1977 merc 1500 inline 6 not getting fire

[ventureman]

Hi everyone: Found this forum yesterday. Just bought a 1977 merc 1500 inline 6 a few weeks ago. Mounted on my boat now. Started after about 15 cranks with last week. It would initially backfire but run fine after that on ear muffs. Smooth idling. Started and stop 3 times without any problems.. Now, I could not get it to run. NO SPARK! on all cylinders. Hook up voltmeter
from red to white terminal and it is showing less than 9 volts. Could be problem with harness, battery, or cables, but I doubt it even though I am supposed to get at least 9.5 volts to start. Checked switchbox, seems ok, not sure about trigger, rectifier seems ok. Suspect coil but not sure. Also starter bendix sometimes stick to flywheel, not sure if I am getting enough juice to fire, but it does turn pretty fast. My external harness however is old and warped. I retaped with electrical tape. Previous motor was a 1978 merc 1750 V6 thunderbolt ignition. Starter seems to be the same size. Could replace that if necessary. Rectifier and solenoid seems compatible also. Wiring harness is not though. I may add I am using the key from the merc 1750 to start the 1500 since it didn't have one. Haven't hook up controls yet. Was thinking about using the quicksilver control from the 1750 instead of the mercontrol from 1500. Is that possible or hard to do. Also, if my switchbox is bad, can I use the switchbow from the 1750. I know it is different but I can rewire them. Where should I start???? I know I should check my harness, starter battery or cables first, but I seems to rotate just fine except for sticking to the flywheel. Grounding problems. Please help! Thanks

 

[Chris1956]

Re: 1977 merc 1500 inline 6 not getting fire

Venture, A 1977 Merc 1500 has a distributor, and a single switchbox and coil. The wiring is compatable between the 175 and the 150 motors, even if the plugs are different. On the 1500, you should have +12V on the white wire and red wire on the switchbox, measured to ground. The stator and rectifier are independent of the ignition system.

I recommend you make sure you have +12V on the white wire (ign key), and +12V on the red wire (battery), and the battery cables are good, clean and tight one each end. Pull the dist. cap and clean it as well as the rotor. The rotor is not removeable and costs ~$200, so do not break it. Check the plug wires for acring to ground, especially num 6.

 

[OldMercsRule]

Re: 1977 merc 1500 inline 6 not getting fire

Off topic thought (fer yer cornsideration)! That 1500 is much less powerful then the 1750 is/was. (Much more then a 25 hp difference or 14% less power then the 175 hp through the entire power range: IMHO). The inlines must turn the high RPMs, (expecially the 1500s) to develope their Power where the larger cubic inch and heavier V-6s have much more snot at low and mid RPMs. Mercs have always been underrated, but the 175 hp V-6 is not working very hard to generate power vs the smaller lighter tweaked 1500 inline6, (which needs to be detuned, especially: the timing). The 1500 hp pistons were a bit tweaky cornpared to the 1400 or 140 or (post 1982 115 which is the same basic engine as the 1981 140 was). If yer runnin' a heavy boat jus' thought you would want to cornsider the swap yer doin'! Inlines are great fer light hulls on fresh water. Respecfully, JR

 

[Jimmy70]

Re: 1977 merc 1500 inline 6 not getting fire

Sure sounds like you have a bum battery to me.
Jimmy70

 

[ventureman]

Re: 1977 merc 1500 inline 6 not getting fire

Took the distributor cap off, clean and reassembled. Same results, NO SPARKS. Not sure if points are good. Does anyone know where I can get a replacement dist. cap at a reasonable price? Seen some 6 wire cap for OMC for less than $15.00, but merc is more than $100.00. Will have to check with a spark gap tester. Voltage between white and red terminals is 12.55 . Battery at 12.69 Red and Green at 12.69. White and Red 9.00 volts while cranking. It is pointing to problems with harness, key switch, starter, battery cables or battery. Will try replacing starter tomorrow. If that doesn't do it, I might have to check the trigger, but I do not have a direct voltage adapter with my multi-meter.
Off subject, my boat is a 1978 19'er Venture Phase V , really heavy. I know a merc 150 might be underpowered, but that all I could do without spending a lot of money. Horsepower used to be rated at the powerhead, now it is rated at the prop.So really, it is at best, a 125 HP motor. My biggest concern is getting it to plane with the smaller 17 pitch ss prop. Had a 19 pitch Laser II on the 175. Had a 21 that was sluggish on holeshot. FYI, I locked up the motor while running wide open. Not something you want to see or hear.
Back to subject, let's hear your opinion, starter, trigger, switchbox , coil, distributor???? Thanks!

 

[Chris1956]

Re: 1977 merc 1500 inline 6 not getting fire

Venture , Clams Canino posted an ignition test for the distributor mercs. See if you can locate it in the FAQ or vai search.

