Stalls, restarts, stalls, wait...runs for a bit.

[dennisbuter]

Could anyone point me to what may cause my 97 challenger 787 to stall out after about an hour of running?
We were cruising around for about an hour, running about 6krpm when the engine quit. It restarted right away, but stalled 5 seconds later, and would continue to restart then stall quickly. We paddled ashore, checked plugs, wires, fuel filter, opened the electrical box, no obvious problems. After about a half hour, we started it up and it ran fine for about 15 minutes, then quit, would restart, then stall. It seemed to be fighting to idle, then would quit. I recently changed the plug wires from the coil to plugs, but thats about all that I have messed with.
Has this happened to others? I searched the forum quickly but didn't find anything.

Thanks,

Forgot to mention...we did a compression check, 150 psi on both (recently rebuilt)

 

[seadoosnipe]

DESS post.....

Your DESS post is bad. I had the same problem on my Challenger last season. I replaced it and haven't had the problem since.

Because the post is magnetic, I think it looses it's ability to communicate with the ROM (read only memory) chip in the lanyard cap........explains the reason why it will restart and stop.......vibrations...etc...

I have a post in my thread, "a look inside the 787" which has this post out of the boat. Click on the link at the bottom of my post.
You can change this yourself. The part is in our warehouse under "electrical accessories" and is part #18. It'll cost about $87 bucks. Keep this in mind if you decide to get it quicker by going to your local parts distributer. In some of the shops, their mark up is outrageous.......which is why I shop here!........

 

[timmyboy76]

also, did you mess w/ the fuel selector at all?, try in "res", see if better..

 

[dennisbuter]

Thanks for the pointers guys,
I didn't try the "reserve" fuel selection, but should have...
It seemed to be robbed of fuel, or seizing...it would start, then fight to stay running, and slow to a stall from idle, or just stall out fast if running at anything much above idle. After a compression check, we ruled out seizing.
We noticed that the magneto connector wasn't fully seated, so removed cleaned and replaced it. We then put a bottle of fuel line anti freeze into it, to emulsify any suspended water in the fuel...just to rule out water in the fuel. I took it out today with a rescue boat close at hand, and it ran fine for over two hours. Tried messing with the DESS while running to see it that had an effect, but it didn't.
Now I'm concerned...what was the issue, and when will it return???
Could the DESS cause the engine to bog down, then stall? Or would it just shut the engine off hard? Could the magneto connection cause it to bog down and stall, or would it just stop hard as well?

Any info, and all suggestions are welcome and appreciated!

 

[timmyboy76]

if it was mak'n bad connection, then it would act up and give wrong spark time/ no spark at high rpm, caus'n symptom like static throughout the electric...."if it returns..urrrrrgh", try the selector switch, if noth'n, then unpplug red wire from rectifier, then give her try again..:cheers:

 

[ontariospeedster]

Clean your gall darn carb-a-taters....

got fire insurance?

 

[dennisbuter]

We went out for the day, and after about an hour of running, same thing again, engine quit...
So, I turned the fuel selector to "reserve" and started it up again, it ran for about 1-2 minutes, then quit again...
Messed around with the DESS, started it again, and it ran fine for about another half hour, then quit.
Popped the hood, checked the stator connector, and was going to remove the "red" wire, but only found two yellow/green, and two red/blacks, so didn't disconnect it.
Started it up again, it ran for 5 minutes, then quit, restarted, and noticed that it wasn't revving up as high as it should...
Then, as we were coming ashore, it was idling really rough, and wouldn't start as easily as before...
Could a failing coil cause this?
Does anyone know how to jumper out the DESS for testing?

It has mis-fired in the 4-5k rpm range since its rebuild, and we noticed one of the rave valve bellows was ripped...this needs to be fixed for sure, but would/could it contribute the stalling/rough idle issue?

Again, thanks for your input guys...

 

[dennisbuter]

Forgot to mention...I have not had my carbs cleaned yet.
I'm sure it will only help having them cleaned..and it may help witht the 4-5k rpm sputter...

 

[Turbo442]

exhaust leak into engine compartment. Try running with engine hatch open when it occurs.

 

[Nate Surveyor]

replace gray fuel lines yet? doo a search on fuel lines.

if not, you will have too

clean filters, cleanout carbs.

N