Author Topic: Mercruiser 140 difficult to start when cold [FINALLY, SOLVED!] (Read 49206 times)

Plugcheck · « **Reply #40 on:** June 29, 2015, 05:09:42 PM »

Offer still stands, just trying to help. You can call me when you're looking at it, or shoot me a text/pic.

Neutron68 · « **Reply #41 on:** July 03, 2015, 11:50:41 AM »

Today, the mechanic who lives here at the lake, finally had time to come look at the carburetor. He got the top off said that the linkage for the accelerator pump was connected, but that no gas was being pumped when the accelerator pump plunger was moved. He just took the carburetor off and back to his shop, to work on there. He thought that there must be some obstruction in the passage from the pump reservoir to the carb throat.
On Tuesday, I got a 2-barrel carburetor rebuild kit so we're covered in case one of the parts in the carb is missing or bad.

Eric

Neutron68 · « **Reply #42 on:** July 04, 2015, 11:47:57 AM »

We have a winner to the guessing game! thedeuceman

The ball bearing below the accelerator pump was MISSING.

With a ball bearing in place, the accelerator pump is pumping correctly!

Happy Day!

Happy Independence Day everyone!

Plugcheck · « **Reply #43 on:** July 04, 2015, 12:44:20 PM »

Good to hear all is well. Fully rebuilt and properly rebuilt are not always synonymous terms. Enjoy your boat and be safe this 4th, Michael.

Neutron68 · « **Reply #44 on:** July 04, 2015, 04:15:03 PM »

Maybe I can't declare this 100% solved?

We took the boat out for a test run this afternoon and it started easily and ran ok, but it still has the death-on-throttle-punch syndrome.

Kevin, the lake mechanic that just worked on it said he thought that there should be more travel of the accelerator pump linkage (or arm).
Is there a way to adjust the amount of travel of the accelerator pump linkage?

Rich_V174SS · « **Reply #45 on:** July 04, 2015, 06:32:23 PM »

Slow auto-timing advance can do the same thing if the centrifugal cam in the distributor is sticking.

Jason · « **Reply #46 on:** July 04, 2015, 09:55:31 PM »

Quote from: Rich_V174SS on July 04, 2015, 06:32:23 PM

Slow auto-timing advance can do the same thing if the centrifugal cam in the distributor is sticking.

For the record, my 140 did exactly as Rich stated.

Neutron68 · « **Reply #47 on:** July 07, 2015, 01:29:16 PM »

Quote from: Rich_V174SS on July 04, 2015, 06:32:23 PM

Slow auto-timing advance can do the same thing if the centrifugal cam in the distributor is sticking.

Thanks for this info Rich.
Is this easy to get to?
Simple cleaning/lubrication or replacement?

Rich_V174SS · « **Reply #48 on:** July 07, 2015, 08:01:39 PM »

Take the distributor cap off, take hold of the rotor and it should easily turn about a quarter inch in one direction and spring back when released. If it does not then it could be sticking. If you pull the rotor off the top of the shaft you can put some penetrating oil down the center of the shaft, let it soak in for a while then try the rotation test again.

Jason · « **Reply #49 on:** July 07, 2015, 09:34:38 PM »

Mine were actually stuck out or fully advanced. I believe there are two cams that expand outward.

Neutron68 · « **Reply #50 on:** July 09, 2015, 10:49:31 AM »

Quote from: Rich_V174SS on July 07, 2015, 08:01:39 PM

Take the distributor cap off, take hold of the rotor and it should easily turn about a quarter inch in one direction and spring back when released. If it does not then it could be sticking. If you pull the rotor off the top of the shaft you can put some penetrating oil down the center of the shaft, let it soak in for a while then try the rotation test again.

Oh, I would love it, if that's all I need to do!

I'll report back after I get a chance to try that.

Eric

Neutron68 · « **Reply #51 on:** July 19, 2015, 10:34:50 AM »

Quote from: Rich_V174SS on July 07, 2015, 08:01:39 PM

Take the distributor cap off, take hold of the rotor and it should easily turn about a quarter inch in one direction and spring back when released. If it does not then it could be sticking. If you pull the rotor off the top of the shaft you can put some penetrating oil down the center of the shaft, let it soak in for a while then try the rotation test again.

I did this yesterday. The shaft behaved as you described. It rotated about 1/4 inch and snapped back. I sprayed penetrating oil in there anyway.
I ran it again several hours later and it still had the throttle-up-die syndrome.

Of note, I needed to pump the throttle lever 5-10 times before the engine would start easily. It makes me wonder how efficiently the accelerator pump is pumping?

Neutron68 · « **Reply #52 on:** July 21, 2015, 11:39:47 AM »

The lake mechanic that put the accelerator pump check-valve ball bearing in for me, said he thought that there should be more travel of the accelerator pump linkage (or arm).

With the throttle lever, the 12 o'clock position is neutral, and the 9 o'clock position is full throttle.
I've noted that the throttle lever doesn't change the throttle rate until it gets to about the 10 o'clock position.
Is that normal? It's terribly non-linear!

Maybe this non-linear behavior of the throttle lever is affecting the accelerator pump?
So that the pump doesn't pump until the throttle lever gets to the 9 o'clock position?

