2012 3.0L TKS runs great with muffs, but slow on lake...

[GeorgioP07]

I saw new fuel pump but was fuel pump pressure measured under load ?

my other hobby is old cars - its a chronic issue with mechanical fuel pumps these days - the pressure output is all over the place, even on what was historically considered good brands

I stated in OP that I did not test the fuel pressure.

 

[GeorgioP07]

Jumping in late on trying to noddle this issue that is perplexing and get the OP back on the water. To help with that below is a summary to date with some items that are perplexing (perhaps only to) me.

• Bought late last season all was good and ran WOT at 35+ MPH.
• Did a bunch of maintenance items last season and still ran good at 35+ MPH (this is implied but if not the case, please correct)
• Self-winterization
• This season issues with idling > needs to be at 900 (vs 750) and does the shake and will not get above 15 MPH / 2900 RPM at WOT
• Lots of items replaced / checked including
  • New fuel pump
  • Rebuilt carb
  • Timing including the advance
  • Compression was a little higher than normal. Also I do not understand “let the gauge sit for a few minutes on each cylinder test, and there was no leaking”. And OP noted one of the plugs had a loose electrode insulator.

An indication that the test of of pulling plug wires one at a time to note the RPM drop was done BUT I am usure this has been done. There was a “spark test” in post #3 but was not a pull the plug wire and note the RPM drop that I can see. OP is going to do that test again to be sure (post # 36).

Given the rough idle + needing to be higher than usual + poor performance on the water I am leaning to a cylinder not contributing.

My suggestion:

1. Pull all the plugs and disable the coil (unplug the dizzy) and while a helper is turning the motor over, look for any spray or mist that is coming out of the spark plug holes.
2. Put back together and redo the pull one spark plug wire at a time while engine is idling and note RPM drop. Note: when reinstalling the plug wires from test 1 above, put it on enough to ensure a good connection but not fully. This will make it easier to pull off the wire. When you initially start the motor if its running rougher than normal, one of those wires needs to be seated more. Wear good insulating gloves.

And post results of above two tests. Thanks.

Just to point out to all and Thanks - I am getting on the water, its just not 100% where it should be. Maybe somewhere between 75%-85% overall right now.
In NE Ohio now, we only have about 3 weeks left before most all go into storage.
Cold starts at the dock/launch are embarrassing now. It's like a dinner bell for every backyard mechanic within a mile to come over and stare at us.
Next step is to measure the spark gap, I just received the tool today. I have it set to 1/4" or 6.4mm. I expect to see a healthy blue spark per cylinder.
Then I will idle, and pull the plug wires off, one at a time with rubber gloves, and listen for consistent RPM drop per cylinder.
If the engine stalls when I remove one of the plug wires, will post that as well.
You are correct on all the above statements. I watched somebody on YouTube let his Compression gauge sit for some minutes, and it went down slowly on its own, he later said he had a leaky valve. My gauge has a tire valve (inline). I think that the gauge only records and holds the highest values, so never mind the leaking comment.
If one of the four cylinders is not contributing, would I still see combustion residue on all 4 plugs?
I have an ounce of Marvel Mystery Oil soaking in each cylinder, 24+ hours , in case that matters.
Per Racerone's comment above, If I have to remove the valve cover to look for a stuck valve at some point, I assume that gasket needs replaced? Thanks.

 

[GeorgioP07]

Just to point out to all and Thanks - I am getting on the water, its just not 100% where it should be. Maybe somewhere between 75%-85% overall right now.
In NE Ohio now, we only have about 3 weeks left before most all go into storage.
Cold starts at the dock/launch are embarrassing now. It's like a dinner bell for every backyard mechanic within a mile to come over and stare at us.
Next step is to measure the spark gap, I just received the tool today. I have it set to 1/4" or 6.4mm. I expect to see a healthy blue spark per cylinder.
Then I will idle, and pull the plug wires off, one at a time with rubber gloves, and listen for consistent RPM drop per cylinder.
If the engine stalls when I remove one of the plug wires, will post that as well.
You are correct on all the above statements. I watched somebody on YouTube let his Compression gauge sit for some minutes, and it went down slowly on its own, he later said he had a leaky valve. My gauge has a tire valve (inline). I think that the gauge only records and holds the highest values, so never mind the leaking comment.
If one of the four cylinders is not contributing, would I still see combustion residue on all 4 plugs?
I have an ounce of Marvel Mystery Oil soaking in each cylinder, 24+ hours , in case that matters.
Per Racerone's comment above, If I have to remove the valve cover to look for a stuck valve at some point, I assume that gasket needs replaced? Thanks.

