn't hit top speed any more. I have ran about 10 gallons of premium gas and deadpan threw it. Seems to be getting better but not much. I was thinking I got some of the bad gas BP put out in north west Indiana. Also was think a prop problem.

 

[Ciera2450]

Re: loss of power, increase in RPM

captmello, its been converted to electronic ignition. I am going to replace the wires and dist. cap this evening and then check the timing. I can't really test out the issue tho without putting the boat back in the water. The engine needs a load on it to test.

 

[Ciera2450]

Re: loss of power, increase in RPM

Ok.... I was out trouble shooting things in the driveway. I have tested all the plug wires and i'm getting about 26k Ohms average. So, they need replaced and i will do so.

My problem comes in when I removed the coil and dist. cap. I have never messed with this part of an engine and am feeling a bit uneasy about it. Someone has replaced the dist cap with an automotive style with a top mounted coil.
Prior to removing the cap, as I was checking each plug wire, I noticed that the cap and distrubtor rotate rather easily. It didn't take much force to rotate it by hand. Is this normal? I wouldn't think so, as it would throw off the timing if it moved. This could possibly be my problem with the sputter and backfiring under load.

My issue is that i've rotated the distributor now and I'm unsure how to properly set it back and tighten it down so it doens't move as easily. I plan to replace the cap and wires.

Here are pics of where i'm at......

What is my next step guys?
I don't want to just throw money at things hoping to fix the problem. I have NEVER messed with the distrubtor and timing....I'm somewhat lost. But i learn quickly!!!!

 

[Ciera2450]

Re: loss of power, increase in RPM

To clarify the symptoms.....
Two weekends ago after a day of tubing and cruising we anchored out with no problems. Sunday morning as I left the anchor spot, the boat didn't seem to power up normally BUT it did NOT backfire or sputter, that i noticed. The engine seemed just to struggle getting the boat going, but still got on plane and cruised back to marina. I pulled the boat home thinking a fuel issue.
This past weekend.... After replacing plugs and fuel filters, we ran the boat at idle/hull speeds over to the restaurant and back with no issues..when leaving the restuarant and trying to power up I noticed what seemed like a sputter. I backed off and went back to the marina and tied up for the night.
The next morning, I had the wife drive while I stayed the engine bay looking for issues. When she applied throttle the boat clearly sputtered BADLY...I had her try to power through it and then the backfire type noises started. She throttled down and we idled back and towed the boat home.

 

[Maclin]

Re: loss of power, increase in RPM

That is an automotive HEI distributor, no HEI's were in that model year plus it has a vacuum advance can on it proving it's lineage. I do not know if it has anything to do with your problems, but you will not be able to order parts for it as an AQ225.

As far as timing, you just set the static timing as specified in the manual. However the automotive distributor may have more mechanical advance than the AQ225 is ready for and be over-advancing getting into the detonation range.

 

[Tail_Gunner]

Re: loss of power, increase in RPM

To clarify the symptoms.....
Two weekends ago after a day of tubing and cruising we anchored out with no problems. Sunday morning as I left the anchor spot, the boat didn't seem to power up normally BUT it did NOT backfire or sputter, that i noticed. The engine seemed just to struggle getting the boat going, but still got on plane and cruised back to marina. I pulled the boat home thinking a fuel issue.
This past weekend.... After replacing plugs and fuel filters, we ran the boat at idle/hull speeds over to the restaurant and back with no issues..when leaving the restuarant and trying to power up I noticed what seemed like a sputter. I backed off and went back to the marina and tied up for the night.
The next morning, I had the wife drive while I stayed the engine bay looking for issues. When she applied throttle the boat clearly sputtered BADLY...I had her try to power through it and then the backfire type noises started. She throttled down and we idled back and towed the boat home.

Heres a start: https://www.rockauto.com/catalog/x,...Search+for+ELECTRICAL+STANDARD+MOTOR+PRODUCTS

For all your boating need's. You need to get to marine and stock that dist is junk

 

[captmello]

Re: loss of power, increase in RPM

If the distributer has been slowly rotating because of being loose, that would definitely cause running issues like you're describing.

I agree with maclin, that was not the original distibutor...

to time it, you'll have to get the engine running by getting the engine rotated so that #1 cylinder, port side, first plug, is TDC on the compression stroke. Once this is in place, you turn the Distributor until the rotor lines up with the #1 spark plug wire. This should get it close enough to start. Once its started, put the timing light on it. If you don't have a timing light, find someone who does and have them show you how to use it. Its not hard, but you could damage the engine running it out of time.

Also, as mentioned, you may want to consider a new distributor. that one appears to be automotive and isn't considered safe. And it may not be performing properly.

Get the timing set first and get the boat running, then start throwing the proper parts at it!

 

[Ciera2450]

Re: loss of power, increase in RPM

Thanks Maclin! That is exactly the issue i'm having. The manuals for my engine mean nothing with this set up. It has worked fine for the two years i've owned the boat. I'm really NOT even sure this is my issue, just trying to chase things down.

So the actual distributor is not OEM?
I know the cap and coil set up are automotive replacements for sure.