Chrysler 75hp '76 Suddenly Stopped

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Shansta

Cadet
Joined
Nov 19, 2012
Messages
12
Hi,

Was on my way out for a fish today and after a few kms my boat suddenly stopped, ended up getting a tow back home.

While waiting for a tow, i tried starting the motor several times, the only time i could get it to start was if I sprayed a fair bit of carbi spray into the carbs, but then it would die. I checked my fuel lines as I thought it was not getting fuel, but when I got home I took of the fuel filter attached to the motor and it was clean and seemed to be receiving fuel from the bubble/line fine.

I took out the spark plugs and they look pretty black, wet and smell like petrol. I am starting to think it may be a problem with the fuel not sparking correctly. I am not sure if the plugs are sparking and do not know how to test myself. So, instead I have taken a few pics of the plugs and was hoping someone could tell me if they look like they are no good, as I am hoping the is the cause of the problem. My motor is a '76 75hp Chrysler.


sparks.jpg

Thanks,
Shannon
 
jerryjerry05

jerryjerry05

Supreme Mariner
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May 7, 2008
Messages
18,075
Re: Chrysler 75hp '76 Suddenly Stopped

Plugs look ok.A little dirty but they should fire.
If it starts or fires with carb spray??
Then you need to do a compression and spark test.
Then start checking the fuel system.
You say PETROL so I'm guessing your not in the the states???Profile,location?
They use ethanol in your fuel?
Check the flywheel key?
 
S

Shansta

Cadet
Joined
Nov 19, 2012
Messages
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Re: Chrysler 75hp '76 Suddenly Stopped

jerryjerry05 said:
Plugs look ok.A little dirty but they should fire.
If it starts or fires with carb spray??
Then you need to do a compression and spark test.
Then start checking the fuel system.
You say PETROL so I'm guessing your not in the the states???Profile,location?
They use ethanol in your fuel?
Check the flywheel key?
Click to expand...


I am in Australia.

They do use ethanol here, I am not sure what the previous own of the motor used but I use the premium fuel with no (i think) ethanol.

flywheel key? Where and what would it do?

:)
 
Frank Acampora

Frank Acampora

Supreme Mariner
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Messages
12,004
Re: Chrysler 75hp '76 Suddenly Stopped

First, buy a compression tester and check compression ratio on all three cylinders. Hard starting or no starting can be a symptom of a damaged piston or two. Anything over 120PSI would be considered good. Anything below 60 indicates possible internal damage.

If your engine is indeed a 1976, it will have a Motorola CD ignition (finned black box) and a distributor.

The plugs, while dirty do not appear fouled. Look at the white porcelain insulator in the center--no carbon bridging or oil fouling. They should fire correctly. HOWEVER: It never hurts to clean them. Also,some plugs are fussy--they will fire in a plug tester but misfire in the engine under compression. So, if cleaning doesn't help replace them with new.

To test for spark, take out all three plugs and ground them against the block. Now, with the ignition key on, very slowly rotate the flywheel by hand. As each plug comes up to fire, you should hear a snap and see a blue spark across the surface of the white porcelain. IF you hear a BZZZZT and see a constant spark, then the Motorola CD box is bad.

Look at the CD wires where they pass under the flywheel. This ignition system was prone to have the wires rise and rub on the underside of the flywheel, shorting out.

Do not use high test fuel. It is simply a waste of your hard-earned money. These engines were never designed for it and it actually can cause more problems than a 10% ethanol fuel. Just use regular 87 octane pump gas with a 50-1 ratio TCW-3 oil.

Check the fuel pump diaphragm and if it is cracked, hardened , or severely wrinkled, replace it. If you find that the diaphragm has cracked and shed some pieces of rubber, remove the carbs and clean them. Put a cheap plastic disposable in-line filter between the fuel pump and carbs. This will stop any crap that the pump may shed.
 
Justinde

Justinde

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Dec 11, 2010
Messages
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Re: Chrysler 75hp '76 Suddenly Stopped

Where are you in Australia- If you are in Sydney I can help with a compression tester;-)
 
S

Shansta

Cadet
Joined
Nov 19, 2012
Messages
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Re: Chrysler 75hp '76 Suddenly Stopped

I took it to the mechanic, after i broke the ignition switch and he fixed the switch and said compression was 145 on all and the reason it stopped was because only 1 cylinder was getting spark.

I just got it home and well it starts but doesnt want to run for longer than 10-20 seconds. When i first started it up it did a huge backfire. So I dont know where to go from here, doesnt seem like he did much.