Ran the tests this afternoon:
1. Garage smoked like a KISS concert in 1978 due to 1 oz of Marvel Mystery Oil per cylinder for 24 hours +.
2. Spark gap test tool showed good blue spark at 6.35mm (1/4") on all 4 cylinders,. Once in a while the spark was yellow (does that mean that the coil is on its way out?).
3. Ran at idle, and detached each plug wire one at a time, and noticed drop of 200-300 RPM per cylinder while detached, and returned to regular RPM's as soon as re-attached. The engine sounded smoother overall after the Marvel Mystery Oil soak, but l still got shocked through rubber gloves, oh well.
I suspect that my dash tachometer is reading high, because I lowered the RPM with the idle screw at the carbourator, and the dial on the gauge did not read lower as it should have, but that is more of a nuisance at this point.
Please let me know what else I can try at this point.

 

[ESGWheel]

I do not come close to the expertise of others on this forum but thru the few years I have been active I can attest those experts and myself have only one interest > to get you back on the water with a good and safe running boat. So don’t give up on us yet!

You do have a head scratcher, and I was about to post some questions when you post # 43 popped up answering some of them. But not all and added some new ones. So here goes.

Can you explain what you mean by upon start up its like ringing a dinner bell? A video if you have one would be great. Idea here is how it behaves and sounds at start up may be an indicator of the problem.

For the oil in the cylinders > did you do this today? Why? BTW, and others may know better, but seems to me that 1 oz of liquid in the cylinder is a lot and then starting the engine (even if after 24 hrs). Reason is since the oil is not compressible, could break things like piston rings.

Also did you put oil into the cylinders just prior to the compression test? This would explain the higher than usual number and eliminate the need for my test no. 1 on post 39 but does require another test (outlined below).

Combustion residue > by that I assume you mean what spark plugs normally look like, so even if you had a weak cylinder, you would get that, perhaps not the same looking but could be there.

If one of the cylinders has little impact (no drop on RPM) when pull the wire > that is the weak cylinder. Which you apparently do not have.

It’s always best to replace gaskets as it may break or otherwise not seal properly when reused.

And while the symptoms suggest a weak cylinder the data is not. And it’s really odd doing better now. Regardless here are my suggestions:

1. Redo the compression test on a warm engine. BUT do not put any oil in the cylinders. Instead disable the spark (pull plug off dizzy) and with the throttle wide open, redo the test and post results. Here is the thinking > If you put oil in the cylinders prior to the test you did before, it may have given you false reading. Post results.
2. My other thought is the carb has blockage in the high-speed circuit. Try this old school trick prior to pulling apart the carb again > disable the ign (no spark), remove the spark arrestor and with a helper to turn over the engine, place your hand over the throat of the carb to seal it off. Crank the engine for about 10 seconds. From there it should be well flooded, so best to pull the plugs, crank it over for 30 sec and put all back together. Idea here is to ‘suck out’ any blockage. Not a guarantee but hey, worth a try.
3. Also, need to pursue Scott06’s idea about fuel delivery. Given its behaving better now, I also think this could be an issue (does not explain the rough idle). Install a fuel pressure gauge in line with the carb. I assume you have rubber hose to the carb which will make it easier > need to get a T fitting, fuel line and clamps to install. Caution: secure the gauge (zip ties) so that it can be read underway and that all the lines / gauge are not interfering with anything rotating. Also need 2 people to do this, one to drive and one to read the gauge. Idea here is to record the pressure at idle and all the way up to WOT when it starts to bog down. If any questions or help needed with this just ask.

Oh, just occurred to me to ask: when it does not get to proper speed, does the motor temporarily ramp up to 4500+ RPM and then come back down to 2500 or so?
Thanks.

 

[GeorgioP07]

I do not come close to the expertise of others on this forum but thru the few years I have been active I can attest those experts and myself have only one interest > to get you back on the water with a good and safe running boat. So don’t give up on us yet!

You do have a head scratcher, and I was about to post some questions when you post # 43 popped up answering some of them. But not all and added some new ones. So here goes.

Can you explain what you mean by upon start up its like ringing a dinner bell? A video if you have one would be great. Idea here is how it behaves and sounds at start up may be an indicator of the problem.

For the oil in the cylinders > did you do this today? Why? BTW, and others may know better, but seems to me that 1 oz of liquid in the cylinder is a lot and then starting the engine (even if after 24 hrs). Reason is since the oil is not compressible, could break things like piston rings.

Also did you put oil into the cylinders just prior to the compression test? This would explain the higher than usual number and eliminate the need for my test no. 1 on post 39 but does require another test (outlined below).

Combustion residue > by that I assume you mean what spark plugs normally look like, so even if you had a weak cylinder, you would get that, perhaps not the same looking but could be there.

