502 not starting
 

I was running 3600 rpm's for 45 min and engine just died. Like I shut off the key and won't restart. It didn't get hot, oil press was ok. I put over 15 plus gallons of new gas on top of a 3/4 tank just to be safe. I was able to get jump packs on both batteries , no start. The batteries are brand new. Any idea. I think it is electrical. Not fuel, or battery related. ?????

Engine cranks over fine. I got it to run today for about a minute. Died, just as it did yesterday. Not sure if I have an MSD (Ignition)? checked all "kill" switches, Breaker not tripped. Where is the fuel separator?

The first thing I would do is pull the water sep fuel filter and dump the liquid into a clear glass. Let it sit for 20-30 mins. Water will settle on the bottom.

If you are going to be diagnosing and repairing yourself you need to start with the basics.

Get a inline sealed spark tester and fuel psi tester. These should always be performed first and then computer scanned for codes.

Something like this should be fine for checking fuel psi. Not enough people have these. There are different fuel psi values for these motors depending on year and engine serial #. So ask here for values when you go to check.

This type spark tester - most all parts stores have them. Everyone should have on in there tool box. Only $10-$15.
Look online to get visual idea (if there is spark) on what is weak (dim spark) vs strong (bright)spark.
Lisle 20610 Inline Spark Tester
by Lisle
Link: http://a.co/93Ha5YY

https://cimg1.ibsrv.net/gimg/www.off...117c009676.jpg

Distributor module

It's funny you say Distributor Module. I had a Z-28 with a 350 in it. When it would get hot it would just shut down. it ended up being the (brake pad shaped) module in the distributor. Popped it out, put in the new all was fine. I could not idle the car enough to replicate the problem. Probably needed a load long enough to create issue. I thought of that as soon as it happened. I didn't think there was a module in my distributor. I started the engine today and it ran for 10-15 min. like no problem ever. Now I can't trust it to go out on it. I'm going to have a local mech.look at it. At least he will have all the computers/code readers needed. Thanks guys

The module is more common in the cars vs boats, but still have some go bad in the boats.

I repaired a boat yesterday that after 5 minutes on plane would sputter and then die. After an hr or so would restart like it had no issues.

Grabbed my $15 ignition tester as above and went for a quick ride. It died, it had no spark.

I have spare good modules (EST and Tbolt IV) and coils for the different systems .

Replaced the module as this is way more common than the coils and condition was still there. Replaced the coil and all good. BTW: I did quick check on coil first and it was not hot nor any oil leak.

I took the module back of course. Charged him for coil and my time. Not the sunburn. LOL.

BTW: If you ever change the module make sure to use real heat transfer compound like Arctic Silver or the like. Most of the 'compound' that comes with modules is clear which means it is dielectric grease which does not transfer heat. Heat is #1 module killer. Use compound sparingly, and use razor to leave very thin film. Leaving thick is inefficient for transferring heat.

That $15 spark tester is one of the best tools out there. Amingly one of the cheapest too.

[QUOTE=SB;4631475]The module is more common in the cars vs boats, but still have some go bad in the boats.

Between my brother and a friend they went through 5 in 2 seasons in their boats, could be the Chinese factor.

I replace with ACDelco (if the EST) and mark my words on the heat transfer compound and read up on how to clean and apply.

All aftermarket companies modules are as reliable as the 86 Hyundai Excel.

Also, 99.9% of any module (OE and aftermarket)comes with got damn dielectric grease , even though it says heat transfer compound. I've been *****ing about this for almost 30 years when all the companies went dumb with this. This includes GM. Ford, and Chrysler.

Clear = dielectric. No good !

Get and use Arctic Silver or whatever your local computer company uses for ECU heat sinks.

one needs to differentiate is the issue fuel side or ignition or sensor side. If one is going to work and attempt to fix their apps properly - good tools are needed and all the proper service manuals. .

Odds would say to me without the testing factor the issue is NUMBER 8 in the link below. Buy the Merc one not sierra..

. MerCruiser 502 Mag. MPI Bravo (Gen. VI) GM 502 V-8 Distributor & Ignition Components Parts

Just an FYI its called the pick up coil. in the link above - Not a module

You've run into more issues with the magnetic pick up vs the electronic module in the EST distributor? Interesting. I have totally different experiences. We are on fresh water if that matters.

17 year old to 25 year old electrical ignition component not going last forever. even spending its whole life boating in Lake water.. EST no start 1 st place Im testing is spark and fuel pressure ----- if no spark --- moving on with testing coil and the pick up coil. Odds are pick up coil for the ignition side. Cap and rotor SLIGHTLY in the mix depending on weather / humidity / corrosion and age. Most of the time engine will start but run poorly with bad cap / rotor.

It happened again. Same issue as before. Could bad gas present it self 1/2 to 3/4 of an hour into a ride? I've taken several rides before this for an hour or so and no issue. When we scanned the motor before, we found nothing out of the ordinary. I'm not a mechanic, so my investigation may not be up to parr. I'm thinking on getting rid of the fuel, but was told how expensive it is to dispose of it. So I would like to know before I do it.

It doesn't sound like the initial cause was ever found??
What was done to it after your last post on June 11???

We found a loose wire on the starter. With it hooked up to the computer, we couldn't find anything else. If it is bad fuel, could it be that intermittent?

If the water sep fuel filter had been changed, I would say yes, since it could have filled with water again.
Since it was not changed, then I'd say no. Something in the ignition is probably going bad and displays the problem when it gets hot.
I'd lean toward the dist pickup module going bad or possibly coil.

OP had the exact same issue with a brand new '99 5.7L EFI and it was ignition module. Boat would run like a champ for 20 - 30 minutes then boom, dead. You could let it cool off for 30 minutes then it would fire up and run fine again for another 5 minutes or so then die again. Boat only had about 10 hours on it when it did it so they can be bad regardless of age/hours.

Hey SB -- the est for the 454 and 502 --- I was not comparing failure rates between the pick up coil vs the ignition sensor assembly. Keep in mind the 502 and 454 OEM stock used the est ign set up inwhich used the pick up coil internally.