60 HP bigfoot won't run over 3k rpm?

[pataterchip]

I have a 2001 60 HP 4 stroke 4 cylinder that is carbureted. On the water hose it runs fine idle on through close to 6K rpm, put it gear on the hose runs fine idle to almost 6K. At the lake idles fine, in 5mph zone its fine, after 3K rpm it bogs and wants to stall. If I take it out of gear and use the high idle lever it will rev and idle just fine. If I try to rev it quickly it really wants to run but then stalls or bogs after just a quick second. Please anyone have any suggestions or at least a place to start I just bought the boat and really want to get her running good?
Thanks in advance for any advise you can lend i would sure appreciate it.

 

[HORACIO]

Re: 60 HP bigfoot won't run over 3k rpm?

I should start searching out of the engine, gas line for example. Looking for air intakes or any restriction in the gas flow. The fault seems like gas shortage to me, but I`m not and specialist, sure same expert will give further better advises. Good luck.

 

[greasemonkeyjmj]

Re: 60 HP bigfoot won't run over 3k rpm?

I have a 2001 60 HP 4 stroke 4 cylinder that is carbureted. On the water hose it runs fine idle on through close to 6K rpm, put it gear on the hose runs fine idle to almost 6K. At the lake idles fine, in 5mph zone its fine, after 3K rpm it bogs and wants to stall. If I take it out of gear and use the high idle lever it will rev and idle just fine. If I try to rev it quickly it really wants to run but then stalls or bogs after just a quick second. Please anyone have any suggestions or at least a place to start I just bought the boat and really want to get her running good?
Thanks in advance for any advise you can lend i would sure appreciate it.

I am sure some folks will agree with me, but my first suggestion would be to never run a engine at a high RPM without a load on it.it doesnt take much revving before you have to start dodging flying rods.

 

[mthieme]

Re: 60 HP bigfoot won't run over 3k rpm?

FWIW...
I had a 25 Mariner once that did the same thing.
I wound up being the stator.

 

[rtpassini]

Re: 60 HP bigfoot won't run over 3k rpm?

thats strange...a stator should never effect performance...

 

[pataterchip]

Re: 60 HP bigfoot won't run over 3k rpm?

I went though and replaced all the fuel lines and new primer bulb as well as new in line filter all just to make sure there were no leaks. No change. How can I make sure that I have good spark? Also I had it hooked up to the hose tonight and the water shooting out is very strong (I also replaced the impeller last week end) but was not very warm shouldn't the water be at least warm if not hot?

 

[pataterchip]

Re: 60 HP bigfoot won't run over 3k rpm?

Ok... compression test was good i think? It was right @ 155-160 psi on all 4, spec says cold motor should be between 180-210 when I tested i warmed the motor firt and tested @ WOT. I pulled the plugs and grounded them with aligator clips and I have spark on all 4. I replaced the spark plugs.
Quistions,
1. Is the compression test good?
2. If I pull the carbs off and clean them mainly the two jets will I have to re-sync them?
3. Can I take them apart and clean them without installing the $50 each, carb kits?

 

[MadProps]

Re: 60 HP bigfoot won't run over 3k rpm?

thats strange...a stator should never effect performance...

Bad stators can definitely affect performance on some models

402 models are notorious for having performance issues due to stators going bad
I just had a 402 with a bad stator come in....very very slight miss at idle, almost undetectable, but @ WOT the rpms drift around.
I would look into cleaning the carbs , sounds like the high speeds jets are dirty, if the carb comes apart without tearing any gaskets, reuse what you have

if this is the case also check the fuel tank & filters for debris

 

[rtpassini]

Re: 60 HP bigfoot won't run over 3k rpm?

yeah i should have known it would be different with boats, i just know with motorcycles it doesnt change performance.

 

[sschefer]

Re: 60 HP bigfoot won't run over 3k rpm?

Ok... compression test was good i think? It was right @ 155-160 psi on all 4, spec says cold motor should be between 180-210 when I tested i warmed the motor firt and tested @ WOT. I pulled the plugs and grounded them with aligator clips and I have spark on all 4. I replaced the spark plugs.
Quistions,
1. Is the compression test good?
2. If I pull the carbs off and clean them mainly the two jets will I have to re-sync them?
3. Can I take them apart and clean them without installing the $50 each, carb kits?

Answers:
1. No, you are way below factory minimum. However, if it is consitenly the same accross all cylinders then you should be able to isolate it to a single cause. Does it smoke at all on startup or when under load (it shouldn't normally).
2. You should at least check it.
3. No, you're just begging for additional problems.