If one of the cylinders has little impact (no drop on RPM) when pull the wire > that is the weak cylinder. Which you apparently do not have.

It’s always best to replace gaskets as it may break or otherwise not seal properly when reused.

And while the symptoms suggest a weak cylinder the data is not. And it’s really odd doing better now. Regardless here are my suggestions:

1. Redo the compression test on a warm engine. BUT do not put any oil in the cylinders. Instead disable the spark (pull plug off dizzy) and with the throttle wide open, redo the test and post results. Here is the thinking > If you put oil in the cylinders prior to the test you did before, it may have given you false reading. Post results.
2. My other thought is the carb has blockage in the high-speed circuit. Try this old school trick prior to pulling apart the carb again > disable the ign (no spark), remove the spark arrestor and with a helper to turn over the engine, place your hand over the throat of the carb to seal it off. Crank the engine for about 10 seconds. From there it should be well flooded, so best to pull the plugs, crank it over for 30 sec and put all back together. Idea here is to ‘suck out’ any blockage. Not a guarantee but hey, worth a try.
3. Also, need to pursue Scott06’s idea about fuel delivery. Given its behaving better now, I also think this could be an issue (does not explain the rough idle). Install a fuel pressure gauge in line with the carb. I assume you have rubber hose to the carb which will make it easier > need to get a T fitting, fuel line and clamps to install. Caution: secure the gauge (zip ties) so that it can be read underway and that all the lines / gauge are not interfering with anything rotating. Also need 2 people to do this, one to drive and one to read the gauge. Idea here is to record the pressure at idle and all the way up to WOT when it starts to bog down. If any questions or help needed with this just ask.

Oh, just occurred to me to ask: when it does not get to proper speed, does the motor temporarily ramp up to 4500+ RPM and then come back down to 2500 or so?
Thanks.

Hello ESGWheel,
I appreciate you and others hanging in there while I try to sort this out.
1. "Like Ringing a Dinner Bell" Sorry, its a slang term for when a crowd gathers. Seems like anytime I have trouble at the dock, I get a lot of unwanted attention, and irrelevant advice.
2. Adding Marvel Mystery Oil to each cylinder. I was worried about Racerone's post about having a stuck valve, that was just yesterday. I never did that before. It seemed to burn off pretty quick and quiet things down. Compression test was done 3 days ago with no oil in the cylinders.
3. Yes Combustion Residue: All 4 plugs look very good, If you were to look up one of those spark plug wear indexes, these would fall under the condition of normal wear.
4. When I rebuilt the carburetor last month, I did reuse the OEM float, because it was still good, I read reviews about those that are electronically welded plastic floats that come with these kits failing in the middle of the lake as that weld cracks, gas seeps in and they no longer float and the motor won't start no matter what. Also the kit did not come with the "Power Valve Assembly", so I cleaned and re-used the existing one after it came out of the ultrasonic cleaner.
5. The throttle lever has three positions, A, B, and C. Mine was on B. The manual says "to Move it to position A if you want to get more fuel to the carburetor" or similar, but I left it where it was on position B. I had rebuilt quite a few carburetors before, and nothing stood out in particular as difficult or weird this time.
6. I can go to buy a fuel pressure testing kit, but I read that the expected pressure for this fuel pump is only 4-7psi, and most kits that I am seeing for sale go to 140psi , so the scale is pretty far off. I read that some special GM attachment is needed but not included. That's probably why I waited this long, but if you think its time, then its time and I will order one tomorrow. If you have a model that you recommend, that would be great. The fuel pump on this motor is the one that has the intake and outlet on the same side, cause the motor mount takes up the front half, they are harder to find and more expensive. Note: I was having this problem with the low RPM's in June before I replaced the fuel pump in July (and the filter element is in the bottom).
7. With the wide-open throttle and return. On the muffs, if I rev to 4000 RPM, and then throttle back to neutral , then the RPM's come back down to idle. On the lake, the most I can rev to is maxed out at 2900 RPM's, and when I throttle back down from there, it also returns down to the previous idle.
Thanks, and I will probably have a few questions when the fuel pressure test kit gets here.

 

[ESGWheel]

A lot to take in but wanted to reply quickly before my bedtime limit on posting.

Regarding the slang about the dinner bell > I get it was slang. What I was interested in knowing is the “why” folks were gathering. Made up example: Every time I start my boat it makes a large cloud of smoke and backfires like heck which folks then come ask if I need help. So, looking for the reason folks are coming around > is it due to unusual sounds or smoke or just what?

You do not want a 140 PSI gauge. You are correct your fuel pump is low pressure as you indicated, so you need a pressure gauge like this: link If your fuel lines are metal and not rubber then need still use a gauge like indicated but cobble together the needed fittings. Post a pic of your pump / carb if need help for this.