Sometimes it cranks and sometimes... Not so much...

[TBarCYa]

I'm having a wierd problem with my 1975 Merc 888. The past two time it's been out it has started with no problems at the dock however after running for a while then shutting it down, it seems like it's harder for the starter to turn it over. It sounds like the batteries are low but it will crank for long periods of time and then start cranking faster and fire up. Sometimes, the solenoid won't click and it won't turn at all but if I jump the solenoid, it cranks as described and fires.

I've got the batteries on the charger now just in case they actually are low but does anyone have any other suggestions for what it may be? Perhaps the slow cranking is a different problem than when it doesn't crank at all but both occur only when the engine is up to temp.

Thanks.

 

[Haut Medoc]

Re: Sometimes it cranks and sometimes... Not so much...

I would clean all of the electrical connections & see if that helps......
If the battery wires get at all hot, it is time to repalce them....
Quite often they look good on the outside, but are going bad on the inside....​

 

[Nova II 260]

Re: Sometimes it cranks and sometimes... Not so much...

Check your timing advance, too much will be hard starting when warm.

 

[Haut Medoc]

Re: Sometimes it cranks and sometimes... Not so much...

One other thing I would do is pull the plugs & spin the engine to make sure you do not have a failing manifold/riser.....​

 

[TBarCYa]

Re: Sometimes it cranks and sometimes... Not so much...

HM,

How do I tell from turning the engine without the plugs if the manifold or riser is bad? Is there a noise or something else to look for?

 

[marunr]

Re: Sometimes it cranks and sometimes... Not so much...

I believe he's referring to the fact that if your manifolds/risers are bad you could be getting water in the cylinders on top of the pistons, which would cause the engine to barely turn over if at all. If water comes out when you turn it over with no plugs, you'll see.

 

[Haut Medoc]

Re: Sometimes it cranks and sometimes... Not so much...

I believe he's referring to the fact that if your manifolds/risers are bad you could be getting water in the cylinders on top of the pistons, which would cause the engine to barely turn over if at all. If water comes out when you turn it over with no plugs, you'll see.

Yup, just something to check, that costs nothing but your time to do....

 

[TBarCYa]

Re: Sometimes it cranks and sometimes... Not so much...

Sounds like a plan. I'll definitely check that as well as the battery cables.

 

[murphini]

Re: Sometimes it cranks and sometimes... Not so much...

wow. Had almost exactly same problem yesterday with my 89 VIP Cobra 302. It was 100 degrees outside, we were wakeboaring and all of a sudden had the same hard cranking problem. Killed the battery. Then replaced the battery and still had the hard cranking problem

Today, went out to troubleshooot and it started right up. I thought I had a case of mortal vapor lock.

Yesterday my black wire from the battery was very hot, in fact, I burned my thumb when I checked the connection.

So is it possibly needing new battery wires or was it vapor lock?

Thanks in advance...sorry to Thread Jump...

 

[Haut Medoc]

Re: Sometimes it cranks and sometimes... Not so much...

Any time a wire gets hot like that, it is due to resistance.....
I would check to see if you have any signs of water intrusion......
Water can seep past the rings when cooled off....
Not saying this is your problem, but it does not hurt to check...
Advanced timing can make it hard to start when hot as well.....​

 

[TBarCYa]

Re: Sometimes it cranks and sometimes... Not so much...

Any ideas on my problem where sometimes the solenoid doesn't tell the starter to turn? It behaves like it's in gear but that doesn't appear to be the problem. I can turn the key and move the throttle and it never tries to start. Then on one attempt it'll crank and start and if not, I jump the solenoid and it starts right up. This also only appears to happen when it's hot.