Here is a video I took just minutes ago.. Chrysler Stops - YouTube

Cheers
 
C

chrome dome

Petty Officer 1st Class
Joined
Sep 24, 2010
Messages
303
Re: Chrysler 75hp '76 Suddenly Stopped

Shansta said:
Hi, I am in Carrum. You?
Click to expand...

near Seymour but have to come down most satdee arvos (like today, fer instance ) to visit the elderly rels,
if you had been close to the northern suburbs may have been able to squeeze in a quick squiz at the donk and stick a spark tester/ comp gauge on it

but Carrum is just a wee bit too far from there,
seems you have it mostly sorted now anyway
 
S

Shansta

Cadet
Joined
Nov 19, 2012
Messages
12
Re: Chrysler 75hp '76 Suddenly Stopped

I think I have found the cause.

I have noticed the last 2-3 times when titling motor into water there has been a small fuel/oil slick on top of the water around the motor. A week or so ago I launched at a different spot and noticed after there was a small amount of (what I thought) was mud coming from the water intake at the bottom.

I started the engine today but could only get it to run when I gave it some throttle (will not idle for longer than 10 secs), it was running ok with throttle. When I went back to the boat 30mins later I noticed that the grey sludge was back, and underneath there was water/oil/fuel mixed.

So my question is, what is it? Here's a pic.sludge.jpg

Cheers
 
S

searay4me

Seaman Apprentice
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Jul 11, 2006
Messages
40
Re: Chrysler 75hp '76 Suddenly Stopped

FYI. I am not a expert.
That said, it looks like you are pulling water from somewhere. I would check/replace all the seals and gaskets in the lower unit.
This will not fix the running problem but I would check the CD first for spark, then think about cleaning/syncing/adjusting/rebuilding the carbs.
 
C

chrome dome

Petty Officer 1st Class
Joined
Sep 24, 2010
Messages
303
Re: Chrysler 75hp '76 Suddenly Stopped

"may" be just unburnt fuel residue as well,
would get that with my sons 120 when it had a problem and wouldn't start on the stand
 
S

Screaming kiwi

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Sep 23, 2012
Messages
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Re: Chrysler 75hp '76 Suddenly Stopped

Hi Shansta, I'm in Sydney and have had that similar oil leak with my 75HP - it was the driveshaft seal. The white sludge looks like the gearbox oil with mixed with water. I was on holiday the temp gauge went nuts and know water was pumping - the seal had popped. I couldn't get the seal so I 'glued' it back in, replaced the oil and it held up. I have a seal kit on order - $40 from the USA - can let you know the guy if you want.
 
S

Shansta

Cadet
Joined
Nov 19, 2012
Messages
12
Re: Chrysler 75hp '76 Suddenly Stopped

Screaming kiwi said:
Hi Shansta, I'm in Sydney and have had that similar oil leak with my 75HP - it was the driveshaft seal. The white sludge looks like the gearbox oil with mixed with water. I was on holiday the temp gauge went nuts and know water was pumping - the seal had popped. I couldn't get the seal so I 'glued' it back in, replaced the oil and it held up. I have a seal kit on order - $40 from the USA - can let you know the guy if you want.
Click to expand...


Hey sorry been on holidays.

Yeh that would be awesome if you could supply his details.

Cheers
 
MickLovin

MickLovin

Master Chief Petty Officer
Joined
Feb 18, 2013
Messages
822
Re: Chrysler 75hp '76 Suddenly Stopped

Hi sorry to remark so late, I have a 1980 model of this motor, that is definately lower unit oil and it sounds like you are dropping a cylinder, which could be a number of things, carbie jet blocked, plug/plugs fowling. I know the manual for this motor is nearly useless for trouble shooting. Firstly you will have to get your lower unit pressure tested to see where the leak is coming from could also be the prop seal but hopefully not. I had a problem with my motor after doing the carbs I had a mechanic come and adjust as I couldn't get the right sttings, he firstly adjusted the throttle arm as it wouldn't start in idle only 1/2 throttle, after adjusting throttle arm which btw wasn't to spec with the cam, he then adjusted carbs. Has been leaking some black oil out but thats is the decarb still going through the motor. Motor wise you need to know all spark plugs are firing for the cost get new plugs, mine were fowled from decarb. Then do all the maintenance you can do, Impellor, fuel system lines etc fuel tank - start here first if it is fuel prob, you can pull ya carbs apart easy and soak in a white bucket with carby cleaner left overnight these are a metal bowl so doesnt hurt them. Also CHECK THERMOSTAT!!! I found mine in two pieces and wondered why it was getting hot and steaming when turned off. my phone number is 0408180727 if I can help
 
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