Starts and dies problem

[TuffleHunden]

Could someone try to help me please? I have a 1996 Volvo-penta 5.0FL engine and I have a problem that I just cannot tract down. It will start and when I let the key go to run it will die. It will turn over and actually start every time then when I release the key to run it dies. I have replace the Ignition switch, Kill switch, starter, starter relay, coil, distributor cap, rotor, plugs and wires, I have tested just about everything with a probe light as suggested in just about all forums everything seems to check out properly. I checked with a marine mechanic and he requested that I use a hot wire from the battery to the coil + side and see if that fixed my problem. I did and it would not even start. took the bypass off and it started right up but dies when I released the key. I have checked all fuses and in-line fuses and all seem to check out. I have put a test light on the +side of coil and turned key on and I get no light. I have checked the main harness and the one of the big brass pins has power. I have also replaced the two 50 amp circuit breakers. Has two new batteries and a new battery switch. Could someone maybe tell me what I am missing Here as to what to check next? Also could it possibly be the neutral safety switch in the throttle causing this? I sure would appreciate a little help if someone would be so kind. By the way the boat is a one owner, but has just been sitting or stored for a few years. Up until this problem when first started to get boat back in shape it ran fine. Now it's like Murphy's law "What Now".

 

[kelleyja]

Re: Starts and dies problem

It will start and when I let the key go to run it will die.

How many seconds pass before it dies, after you release the key? Fuel pump is temporarily powered by the start circuit, when cranking.

 

[hall832]

Re: Starts and dies problem

Did you replace the key switch?

 

[skydiveD30571]

Re: Starts and dies problem

The neutral safety switch prevents the starter from engaging at all, so that's not it. Your fuel pump is powered by the ignition circuit during starting, then by the alternator once running. I'd be checking for power at the fuel pump both during cranking and right afterwards.

 

[Taz59]

Re: Starts and dies problem

Check this out
http://forums.iboats.com/mercruiser...ting-your-engines-starting-system-167035.html

 

[TuffleHunden]

Re: Starts and dies problem

Hello I want to thank you for the replies and I a confused. One statement that was made was that if the neutral safety switch was bad that it would not even allow to start so that was not my problem. In the wiring diagram I have tested all and it stated that it was 1 of 3 things that could be wrong and one of those was the neutral safety switch! could someone clear my head for me please on this topic.

 

[skydiveD30571]

Re: Starts and dies problem

The neutral safety switch will not let the engine turn over, let alone start and run until you release the key.

Do you have a link to this manual? Wording can be very important. Did you check for power at the fuel pump during and after cranking? This is not an uncommon problem, and can generally be traced to a diode in the wiring between the alternator and fuel pump.

 

[TuffleHunden]

Re: Starts and dies problem

HI skydive, It was a diagram from TAZ59 which is shown in this thread. Also I do not have an electric fuel pump. But I have checked the pump by disconnecting the fuel line from carb and it gushes through the line. I have additionally ran continuity test and I think I am down to the neutral safety switch and or the electronic module in the distributor. It gets good voltage when I turn the key to start and acts that it wants to start and when I let the key go it dies. Not sure where else to check and do. Hope you can steer me in the right direction. Thanks

 

[dypcdiver]

Re: Starts and dies problem

That Diagram above is the starter circuit and we know it is already working.
If I remember correctly power is supplied during starting from the starter circuit but once released it is supplied by the alternator. So if your alternator is bad then it will not run.
Off the top of my head I believe there is a diode in that line to stop it back feeding the alternator during starting. I don't have the access to the circuit diagram just now.

 

[TuffleHunden]

Re: Starts and dies problem

Good Morning Dypcdiver, Thanks for the information! I had that thought but all that I spoke to told me it had nothing to do with the engine starting and running. I will have the alternator tested while continuing to check other possible solutions. Thank you!

 

[TuffleHunden]

Re: Starts and dies problem

Hello everyone, I really want to thank all those that tried to help this idiot!!!!!LOL I thought I would let you know that I have found the problem and after 10 minutes I turned the switch and engine started right up Just as I said it was trying to do. For those that don't know there are four prongs on a kill switch. When I switched the old one out for the new one I matched the wires up before I removed one and then put it directly to the kill switch and then the other. Knew I had it right. Tonight checking for power through the purple wire I got no power crossing the switch. Just as a hunch I moved the wires to the other post and BAM had power through the switch, and said to myself; Self give it a shot. But I waited until I took a probe, and checked all power throughout the lines EVERYTHING was a go at this point. I turned the switch and the engine rotated about twice and fired right up and idled just fine. I hope that this may help others in checking out the engine dies when I let the key to the run position. I again want to thank IBOATS and all those that have tried to help this IDIOT!> We can close this thread!

 

[TuffleHunden]

Re: Starts and dies problem

The Saga continues. Well I got ready to hit the water. Hooked up with water hose started engine and ran great for about 2 minutes.. Then died. No spark, troubleshot the problem to ignition module. Replaced ignition module and set gap to 8-10 as instructed. Got spark but engine will not start. Key was sporadic while turning to start. A few times I would turn the key to start and nothing and then other times it would turn engine over. The entire ignition line is new, switch, kill switch, starter, coil, relay, ignition module. Any ideas why it would not start after replacing ignition module?

