Miss, Bog, and dead in the water again...

[James D. Evans]

MCM 140, new plugs, wires, points, condensor, coil, filters and water canister filter, dwell at 32.5, timing at 6 BTDC, three weeks ago. Carb rebuilt by boat shop and reinstalled at the same time as fuel pump filter, water filter, new fuel line; a month and a half or so ago. Also checked vent and anti siphon valve at this time.

First trip out after tune up, 3 weeks ago, ran flawlessly for 3/4 of a tank. died leaving the dock heading for the trailer. Had to pump and pump and pump to get started. Would only run around 1500rpm any less, would die, but revved fine.

Didn't make it out 2 weekends ago, dropped the lower to replace impeller and housing.

Last Sunday, rechecked dwell-OK, rechecked timing, was off by 1 degree and adjusted it. Checked oil, which was clean. Emptied water separator, topped off the fuel and headed to the h20. Ran with no sign of issues for about 30-45 mins, started lightly missing till it bogged down to 25-2600rpm, some surging wanting to take off but couldn't. Jumped up 1 time for two or three minutes, but back to the bog down after that. Wouldn't take any throttle at all past around 25-2600, backed it down to 2000, limped it to the ramp. Pulled it to neutral and, yep...dead in the water. Once again pump and pump (finding the sweet spot) to get it to start, would run once again at 1500, but no less. Got her home, checked the filters...nothing. one or two specs on both. I have the old school fuel pump, filter on top, found it odd that no fuel spilled when I took the cap of it off. Not a drop. Once it decided it wanted to idle, I rechecked dwell and timing, which were dead on. Upon revving up on the trailer, it didn't rev or sound right.

Fuel Starvation? The pump looks to me to be the original, boats a 1984. Only thing I can see being left since everything else is been gone thru...

 

[Volphin]

Re: Miss, Bog, and dead in the water again...

I would certainly look very closely at the fuel pump and signs of water contamination in the tank...

 

[harleyman1975]

Re: Miss, Bog, and dead in the water again...

If not the pump then maybe the pick up in the tank is plugged/plugging up. Happened to me this spring.

 

[bonzoscott]

Re: Miss, Bog, and dead in the water again...

It seems to run good for a while, then peters out. If you can recreate the situation, when you said you have to pump and pump the throttle to get it stated, look down the throat of the carb and make sure it's squirting good supply of fuel while pumping. You have to do this "When it dies" on you. If you rule out the fuel, then it may be the coil. You need to check for good spark when it dies.

 

[James D. Evans]

Re: Miss, Bog, and dead in the water again...

When I dumped the water separator sunday, I dumped it into a jar to see if it had any water in it. Had forgotten about it, and checked it last night, and it didnt. however when I shook it, I noticed all kinds of stuff swirling around in it.

 

[NHGuy]

Re: Miss, Bog, and dead in the water again...

Then you ought to clean out the tank, change the fuel filters and try to run it. The way it's been running sounds as if the carburetor is still working correctly.
Swirling junk in the fuel ain't a good thing.
If you have to save the fuel you'll have to polish it. You do that by repeatedly filtering it til it's clear. What a PITA. At first you can just put it through a mesh filter to grab the bigger debris, then use a real fuel filter as a final cleanup.
If you can get the tank empty go in through the sender hole and wipe the last little bits out of the tank bottom. I'd use a piece of fuel/oil absorber pad on the end of a stick or in one of those reaching-tool grabber things. After that maybe blow in there to loosen any bits that stick. Do this outdoors, with the battery disconnected and wearing appropriate gloves and other protection. Keep a fire extinguisher on hand too.
Good luck, I hope your tank has access.

 

[boozer1966]

Re: Miss, Bog, and dead in the water again...

I have an '84 MCM 140 with similar problem. Runs fine for 30-45 minutes then goes all haywire. I have replaced the entire fuel system from the filler neck to the carb with the exception of the tank which I visually inspected and found to be clean.

I think it's an electrical issue. I have replaced plugs, wires, cap, rotor, added electronic ignition. Still the same problem. I just replaced the distributor and set timing. It's the best running boat on muffs this side of the Mississippi. It may be a bad ground, but I have traced everything I can find. It almost seems heat related since it runs well for 30-45 minutes on the water. I'll let you know if the new distributor helps.

 

[boozer1966]

Re: Miss, Bog, and dead in the water again...

I should have mentioned that I replaced the coil too.

 

[Mbrgr1]

Re: Miss, Bog, and dead in the water again...

MCM 140, new plugs, wires, points, condensor, coil, filters and water canister filter, dwell at 32.5, timing at 6 BTDC, three weeks ago. Carb rebuilt by boat shop and reinstalled at the same time as fuel pump filter, water filter, new fuel line; a month and a half or so ago. Also checked vent and anti siphon valve at this time.

First trip out after tune up, 3 weeks ago, ran flawlessly for 3/4 of a tank. died leaving the dock heading for the trailer. Had to pump and pump and pump to get started. Would only run around 1500rpm any less, would die, but revved fine.

Didn't make it out 2 weekends ago, dropped the lower to replace impeller and housing.

Last Sunday, rechecked dwell-OK, rechecked timing, was off by 1 degree and adjusted it. Checked oil, which was clean. Emptied water separator, topped off the fuel and headed to the h20. Ran with no sign of issues for about 30-45 mins, started lightly missing till it bogged down to 25-2600rpm, some surging wanting to take off but couldn't. Jumped up 1 time for two or three minutes, but back to the bog down after that. Wouldn't take any throttle at all past around 25-2600, backed it down to 2000, limped it to the ramp. Pulled it to neutral and, yep...dead in the water. Once again pump and pump (finding the sweet spot) to get it to start, would run once again at 1500, but no less. Got her home, checked the filters...nothing. one or two specs on both. I have the old school fuel pump, filter on top, found it odd that no fuel spilled when I took the cap of it off. Not a drop. Once it decided it wanted to idle, I rechecked dwell and timing, which were dead on. Upon revving up on the trailer, it didn't rev or sound right.