 

[ventureman]

Re: 1977 merc 1500 inline 6 not getting fire

First of all, thanks to everyone that replied. Update: Found out today that the stator wire was the culprit. It was rubbing against the flywheel causing it to ground. Rewired that and it fired up. Put the motor in a tub(35 gallons) was able to fire up but did not see any water coming out of the pee hole. I shut it down after 10 seconds. Tried restarting but have hard starting problems. I think carbs needs adjustment but would like to see water coming out of the pee hole before I spray some cleaner in it. My question is, should I use the tub or ear muffs(I do have one)? Never have much success with ear muffs. True test would probably be running the motor on the lake. On a seperate subject matter, if I am running a 40 horse motor wide open, if it suddenly wants to bog down, would it be carb or fuel starvation or something else? Throttle back at mid range and it would run just fine. Thanks again.

 

[Chris1956]

Re: 1977 merc 1500 inline 6 not getting fire

Venture, It is hard to believe that your stator caused the spark issue. Thes systems are pretty isolated from each other.

As for running the motor, either flush device or tub is OK. Muffs are more convenient and less messy.

On that 40HP, suspect the fuel pump.

 

[ventureman]

Re: 1977 merc 1500 inline 6 not getting fire

Chris1956, the wire has been spliced by the flywheel. Exposed copper wire making contact with flywheel. I will check the fuel pump on the 40. Thanks

 

[ventureman]

Re: 1977 merc 1500 inline 6 not getting fire

Hi guys: Thought my problem was solved but now I have a bigger problem. Tried to start my motor, would only turn over with no sparks. Noticed the 2 lead wires are beyond bad with only an inch of wire left with very few strands of wire left in it. At the stator's terminal end, hairs of wire were touching the motor, which I believe is grounding. Really don't think I could rewire at all. Probably will have to be replaced. My questions are:
1. Is the stator attached to the flywheel in one piece?
2. Can the stator lead wires be replaced? Only 2 wires. Are those wires glued in or something?
3. Is it possible to replace it with the stator from my 175, even though it has six wires(I think)?
Did a compression test today, they range from 120 to 122 on all 6.
Did noticed today that the rotor on my distributor is NOT making even contacts with the side points. Heavy copper pittings(dust) from the cap. Cap itself looks to be good shape, no cracks.
Please help!

 

[inline_1350]

Re: 1977 merc 1500 inline 6 not getting fire

I have a 71 Merc 1350 that had bad stator wires. I was able to remove the top housing and remove the eight or so bolts on top of the flywheel to remove it. Didn't need a puller in my case. I'm a auto tech with 30 years of experiance and specialize in electronics. I found it fairly easy to slowly remove the filler around the stator wires and gently pull on them at ther same time at the point where they entered the stator. I gently kept working them one at a time untill I got to the point to which the wires pulled down just enough to where they were attached to the stator windings and just enough to work with them with out them even rubbing together. Mercury used a woven wire and I soldered in some new solid copper wires using the inside of a standard yellow butt connector (the metal part only) I cut it in half to use on each side to crimp the connections together before soldering. A good shrink tube to seal it back up I made sure they were in the clear, lots of room. Yesterday I brought it back to life after 13 years. OMG it sounds awesome. It had a new powerhead built for it some 16 years ago suposed to be built by a inline merc guru. never got used much as in not really broke in yet even. I'll be taking care of that now..

 

[Chris1956]

Re: 1977 merc 1500 inline 6 not getting fire

Venture, Your '77 has a battery-driven CD ignition. Your stator plays no part in the ignition system. Disconnect it if you wish.

Make sure you have +12V on the red and white wires attached to the swutchbox, when the ignition key is on. If you have no spark, it is likely the switchbox is bad or the trigger in the dist' is bad. The coil is less likely to be bad, but it happens. Check the motor wiring harness for shorts, and chek the plug wires for arcing.

 

[Laddies]

Re: 1977 merc 1500 inline 6 not getting fire

On your 1500 the stator only charges the battery here the system test from CDI

 

[ventureman]

Re: 1977 merc 1500 inline 6 not getting fire

Update: After reading Chris' post that my stator has nothing to do with ignition for my model year, I decided to recheck my wiring harness(per Chris).
I remove the cover to the control box, check the switch for loose connections, etc, Connections were good but looks corroded. However, a foot down the box, saw some cracks from the rubber insulation. Decided to take it apart. Orange wire has rotted out. White wire is broken. They rest are ok but in bad shape. Put 2 wires on those and the motor fire up. Guess it was
my harness all along. Call a starter and generator place this morning, they say they can rebuild the stator, if they can't, it will be shipped to be rebuild.
Thanks again everyone, especially to Chris. Couldn't have done it without this forum.