Really weird motor issue, trouble starting and motor sluggish

My motor model # and type is listed below in my signature.

I've had the motor rebuilt recently.
This issue has been on-going since the rebuild.
I've recently replaced the stator since my mechanic told me the left side of motor was weak but within tolerance (barely).
I had hoped the new stator would solve the issue but it hasn't.
I've replaced the spark plugs, I've had the fuel line and bulb replaced as part of the rebuild.
The fuel pump and carb was completely rebuilt during rebuild.

The issue. (this is where it's weird)

For the last few outings, the motor will not start or at least it takes a lot of work to get it started. It tries to run but is sluggish. Keep starting, choking, checking to see if bulb is tight, etc. and the only way you can get it started is to raise the motor up so the prop is out of the water to relieve water pressure at exhaust from prop. Once you do that, the motor slowly starts and fast idle has to be slowly engaged as the motor warms. If you push fast idle lever all the way forward, motor won't run and chokes.

The bulb is not consistent and sometimes needs pumping but if the motor is running, if you pump it or choke the motor, it dies. I've changed the plugs and checked the plugs with a spark-gap test when the motor is acting up and I get bright blue sparks on each plug.

Once the motor is started and has slowly worked out whatever is causing the problem, the motor runs fine. It's slow to get on plane but at about 3/4 of the way on plane, (once the pressure is relieved) the motor runs fine and surges forward as if a fouled plug was firing correctly. After that, the motor runs completely normal and if you stop the motor and start it, it starts fine and jumps on plane like normal.

The motor issue occurs if you let the motor idle for a long period (more than 3-5mins) and if you let the motor sit for a while (like when fishing and motor is off). The longer the motor sits while not running, the harder it is to start. Only way to start it is to raise the motor to relieve pressure or to play with the choke and primer bulb. Most of the time, the bulb is tight.

I can't seem to figure out if its a fuel issue or spark issue. Spark tests show its not spark. I'm going to check the readings with a DVA meter tomorrow to rule out ignition.

I think it's a fuel issue and could be the primer bulb itslef which is a cheap fix. The weird thing is the behavior of the motor. COld starts, doesn't like to idel for long time periods (I have a 200yrd no-wake zone at my marina) and doesn't like to sit for time periods for more than 5 mins. Once motor works out the air-bubble or bad fuel mix or whatever the issue is, it runs fine and starts fine. QUick on plane, etc. Idle it for a while or let it sit and you struggle to get it started again.

Sounds like a fuel pump diaphram or faulty primer bulb to me. Any suggestions on where to look? If I can rule out ignition, it's got to be primer bulb or fuel pump. Couldn't be carb settings because it wouldn't run normal once it's warm and running well. Which leads me to thing primer bulb.

Oh and I've changed fuel to a different tank so it's not bad fuel or bad plugs either. CHanged those too.

Re: Really weird motor issue, trouble starting and motor sluggish

if i had to guess where to start looking with the details given i would surgest a carb fuel float needle is not sealing (bulb will not get hard), plugged low rpm jet or low compression on one or more cylinders.

do a compression test to check for low compression then check carbs by removing the air inlet cover and look in the carbs to see if they are soaked with gas when you pump the bulb. by tilting the motor you are tipping the carb so if theres alot of fuel passing the needle into the carb its running out the air cover. There are 2 sections to the carb one is low rpm and the other is high rpm so the carbs may need to be rebuilt as the low jet could be blocked as well which would not affect how the motor runs at high rpm.

on a side note: its not a good idea to start a motor thats tilted and these are just a few things you will have to check

Re: Really weird motor issue, trouble starting and motor sluggish

Excellent assessment. I'm thinking you're right. I'll have to take the boat back to the mechanic to get the carbs fixed under warranty.

I'll check the compression to be sure. I'll also check the carb.

Re: Really weird motor issue, trouble starting and motor sluggish

OK after thinking about this some more, I somewhat disagree or question the carb low rpm needle even though it sounds like a good place to start looking.

Why would the motor run fine at low rpm once its running correctly? If the needle was clogged or not performing correctly, it would not run correctly at all. Its running correctly once its warmed up and on plane. I agree, it sounds logical and like a possible cause but I keep goi g back to the exhaust.

The motor would not start while the prop was just under the water and tilted up. It was in a hose and in a test tank. Once the prop was above the surface (about 6"higher) it started after I choked the motor with the manual choke lever.

It seems like a fuel management issue and some sort of exhaust flow issue. Like it had air in the system or not enough spark and not enough fuel but once its running after working out whatever the issue is......it runs great. Bad fuel, spark, or carb settings are ruled out once the motor is running correctly.

Does that make sense?

