low hour 8.1 engine stalled and keeps stalling

D

DaltonGang

Member
Aug 11, 2020
104
Boat Info
1995 SeaRay 370 Sundancer
Engines
8.1 Horizons
My engine has just 270 hours. Salt water boat & installed in 2016.
I was going about 6 mph for 30 minutes and one engine just died. It would crank but not start.
After I got into the slip I tried again and it did start for 30 seconds or so and then died. The longer I let it sit, it seemed like it would run longer.

I hooked up a gauge to the fuel rail and turned key on, got around 40psi (normal)
started it and this video is what happened


To me it looks like it runs out of fuel. I tested the fuel pumps in the module and both ran at 12v.
Filter was fine. Plenty of gas in tank, lines are all only 6 months old.

But maybe its just losing power so the fuel pressure drops??

at one point i ran the engine at 2000 rpm in the slip for a minute and it died. Then I start again and it idles for 20 seconds and dies.
So again, the longer it sits the longer it will run it seems.

I have spare fuel pumps, regulator and filter so I am swapping them out in the fuel cooler (gen 3 no paint flake issues).
My mechanic said it seems electrical. Try TPS or the main cord going to engine. Wiggle stuff and see.
He said gas tank vent could be clogged too.

I guess I had it in my head it was fuel related because it just makes the most sense watching it drop and no errors.

Edit: I hooked up a rinda scanner and it showed no error codes. After starting it and trying for hours it did finally show 2 codes. Crank position and cam fault. But I think its just because it was stalling out or not starting sometimes.
 
8.1's had problems with the crank sensors. Careful not to break it off when removing it.
 
And, make sure you've got good 12v to the engine. I had a bad alternator, and when the battery finally started losing voltage, I got all kinds of weirdness. ECMs hate low voltage and bad grounds.
 
What about water in the fuel?
 
I did switch out IAC and nothing changed. I tried removing the crank position sensor but its really in there! I need a different tool to pry it out. I'm going to try a door panel removal tool which is the right bend on it. I have the sensor on order. I've ordered a few possible cheaper parts as I don't want to keep trying just 1-2 things each time I goto the boat. I'd rather just make a day of it and switch out all possible issues. (I know it costs more doing this but I'm ok with that).

I have a list of things I will try now. I wasn't sure what to start with but now have a pretty good idea.
An easy test is just use the valves and run engine on opposite tank which could rule out a few things.
 
Ugh, one of the challenges with a boat being far from home and trying to diagnose and fix something, I hate that.
 
DaltonGang said:
I did switch out IAC and nothing changed. I tried removing the crank position sensor but its really in there! I need a different tool to pry it out. I'm going to try a door panel removal tool which is the right bend on it. I have the sensor on order. I've ordered a few possible cheaper parts as I don't want to keep trying just 1-2 things each time I goto the boat. I'd rather just make a day of it and switch out all possible issues. (I know it costs more doing this but I'm ok with that).

I have a list of things I will try now. I wasn't sure what to start with but now have a pretty good idea.
An easy test is just use the valves and run engine on opposite tank which could rule out a few things.
Click to expand...
As posted above. Find the root cause of your fuel pressure drop off. Measure the voltage at the fuel pump when the pressure drops off. Closely inspect the fuel pump relay and it's connector.
 
I have a similar issue. I was out this weekend cruising around 25knts and started to throttle down and my starboard engine died. It just stopped, no sputtering. It cranks fine, has fuel pressure in the rails but doesn’t have spark. It didn’t throw any error messages on the system monitor either.
I’m going up tomorrow to check for 12v at the coil packs and am going to take a guess at the crank sensor and try to test it. Does anyone have a pic or video of where the crank sensor is?

Anyone have other ideas?

Thanks,
Ray
 
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To Ray (post #10)

Yours sounds like a crank shaft sensor failure. When it fails it does not throw a code and the engine will not have spark. The sensor is located on the bow side of the engine and slides down into the block, only a connector and bolt is exposed. See # 7 block picture.

Part Number 892617

Easy test - swap the one from your operating engine over to the non-operating engine.

A couple of us running 8.1s keep a spare on our boats. No warning signs - the sensor just fails, and the engine won’t operate.
 
When I read the previous post, I was going to tag you, then I saw you already replied! Ty
Mig22 said:
View attachment 149292 View attachment 149291 View attachment 149290 To Ray

Yours sounds a crank shaft sensor failure. When it fails it does not throw a code and the engine will not have spark. The sensor is located on the bow side of the engine and slides down into the block, only a connector and bolt is exposed. See # 7 block picture.

Part Number 892617

A couple of us running 8.1s keep a spare on our boats. No warning signs - the sensor just fails, and the engine won’t operate.
Click to expand...
 
So I came up to the boat and was ready to pull out the crank sensor but tried to start it to make sure I still have the same issue. Guess what, it started and sounded fine.
I let it run with the hatch open and revved it a few times, all good. I closed the hatch and left it idling and a few minutes later it stopped and will not start again. The engine temp is about 140 per the water gauge. My infra gauge on the outside of the engine says it's about 103

Could this still be a crank sensor problem or does anyone have any other ideas?
 
Could be the sensor. If it develops a crack inside it can operate nominally while cool, but once it heats up and expands, the crack becomes wider and breaks the electrical contact.
 
It's about. Anything is possible. When I got mine the bilge pump would turn on with the helm switch. But not with the float, went thought what I thought was everything and replaced the float switch. Only to find out the five amp fuse was bad in the engine bay
 
I replaced the Crank Sensor today and let the boat run for an hour. Engine was at full temprature and the hatch was closed.
I did put in a crank sensor from a 2002 Chevy Surburbon 8.1 and it was 74.99

Thanks for everyone's help!
For future reference to my fellow boaters. This part took a whole 10 minutes to change. One bolt and the sensor pulls right out.
 
Awesome. Glad you are fixed
 
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