Fuel Starvation? The pump looks to me to be the original, boats a 1984. Only thing I can see being left since everything else is been gone thru...

Check your fuel line too, there was a thread about ethanol deteriorating the inside coating of fuel line, clogging it up, other than that something in the tank clogging the inlet.

 

[James D. Evans]

Re: Miss, Bog, and dead in the water again...

Check your fuel line too, there was a thread about ethanol deteriorating the inside coating of fuel line, clogging it up, other than that something in the tank clogging the inlet.

i replaced the fuel lines at the same time that I replaced the filter, added the separator, and installed the carb. That was about 2 months ago. I replaced the fuel sending unit the end of July because it was inop. Tank looked clean. Keyword looked. The stuff swirling around in the jar was very hard to see, like small white hairs. Didn't see them at first, when i was moving it out of the light I saw them, and lots of them. Prob wouldn't have seen them in the filter when I took a look see at them sunday. But they did come out of the separator which is before the pump.

Should there have been fuel that spilled out when I took the filter out of the fuel pump with the old style, filter on top, pump? I leaked not a drop, and I can't remember exactly if it did or didn't when I changed it 2 months ago. Seems like it did...I'm gonna check the anti siphon, vent, and inlet this weekend. The vent, should I be able to move air thru both ways or does it have a check valve permitting air travel one way?

 

[James D. Evans]

Re: Miss, Bog, and dead in the water again...

I have an '84 MCM 140 with similar problem. Runs fine for 30-45 minutes then goes all haywire. I have replaced the entire fuel system from the filler neck to the carb with the exception of the tank which I visually inspected and found to be clean.

I think it's an electrical issue. I have replaced plugs, wires, cap, rotor, added electronic ignition. Still the same problem. I just replaced the distributor and set timing. It's the best running boat on muffs this side of the Mississippi. It may be a bad ground, but I have traced everything I can find. It almost seems heat related since it runs well for 30-45 minutes on the water. I'll let you know if the new distributor helps.

Wow. I have done a ton of research. I don't post till I come up empty handed. Have you disconnected the tach to see if it goes away? Read some info regarding it causing problems, and my tach reads outta whack at times. Sometimes on the muffs and a time or two in the water. However when the boat starts acting up my tach reading seemed normal, or atleast close to normal, not way high like it has done a couple of times.

 

[Mbrgr1]

Re: Miss, Bog, and dead in the water again...

"Should there have been fuel that spilled out when I took the filter out of the fuel pump with the old style, filter on top?"

On my old 165 6cyl, I get quite a bit of fuel when changing filters with the upside down pump, if you think about it, where would it go? It's uphill in both directions. The other possibility is it's sucking air somewhere, but I would think that would show as a leak too.

Maybe rig up a test fuel tank and run it on that to prove or disprove the clogged pickup theory in the main tank?

 

[OldNBold51]

Re: Miss, Bog, and dead in the water again...

the test fuel tank is pretty easy to make. Take a 1 gallon plastic jug with a working cap. buy 36" or so of fuel line in the size needed to hook to the carb fuel inlet. Using a drill bit slightly smaller than the OD of the fuel line, drill a hole in the jug's cap. Force the fuel line thru the hole with 1" exposed. fill jug with gas, tighten the cap. This should work like a gasoline IV.

 

[harleyman1975]

Re: Miss, Bog, and dead in the water again...

Just a thought did problem show up after you replaced lines or before? Possible that you have lines reversed?

 

[James D. Evans]

Re: Miss, Bog, and dead in the water again...

Old pump was weak, didn't meet spec on pressure test. Replaced it. Runs much better now, but still starts missing or cutting out after 45 mins. Dropped it off at the shop this morning for winterization. There gonna take a gander at it. Said possibly worn dist gear or resistance wire to coil. Will post back with there findings.

There findings... :facepalm: 0 compression on #3, the others were 140, 125, and 125, maybe not in that order. $200 tear down and I should know if its just a valve, bad piston, etc by the end of the day.

 

[bonzoscott]

Re: Miss, Bog, and dead in the water again...

Is it a fiberglass tank? small white hairs? I'd be suspicious of shop and compression test. If you didn't do the test yourself - Zero compression in one cylinder don't run good for 45 minutes.

 

[Walt T]

Re: Miss, Bog, and dead in the water again...

Sounds like vapor lock to me. Try running with all covers off the engine blowers running see if it makes any difference. Not running hot is it?

 

[James D. Evans]

Re: Miss, Bog, and dead in the water again...

Turned out to be a valve, it was tuliped and the seat was burnt out. Only use for the head now is as a anchor. The hairs I think may have been in the jar before I dumped the filter, just pulled it off the shelf and may not have been clean. It is not running hot, and I had the hatch open and there was no change in how it ran/wanted to run.

Luckily the shop had 2 take off heads. They sent one to the machine shop.

Funny thing is, I was out on the water Sunday running 40mph, but after it warmed up, I throttled back to idle for a no wake zone and it died after about a minute It wouldn't idle less than 1200. Hard restart, then put into gear it would just die. Now I say it ran good, but I just bought the boat in July. So I'm not sure how it was supposed to run. Always started right up, but have been chasing a slight miss since middle of august. The miss was always later in the day, after I have burnt over a half a tank or so. I think it was the ole weak fuel pump that did me in. Ill ask the shop there thoughts when I get the call.