1996 5.7LX Crank no start only one spark?

[subysti]

OK I thought I checked everything but tonight when checking for spark I noticed in the dark that I only get one spark when cranking. Would that be the coil? Or is something telling it not to spark anymore?

 

[HT32BSX115]

Re: 1996 5.7LX Crank no start only one spark?

OK I thought I checked everything but tonight when checking for spark I noticed in the dark that I only get one spark when cranking. Would that be the coil? Or is something telling it not to spark anymore?

Hmm. You have Witches in MASS don't you?

JUST KIDDING!


If you only have one spark plug sparking (and I'm assuming you pulled them all and grounded each and cranked it?)

You should probably consider a new dist cap, rotor, plugs and spark plug wires.

I think you have either Thunderbolt IV or V. If it's sparking on 1 it should be sparking on all of them. (and it will be a HOT spark too!)


Cheers,


Rick

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

Lots of witches. I think there's one upstairs sleeping! As for the spark, I just checked one. Figured it would be the same on the others. It's a thunderbolt V. I checked one other and seemed to get a dim orange spark so I'm thinking it's the coil.

 

[HT32BSX115]

Re: 1996 5.7LX Crank no start only one spark?

Lots of witches. I think there's one upstairs sleeping! As for the spark, I just checked one. Figured it would be the same on the others. It's a thunderbolt V. I checked one other and seemed to get a dim orange spark so I'm thinking it's the coil.

SHHHHHHHHH BE VEWY VEWY QUIET!!!




Well, you have one of the best (if not THE best) ignition systems ever put on a boat!

It's possible that you have a bad coil, but I would do the other "stuff" too....you also have a module that can be a problem but I'm thinking that they either work or they don't.

I also have the T-5 on my 454.

 

[achris]

Re: 1996 5.7LX Crank no start only one spark?

It's the same coil firing for all cylinders, so if you have one (or more) good sparks, and one (or more) not so good, then it's either the cap, rotor or the spark plugs leads.

What exactly do you mean by ....

when checking for spark I noticed in the dark that I only get one spark when cranking

Is that one spark per revolution, or just one spark total? Or something different?

Chris.......

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

Just one spark. When I crank the engine I get one spark initially then no more.

 

[Don S]

Re: 1996 5.7LX Crank no start only one spark?

Remove the distributor cap and see if the rotor is turning when you crank the engine.

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

Ok distributor is turning. I did get another coil but haven't tried it yet. It's a generic napa coil but it says use with external resistor. What's that mean? I figured I'd try this just for diagnosis before buying the pricey mercruiser one.

 

[Don S]

Re: 1996 5.7LX Crank no start only one spark?

Before you start throwing parts at it, might want to follow this chart. Is the high tension lead from coil to distributor corroded on the ends, the cap? Rotor?

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

Well went through the crow chart and got the the point of checking coil on step 5. It says to replace ignition sensor. Hope that's right. No one around here has one in stock because they say it's a rare item to break on these ignitions. Is there a way of testing the sensor besides what's on this chart?

 

[dingdongs]

Re: 1996 5.7LX Crank no start only one spark?

ere ya go;http://www.ebay.co.uk/itm/MERCRUISE...rts_Accessories_Gear&hash=item2eb5ee89c7#shId

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

Wow. I can't freakin believe it. After screwing with all this I found the problem. I went out to pick up my tools and cover the boat as there was a storm coming. Just for the heck of it I checked the shift lock out again. This time with a meter. With it and neutral and forward gear it was open. I put it in reverse and it closed, huh? I tried starting it in reverse and it fired up right away at 4000 rpms!! Pushed it back in to neutral and it quit. Long and short of it was the switch was sticking. Took it out cleaned it and all is well again........ Now if it would stop raining.

 

[Don S]

Re: 1996 5.7LX Crank no start only one spark?

That is the neutral safety switch that controls the starter. It has nothing to do with spark, and spark is what you were asking about. I'm confused. :facepalm:

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

I don't know then. Maybe there was a loose connection somewhere I reseated when checking. I know it still wouldn't start unless I put it in reverse.

 

[Don S]

Re: 1996 5.7LX Crank no start only one spark?

Can you crank the engine over in any position? If you have it in fwd, neutral, or reverse, can you engage the starter and make the engine turn. (Not start, just turn over).

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

I'm not sure what I fixed. I know that before it started to work again it would not crank it forward gear. Just clicked. It still wouldn't start until I put it reverse then it started. I'm not sure if it was actually in gear though.

 

[kennycarter]

Re: 1996 5.7LX Crank no start only one spark?

Would your flow chart be the same for a thunderbolt IV? My problem is the same as described above, only one weak spark. The motor is a 5.7 4v in a 1995, alpha one, I think it is a thunderbolt IV, but it has an additional sensor besides the ignition module mounted on the distributor. I thought I read in this forum that makes it a thunderbolt V? I Would like to try to narrow down the problem & not throw parts at it.

 

[Don S]

Re: 1996 5.7LX Crank no start only one spark?

No, and you really need to start your own thread when you have a problem, not hijack someone elses thread with your problem.

 

[achris]

Re: 1996 5.7LX Crank no start only one spark?

Start your own thread, and post your engine serial number, and photos...

Thunderbolt IV and V have very different troubleshooting and set up procedures..

Chris......

 

[subysti]

Re: 1996 5.7LX Crank no start only one spark?

I don't mind him hijacking my thread. I'm not sure what fixed mine but it wasn't the flow chart. There had to be a loose wire or something. I know I fiddled with the shift position switch and when I put it in reverse it started. Weird. I know the switch works because if it's in gear it won't turn over at all and I checked it with my Dvm. Once it started it ran rough more searching I found I had 3 plug wires wrong. It ran but no power and very hard to start.