Re: Really weird motor issue, trouble starting and motor sluggish

with no back pressure on the exhaust the motor could run on 2 cylinders which is why everyone is told to test a boat in water before buying as running on muffs does not prove the motor. your sounds like when started its running rich proberly due to a carb problem so rebuilding the carbs should be on your list of things to do but the first test is always compression as thats the major test. bad compression can be the death blow as its a expensive fix if the motor passes that then the carbs rebuild is next. go to any car store and they might have a compression gauge they can lend you to do the test (im thinking yours should be ok as it will sometimes play nice and run strong but lets get that test out of the way first)

Re: Really weird motor issue, trouble starting and motor sluggish

The motor is still in the break-in period for a full rebuild. I have new Weisco pistons and rings and all new gaskets. I have about 4-5hrs on the break-in and the motor has been acting this way since the very first time I took it out for the initial break in. I'll re-check the compression today and post the results. I'm suspecting 125 on the re-sleeved cylinder and 110 on the other 3 as that was my preliminary check results. I know the results should increase after the motor is broke-in but I'm thinking it hasn't changed much in only 2-3hrs of run time.

The carbs were also rebuilt with new jets, new parts, gaskets, etc. Full rebuild of the carb. I haven't ruled it out but I'm trying to see if there are other items that could be the problem.

I found this thread where the poor fella is having a similar issue yet his issue is on the high RPM and my issues are on the low RPM.
1996-johnson-150hp-ocean-runner-almost-dies-high-throttle
His sounds like a fuel management issue as well and he has replaced about as much as I have. Either something in the rebuild wasn't quite right or functioning correctly or, the carbs need adjusting more. Either way, most of this is under a 15mo warranty but my mechanic is 4hrs away. We spoke on the phone yesterday and he doesn't have any ideas on where to start. He's looking into to it and going to let me know. After we checked for various issues over the phone, (spark test, pumping the bulb as the motor is running, trying a different fuel tank, etc) none of it makes sense. The spark is good. When you pump the bulb, it chokes the motor and it tries to die so it's getting fuel yet the bulb doesn't stay hard. It's like the bulb is not priming correctly and when you flood it with fuel it chokes it so it's too rich.

I think it's a combination of things and the carb is running too rich and the bulb or fuel pump is not priming correctly and thus flooding/choking the motor with too much fuel. That's my theory. Either way, sounds like a trip to my mechanic for warranty work.

Re: Really weird motor issue, trouble starting and motor sluggish

what about the choke solenoid? Could it be sticking until the motor has worked it back into the correct position? The motor acts as if its flooded so its running rich until it finally works out the kink. Then it runs good.

Re: Really weird motor issue, trouble starting and motor sluggish

So I have checked the ignition system, checked the compression and I have checked the bulb, the fuel pump diaphram, spark plugs, etc. All is well.

I suspect a vacuum issue and the fact that the carb is running rich. What are some of the drawbacks of running rich? Gummed up rings? The spark plugs show a lot of carbon build up in just 3/4hr of run time. I cleaned the plugs and ran the motor under load on the lake in just under an hour and the plugs are already black with carbon build up. I have also checked the fuel. Seems to be OK there as well.

Motor will start when choked but does not run smooth and only runs for 5 seconds. Then 10 seconds, 15 seconds, 20-25 seconds and finally it will run but not well. THe more it runs, the stronger it gets. It eventually will run well. Once you get on plane, the motor functions 100% correct (other than fuel mix being rich).

I suspect vacuum issue and carb adjustment or bad jet. Any other ideas?

Re: Really weird motor issue, trouble starting and motor sluggish

glenn property of pam said:

do a compression test to check for low compression then check carbs by removing the air inlet cover and look in the carbs to see if they are soaked with gas when you pump the bulb

Click to expand...

I checked compression. Good there. I also removed the cover and looked. Bulb is hard and will not dump fuel into the carb.

Re: Really weird motor issue, trouble starting and motor sluggish

check the timing lever and all the linkages are moving as they should be. im wondering if a linkage has come off after the rebuild so the timing is way off at low rpm. link and sync.

Re: Really weird motor issue, trouble starting and motor sluggish

I found some slack in the fuel line connector at the motor so I replaced it with a new one. I also replaced the connector at the fuel tank as well. Motor fires up no problem now. Bulb wasn't keeping fuel going to pump. So I replaced it as well. Now it starts fine and runs good on the hose.

While I was checking the new bulb and running the motor to see if it would die or starve from fuel as it had a few minutes before becasue of the bulb....I noticed fuel pouring from the carb.

So either the carb has issues or the "Sierra" bulb I replaced is not working correctly for this motor. I'm thinking it's the carb? Any advise on why the carb would have fuel pouring from it? I'm thinking the float?

https://www.youtube.com/watch?v=pRad7meLJXg&feature=youtube_gdata_player

Re: Really weird motor issue, trouble starting and motor sluggish

Either way, the carb is not right becasue the motor is running too rich.

Re: Really weird motor issue, trouble starting and motor sluggish

CaneCutter79 said:

Either way, the carb is not right becasue the motor is running too rich.

