trusty old merc 1000 ran good but failed and is letting down a hard fought vacation

[fm elliott]

Vacation this year involved a month of building a 30' pontoon boat and fitting a 1970 Merc 100hp (model 1000ss). Finally with 3 days of vacation gone this week. We took her out yesterday, and the boat and motor ran great. Started quick and ran smooth. I noticed a little leaking around the fitting on one of the gas tanks. Today when idled down, she skipped a little and shut off, and hasn't fired since. The tank was down to a couple of inches in the bottom, so I switched to the better of the 2 tanks, still with no luck. The gas line pump up bulb didn't seem to get tight at first, but finaly did in the end . Still didn't crank.

I removed the hood and when facing the front of the motor, saw a rubber hose on the left side, that had disintigrated, and wasn't connected to the motor. this hose is one of 2 or three that loop from the upperr block, to mid then lower block. I'm worried that these are water hoses, and the engine is damaged, although the motor spins fine and isn't locked up. Also I kept a close eye on the water exit port and it had been "peeing" water like it should.

Any ideas to help put this vacation back on track will be appreciated.

Thanks FM Elliott

 

[j_martin]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

Wish I could, but at this time you have both diagnostic maintainance and preventative maintainance to catch up on. Back a month or so ago you should have checked it all out.

A small leak at the fuel tank turns into an air leak into the fuel when running. It can lean out the engine and hurt it very badly. For want of a nail..........

Either water or fuel bleed lines are pretty critical on that engine. Fuel bleed lines broken off could keep it from even firing, so with a bit of luck it can be fixed quickly. Without pictures or more precise description, it's pretty hard to be more specific with help.

regards
John

 

[daveswaves]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

Like John said, hard to tell without pics, however, if it is peeing out where it should then the disintegrated hose is not a water hose, the only hose with water in it comes from the middle of the water jacket at the spark plug cover and runs to the pee fitting. So, that leaves you with vacuum and fuel hoses, either one of which will stop you from running. The hoses are simple to change however a bit awkward. If you have access to an automotive store go and buy a couple of feet of fuel hose the same size and a bunch of small hose clamps then set to replacing each hose one at a time. Pics would help.

 

[j_martin]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

If that's the pulse hose to the fuel pump, it would stop it dead.

Post pictures, we'll help you get fishin' in a flash.

John

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

John and Dave,

Thanks for the responses. I've attached a couple of pics. with a red pointer to the hose in question.

Dave, any chance of a closer peak (at your inline six and rig) shown on your page. My brother and I bought this 1000, in the 80's. The Cobia eventually had to go, and RED 1000 spent several seasons in his barn, 2 weeks ago I mentioned my pontoon and Big Red getting together....so here we are. I was reminiscing this good old motor and he said..." you know that old Merc. in Uncle Charles's Tractor barn...is the twin to Big Red. (Same year and Model).
I'm making calls and Big Red II may be comming my way shortly. I was thinking about a small ski rig, but after seeing yours.....maybe a bass rig instead.
What year did Mercury change from Red to Blue? Yours looks to be a 115 or 150?
Thanks to you both in advance.
Take Care, FM
(SC Farmer/Builder) I'll get aroung to my I-boats profile soon.

 

[daveswaves]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

That looks to be a pulse hose for the fuel pumps, however, I cant be sure so I have asked an expert from another forum to look at your post.

 

[Aqualift]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

I think those are main bearing balance tubes.

 

[CharlieB]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

Agree, balance tubes.

Those fuel pumps are ported directly to the crankcases.

Can't see if those old carbs have a drain plug on the other side bottom. Drawing near the bottom of the tank could have gotten just a bit of water in the carbs and stopped it.

Have you checked for spark to determine whether it is an ignition problem or fuel delivery?

If spark, clean the carbs, if NO Spark, repost and we'll go on from there.

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

I've replaced the hose and the quick connect on the tank end that was leaking a little, but still won't fire. I don't have a light available here, but clipped hemostats to the sparkplug wire and held it about 1/8" from the motor frame but no spark. To make sure, I removed the sparkplug and clipped the wire back on. Clamped it to the (grounded frame) but no spark.

You also mentioned the low point drain on the carbs, so I am posting pics of the port side.

Thanks for your help.

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

here's the pictures

 

[emckelvy]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

Sounds like you need to troubleshoot your no-spark problem. This should help:

MERCURY BATTERY-POWERED CDI TEST FOR DISTRIBUTOR MODELS

This test is for the 332-2986 switchbox used from 1967-1978 on all the inlines.

This test assumes your coil is good (problems with CDI coils are rare).

DISCONNECT BATTERY

1. Turn off ignition;

2. Disconnect all 3 distributor wires on the Port side of the switchbox (and the ?mercury switch? if present);

3. Remove the HV lead from the ign coil to the center of the dist. cap (remember it unplugs from the coil and unscrews from the cap);

4. Reconnect the HV lead to the COIL only;

5. Position the free end of the HV lead approx. 3/8" from ground (block, shrouds etc), and find a way to hold it there;

6. Jumper the brown and white terminals on the dist. side of the switchbox to each other.

RECONNECT BATTERY

7. Check that you have +12V at the red terminal (even with the ign off);

8. Turn on ignition and verify +12V at the white terminal (same side as the red terminal);

9. Ground the black terminal on the distributor side of the switchbox - this should cause a spark each time you touch ground.

If you get spark with the distributor bypassed, and it won't fire with the distributor connected, the trigger is bad.