Does it sound like the throttle cable or linkage is out of adjustment?

Eric

Jason · « **Reply #53 on:** July 21, 2015, 12:02:52 PM »

Going way back to the orignal post I found this:
"updated electronic ignition distributor body and cap."

Is this the Petronix unit? After I installed this in my distributor I had all kinds of issues? Took it out and went back to points and all was well.

Jason · « **Reply #54 on:** July 21, 2015, 12:04:45 PM »

Also, did you set the idle mixture screws on the carb? That could also be your problem.

Neutron68 · « **Reply #55 on:** July 21, 2015, 05:03:30 PM »

Quote from: Jason on July 21, 2015, 12:02:52 PM

Going way back to the orignal post I found this:
"updated electronic ignition distributor body and cap."

Is this the Petronix unit? After I installed this in my distributor I had all kinds of issues? Took it out and went back to points and all was well.

Also, did you set the idle mixture screws on the carb? That could also be your problem.

Yes it is a Petronix electronic ignition kit. It runs fine - no problems at any engine speed.
When the boat had the oil-using 120 engine in it, I installed the Petronix electronic ignition and a new distributor cap. The 120 started and ran fine - no problems at any engine speed. When the engine was changed to the 140 engine, the new Petronix kit and new distributor cap were moved to the 140 engine.

Yes, I adjusted the idle mixture screws, following the procedure in the service manual (in the water, in forward gear, at idle speed). It idles pretty smoothly now.

Jason · « **Reply #56 on:** July 21, 2015, 09:34:05 PM »

Did you use 120 or 140 wiring harness? I believe 120's use an external resistor which you would have bypassed with the Petronix. The 140 uses a resistor wire. So if you are using the 140 wiring you might not be getting a consistent 12V to the coil or module. Just another thing to check.

Rich_V174SS · « **Reply #57 on:** July 22, 2015, 06:29:25 AM »

Quote

Did you use 120 or 140 wiring harness? I believe 120's use an external resistor which you would have bypassed with the Petronix. The 140 uses a resistor wire. So if you are using the 140 wiring you might not be getting a consistent 12V to the coil or module. Just another thing to check.

Just to add...
Having a Pertronix sensor has no bearing on whether the engine harness has a ballast resistor or resistor wire. That depends on the ignition coil and it would be the same coil for either. The Pertronix will work with either or none at all. BUT, if you have a Pertonix you have to tap power before the resistor (or resistance wire) for it to operate correctly, not at the coil itself.

Neutron68 · « **Reply #58 on:** June 06, 2016, 05:51:44 PM »

This throttle-kill problem is still not solved....

First, an update.

Fall 2015: I took the boat back to the the mechanic that swapped the engine from the 120 to the 140.
He found that the ball bearing that my lake mechanic had put in (in July 2015) was the larger size ball bearing from the carb kit and it was jammed in the fuel channel between the accelerator pump and the fuel bowl - and would not come out!
So, he got a different used carb and put it on the engine. He test started it and then winterized the boat.
He didn't test it to see if the acceleration problem was still there. I WISH HE WOULD HAVE TESTED IT MORE!
He told me to give him a report in the spring (2016) when I started it for the first time of the season.
So, I towed the boat back to the lake and parked it in the garage for the winter.

Spring 2016: May 15, I rolled the boat out and gave it a test with water muffs in the driveway.
It started much easier this time, but the engine still kills if you increase the throttle quickly.
I was alone when I test started the boat, so I did not get a look at how much gas was getting squirted down the carb throat, when the throttle lever was pumped. Since it started much easier than last year at this time, I would guess that some gas is getting squirted by the accelerator pump, now.

The I shot a video to demonstrate continued throttle-kill for the mechanic.
https://www.youtube.com/watch?v=_MF2sJg_wqU

I sent him the link to the video and 2 weeks later he finally responded (through Dan Luke) that he doesn't know what else to do about it, and advised buying a new remanufactured carburetor.
I personally don't think he did enough diagnostic testing to determine that the carb is definitely the problem, and he doesn't seem willing to do more work on it.

On Sunday, I noted that the best setting for the idle set screws was for the rear screw to be 100% seated and the front screw to be 1/2 turn opened.
I'm not sure if that indicates anything?

So, is this definitely a carb problem? Or could it be related to the carb linkage levers or the Petronix electronic ignition?

Should I send this current carb to The Carburetor Shop in Maplewood to be reworked, or buy a new remanufactured carb from somewhere?

Eric

Rich_V174SS · « **Reply #59 on:** June 06, 2016, 06:19:13 PM »

Sounds to me to either be a starvation problem or a spark advance lag. Make sure your advance in the distributor isn't bound up and moves freely. Also (mentioned before) check that your Pertonix is connected to your ignition source BEFORE your ballast resistor or resistance wire and not at the coil or else it could be underpowered.

Your idle mix screws could also be too lean and should be adjusted with the boat in the water for proper back pressure. If you find you're having to set them almost closed your carb could be flooding at idle, no fuel should be dripping from from the venturies when the throttle plates are closed at idle. Dripping fuel means too high a float level or a leaking inlet needle valve.