Click to expand...

I agree,either incorrect float level or compromised needle & seat. I would also stick a timing light on it, just because.

Re: Really weird motor issue, trouble starting and motor sluggish

Lone Duck said:

I agree,either incorrect float level or compromised needle & seat. I would also stick a timing light on it, just because.

Click to expand...

Agreed. I just watched a video on Youtube on how to rebuild a carb. Now that I understand how a carb works (which is simple) I understand the issue now. Since I paid for a rebuilt carb, I'll take it back to the mechanic and let him fix it.

So the motor has about 4-5hrs on it with the motor running really rich. The plugs are black and carbed up. Should I be worried about excessive carbon buildup on the rings with only 4-5hrs? I've been using double oil and 1.5 oil. I'm concerned about the new rings sticking or gumming up in the new pistons. Is this a concern?

Re: Really weird motor issue, trouble starting and motor sluggish

Ok so it turns out after some more testing today that the cold start issue I have had all allong from the very start has been the flooding carb and NOT the bulb or the connector. Replacing the connector was a good thing but.....the lower carb has gas pouring out like a water fountain almost.

Here is a much longer video showing the motor after I got it started without the fuel line connected. After it started running I connected the fuel line and started recording.

NOTE that when I disconnect the fuel line, the fuel stops pouring from the lower carb overflow and the motor actually increases RPM's slightly and starts to run a bit smoother because the fuel to air mix is better. It eventually runs out of fuel and I start it again and hold just enough throttle to run the fuel completely out of the motor. (it's going to sit for a couple of weeks before I can get it to the mechanic)

Just wanted to update and some pre-close out this thread. I will report the final results as to what the problem was with the carb so others may benefit from this thread if it were to be found in the future. Most folks here don't close the loop on threads and it's frustrating when searching and you find someone with a similar problem and they don't report the cause of the issue.:facepalm:

:joyous: THank you all for your help. I'm just glad I have gotten to the problem and no for certain where to start looking.

https://www.youtube.com/watch?v=YY6m7S2-BIQ&feature=youtube_gdata_player

Re: Really weird motor issue, trouble starting and motor sluggish

I will have mechanic check the new stator readings, the coils, and the timing while he has it. Just to be sure.

Re: Really weird motor issue, trouble starting and motor sluggish

you are one day going to have to learn how to pull and fix a carb and the hard work was done like cleaning the jets etc. take some pictures of the linkage then take the carb off and remove the bowl. take the pin out that holds the float then lift float (some fuel shut off needles have a spring thats attached to float so what that as you remove it). clean tip of needle gentle (wipe on shirt) then look inside where the needle came from if you see no trash just blow it out if you see trash then ear bud works. put it back together then put a piece of fuel line on carb and blow down the tube while lifting the float when float is level with bottom of carb it should stop the air. if the float goes past level gentle bend the tab that pushes the needle in to the seat.

It only takes a real small piece of rubber/trash to stop the needle from seating. saves a 4hr drive to mechanic and if it all went bad he can put it back together lol

Re: Really weird motor issue, trouble starting and motor sluggish

Well I was going to do that but since I paid for a rebuild and I was going to make a fishing trip up that way anyway.....I don't mind the drive so much. Plus I would rather know that if anything goes wrong or if my compression keeps dropping, he can't blame me and void his warranty. As much trouble as this thing has given me since I got it back, I doubt he would do that. He's a good guy and I think he'll stand by his work.

He did tell me to drain the bowl and blow some compressed air into the fuel line to blow out any trash that may be blocking the pin. If that didn't work, he'd have to take the carb off and take it apart. I can try using some carb cleaner and blow some air into and see if it helps. EIther way, the carbs are set too rich on all 4 cylinders. He needs to adjust it.

Re: Really weird motor issue, trouble starting and motor sluggish

He's a good guy. SO WHY DID HE NOT ADJUST IT THE FIRST TIME ?? There should only be very minor adjustment after break in time is up.

Re: Really weird motor issue, trouble starting and motor sluggish

Lone Duck said:

He's a good guy. SO WHY DID HE NOT ADJUST IT THE FIRST TIME ?? There should only be very minor adjustment after break in time is up.

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He did adjust it before I arrived to get it. We ran it several times on the hose before I left. We would have launched the boat but I had a bearing go bad on the way up to his place so we replaced the trailer bearings and installed a new temp gauge. Had to make several trips into town for parts and such along the way. We ran out of time to launch the boat as I had a 4hr drive going back and it was almost dark when I left. We just didn't have time and even so, it was running fine when I left.

Either the float has somehow found a bur on the pin or there is just trash in the needle seat. It's an easy fix now. I'm considering taking the carb off and cleaning it out myself if blowing out the carb with compressed air doesn't resolve the issue. I'll have to do this again one day so I agree, I might as well learn now.