Fortunately you won't have to replace the entire distributor body because on this style of ign, the trigger is not an integral part of the distributor, you can just unscrew it from the dist body and replace. Down side is, new ones are quite expensive and might be harder to find. Try eBay, there's usually something there. If I recall, this style of trigger is also used on older Mercruisers.

If you get no spark using the test, the switchbox is probably bad. In that case, be sure to double-check for correct power on the switchbox, check all connections, and check the coil's resistance to make sure it's OK.

HTH & keep us posted...............ed

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

I believe that I can follow those directions. I looked at several of your other post, on relating issues, and am inpressed with your advise. I noticed a mercury diagram there, that was simular to yours, and it referred to the Mercury switch as the tilt switch. Is this the same Mercury switch that you are referring to? If I need to bring you up to date on this......

When I took possession of this motor, the tilt trim switch was absent. 2 wires ran from the motor to the transom grommit (black rectangular plate that the hydraulic hoses pass through the transom in) and the " male tips were almost corroded off. When I wired in the new trim/tilt dash switch, I bypassed these wires to the motor and wired the red, green and blue direct. The battery leeds for the tilt trim are also wired directly to the battery. The 2 wires that were in the transom grommit ( both purple i think but faded) are loose on the outside of the motor. I assumed that since I bypassed them they are dead wires now. if not....they've been exposed to water. What do you think?

 

[CharlieB]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

You are confusing the trim/tilt system with the 'mercury' switch used on some models to ground and kill the engine if the BOAT/motor combination is turned over (tilted) too far.

The switch is located near the top front of the motor, black, thermoplastic housing roughly the size of a lipstick tube. One wire connected to the ignition, one wire grounded.

If this switch shorts, the ignition is grounded and no spark. Disconnect and retest for spark.

 

[CharlieB]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

You've proven the fault is with the ignition system, there is no need to mess with the fuel system.

K.I.S.S. principle applies, also, if it ain't broke........

Follow McElvy's directions to the letter to diagnose the ignition.

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

We'll do the test in the morning. (I believe I see the switch in the attached pic.)

Thanks-FM

 

[daveswaves]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

You've proven the fault is with the ignition system, there is no need to mess with the fuel system.

K.I.S.S. principle applies, also, if it ain't broke........

Follow McElvy's directions to the letter to diagnose the ignition.

Agreed, however you do need to re attach that broken hose if you have not done so already. The hose by the way, according to Dr. Frankenmerc, a well respected mercaholic, was an early attempt at pollution control. Previously the bottom bearing carrier was drilled to let the accumulated oil drain to the environment. This particular set up allowed the oil to be re burnt. Later Merc further utilized this excess oil accumulation to lubricate the top bearing with a smaller hose and a one way valve system.

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

Dave,

Good advise, I've replaced all of those old hoses and you were right on the awkward part, (especially on the lowest one). I also replaced the quick connect on the tank end which eliminated the leak and potential of drawing air into the system as John said earlier.

I'm starting the electrical test and will hopefully have a diagnosis shortly.

 

[fm elliott]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

I've run the test and have come up with no spark on either point.

I've confirmed that the coil wire is good.

See the attached picture: the wires feeding the coil are shown with the lower red and green arrows. One goes to the black terminal (upper red arrow) and the other to the box (upper green).

both of these wires are dead when the switch is off, switched or cranking.

Shouldn't there be 12v going into the coil on one of these? If so it looks like my terminal box is bad. by the way.... (can someone tell me what this terminal box is called).

both upper and lower red wires show 12v when switch is off and on.
the upper white wire shows 12v when switch is on.
The lower white shows 12v flicker when cranking (indicating that the alternater is good) fyi the black wire paralleling the white from the alternator, also shows 12 volt flicker when cranking. any help is appreciated.

 

["G"]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

Before you go ANY further do a compression test. All else is futile if that is no good.

The pointer in the picture points to a mercury switch. If you were to tilt the motor up or the motor hit something and it flew up, It would die when the mercury shorted the contacts inside. That's the design and purpose of it. They rarely go bad.

Further, the cracked tubes you point to with that red straw are balance tubes (as already spoken). They drain/draw unused fuel into the crankcase. There are check valves in the block so be aware of that if you try to blow/clear them out. Remember that any air pressure leaks in the crankcase will disrupt "suction" as the piston moves toward TDC. On it's return, it opens the cylinder for exhaust and intake of a fresh load of fuel. (Two cycle operation simplified). Part of that "suction" action opens the reed valves as well. Important stuff to know and remember with two stroke operation/diagnosis.

As for a spark test these old ones were easy to get a test on. Rotate the flywheel and align the timing pointer at 23 degrees (or as posted), turn on the ignition and rotate the distributor quickly toward the WOT position. This will give you a spark and it's a great way to set secondary timing while you're there. Also look for coil/spark plug wire deterioration. If the other rubber is hard and deteriorated, the wires may be as well.

If you have no spark I'd be looking in that distributor cap. They were infamous for carbon build up, rotor corrosion and that carbon brush in the center of the cap gets gunked up and sticks or the spring gets broken.

Hope this helps...

 

["G"]

Re: trusty old merc 1000 ran good but failed and is letting down a hard fought vacati

One more thing I neglected to add... Check the belt on your distributor for checks, wear, deterioration etc. Remove the 5/16 cap screw that holds the cover over the belt and be sure the pointer is aligned correctly.