 

[insttech1]

Re: Starts and dies problem

"Key was sporadic while turning to start. A few times I would turn the key to start and nothing and then other times it would turn engine over."

That is a classic sign that you have a bad wiring connection. Either loose, corroded, melted, etc....somewhere within the starting circuit.
Either that, or possibly a starter that is going bad.

I would check your main grounds to the block as well. Just because you can read voltage on a terminal somewhere does not necessarily mean that you have a good enough connection for the proper amount of current to travel thru that connection. Typically those types of connections will start to micro-arc, and start to show signs of heat damage, and/or melt the insulation back down the wire an inch or so.....

 

[TuffleHunden]

Re: Starts and dies problem

Hello insttech1, tonight I rechecked the switch and kill switch all seemed to be good, wiring looks good and in testing for spark at the distributor and plug the switch worked fine. However now I have no spark at all from the coil to the distributor. I do have in range voltage on the coil positive side but was curious about the negative side. It would jump from like 9 to the same voltage as the positive side which was like 12.75 in that range. I checked the wiring from ignition module, coil, to grounds, and to include the starter. This is really aggravating, especially when you think your just about there. I will check the grounds from the block but if I remember correctly in the beginning I did that and all looked fine. Could the neutral safety switch in the shift lever be causing any of this? Oh and by the way I do appreciate your help.

 

[insttech1]

Re: Starts and dies problem

This is hard to picture without the full wiring diagram in front of me.

But let's step back a little bit...and look at what's been done.
The boat sat for a while.
You've replaced most (if not all) of the components.
You've inspected most of the main connections involved.

However....here are some ideas:
Upon installing any new components, did you find any wiring connections w/ extremely white or green crud on them? That's corrosion.
Did you inspect the terminals that the new relay has been plugged into? Are they corroded or damaged on the back side?
You inspected the main wiring harness, but I assume from the front side. Were any of those pins corroded? Did you inspect the opposite side of that harness, and see if the connections to any of those pins are bad or the wiring is barely hanging there?

Can you post a link to your actual starting circuit?

Also, if you go back to your very original post, you say the engine died when you released the key to "run".
That makes me think that the relay is dropping out and not maintaining the "run" position.
Or, as others stated, the alternator may not be kicking in and taking over....but I'm not sure how that works with your engine, or if it would cause it do "nothing".

You can jumper--temporarily--the neutral safety switch to eliminate that as a problem.

I'm not completely sure what you mean by "negative" side of the coil....they don't really have positive and negative; they have two sets of windings, with the "negative" side that discharges to a resistive wire, or capacitor, or back to the ignition module. And a coil should be checked by resistance values when disconnected; not necessarily by voltage. But yours is new, so we should assume it's good, if it was replaced with the correct part.

If you see any corrosion on any of the connections, clean them w/ a wire brush, and use some dielectric compound if necessary when re-seating them to keep moisture out.

 

[TuffleHunden]

Re: Starts and dies problem

Well I will try to go one by one starting with I have found no corrosion on wires or connections as I replaced parts. I did replace the inline fuse at the ignition switch with new connector and fuse. I did inspect all terminals and unwrapped all wiring to trace lines and found all to be in good condition. the main wiring harness it was disconnected and inspected for loose pins, wires and from both sides. I tried to up load a wiring diagram for the ignition system but could not figure it out, it allowed me to upload but could not figure how to drop and drag to area needed. The diagram came from the repair manual and is pretty detailed and that is what I followed as to tracking lines to and from each particular part for testing. The original post of not running when the key was released was found to be the kill switch and once replaced it fired right up. It ran for about 2 minutes and died. Now we are at this problem of no spark and no attempting to start. I only referred to the pos and neg side of the coil as to this is the way it was marked on the coil. I will check the engine grounds out this evening for corrosion and connection. Thanks

 

[TuffleHunden]

Re: Starts and dies problem

I checked the grounds out tonight and they seem to be in good shape. No blue, White, gray, or anything that looks like powder around either end. I even checked for continuity just to be safe. I also checked the Ignition line out again tonight. Power seems to be where it should and going to where it should. I just do not have a spark either from the coil or plugs. Your thoughts.

 

[jackd1023]

Re: Starts and dies problem

I would follow the PURPLE WIRE,

 

[insttech1]

Re: Starts and dies problem

I think the best thing you can do right now is figure out how to get that circuit diagram posted on here so we can all see it.
The link to the merc' one that is in the post above is not that helpful, and doesn't show your exact diagram.

Also, I would closely inspect the main positive and negative battery cables on your batteries. Are the huge lugs and the wiring
directly attached to them clean and copper looking, or are they black/grey/nasty looking? And how about those same connections to the switch that you said you installed between the two new batteries?

Also, when you say you are checking the connections, are you wiggling the wires at every crimp on terminal? They can become
brittle after time due to vibration. Just a few weeks ago I had one snap off the back of my alternator right where the wire enters the crimp for the lug terminal.

 

[TuffleHunden]

Re: Starts and dies problem

View attachment volvo penta 5.0 FL PHUE wiring0001.pdfhttp://forums.iboats.com/ Ok I think I got the diagram uploaded. It was to large so had to reduce it. Also the battery cables and batteries are brand new. as to the wiring yes I have pulled tugged and wiggled nothing seems to be loose, broken, brittle etc. I have complete power to the coil. Just nothing coming out of it to the distributor in order to get a spark.