My guess is that normal wear and tear is causing a loss of oil pressure under load and the rev limiter is kicking in.

On the outside chance, make sure the oil filter is new and that you fill the crankcase then run the engine briefly and then add the additional oil needed to bring it up to full. Check your spark plug gap also. If the engine is worn, you can sometimes add a .001 or .002 to the gap and it will help a little.

 

[Silvertip]

Re: 60 HP bigfoot won't run over 3k rpm?

An engine under load requires that everything from the fuel system to the ignition system be in good condition. With no load on the engine, it would rev easily even if it was running on only two cylinders. That said, get the boat back out on the water and have a passenger squeeze the primer bulb a few times and then see if it seems to come to life. If it does, you very likely have a weak fuel pump. If that doesn't help, then I'd look at the carbs. While compression is not up to spec it should still run well with those readings.

 

[pataterchip]

Re: 60 HP bigfoot won't run over 3k rpm?

Thank you very much for your help and clear answers.
I ordered the carb kits today and I will rebuild and re-sync them.
I am really hoping that this will solve my no top end problem.
The oil filter is new and is quicksilver brand.
I do not see any smoke when it starts or while reving when hooked to the hose.
What are my options if like you say, normal where and tear has made the compression low?
Will low compresion (150-160) severly effect performance?

 

[HORACIO]

Re: 60 HP bigfoot won't run over 3k rpm?

I should pay atention to Silvertip advise, It`s very easy to check the wear of the pump using the primer bulb, and perhaps you avoid to work on carbs and save further problems.

 

[sschefer]

Re: 60 HP bigfoot won't run over 3k rpm?

Low compression will affect performance in general but it should not be as drastic as you have implied. What we all have to remember is that this is a 4 stroke and not a 2 stroke so you can trouble shoot it just as if it were an automobile engine for the most part. Before you go too far, invest in a Seloc manual (40.00) and run through the trouble shooting guide for your engine. These manuals are a little confusing since they cover many engines by year and hp rather than specifically targeting one engine but they will give you the info you need to test all of the items that have been mentioned above.

The idea of a stator, coil or a power pack being bad are not far fetched. In fact those are two very common problem areas as well as fuel. The stator directly effects timing and although your engine may appear to be timed correctly, a bad stator, trigger or charge coil could be throwing it way off.
Get the book, use the test procedures to check the spec's and then go out and get the parts you need to fix your engine. This is what a mechanic would do because they know that chasing golden eggs is a waste of time and money.

 

[pataterchip]

Re: 60 HP bigfoot won't run over 3k rpm?

Thank you all for the help, My carb kits should be in today as well as the fuel pump diaphragms that I ordered. I had a couple of related questions I thought I would ask now if what I am doing in the fuel system doesn't fix the problem.

1. The timing belt seems really loose so loose I thought it might have slipped a tooth, I pulled the flywheel and the two gears align as they should but with 2 fingers I can twist the belt a full 180 degrees with little effort. I double checked the P/N and it is the correct belt. Should it be so loose?
2. In my book it tells me to test the ignition coils at RX1 ohms (please forgive my ignorance) but I do not know what RX means? My multi-meter has 1K but no RX1. Can anyone explain what this test means and how to perform it properly?

 

[sschefer]

Re: 60 HP bigfoot won't run over 3k rpm?

Use the 1k ohms setting.

 

[marlinpruett]

Re: 60 HP bigfoot won't run over 3k rpm?

What prop are you running? Too large a pitch will cause this too. I have a Mercury 30 hp 4stroke and my dealer delivered it with a 13p prop,I could hardly get 3000rpm. Changed to a 11 and all was well.

 

[pataterchip]

Re: 60 HP bigfoot won't run over 3k rpm?

I got the carb kits in and cleaned everything very well and reassembled the carbs as well as replaced the outer diaphram for the fuel pump as well as the timeing belt. I fired it up and it seems that i now have a significant mis fire I haven't synced the carbs yet but it will stall at idle speed and will only stay running if the bump up the idle to about 2500. And even at high idle it seems to have a miss. I pulled the plugs and check the gap (all were correct) I tested the ignition coil with an ohm's meter the way the book says to, on the primary side-wire going into coil (black and orange)they test good but I cannot get any reading at all on either coil on the secoundary-spark plug side of the coils. I pulled all the plugs and aligator clip grounded them, with them hooked up I had the wife crank the motor I can see all are sparking. Any one have any ideas?