1994 5.7 liter won't start

[jay jasper]

1994 2452 with 5.7 liter, 4 barrel with Bravo 2 outdrive. Engine serial number 0f274795
As far as I know, it's a Thunderbolt 4 with the "intensifier", or what ever it's called, on the distributor not the exhaust manifold.
In a nut shell: I had a cooling hose blow out. I turned the motor off, attempted a repair and started it again. The repair failed and I turned the motor off and got a tow. It was salt water.
The motor never killed on its on.
The boat sat for a couple of weeks waiting on a complete hose update.
The motor will now turn over, but will not start. There is nor sign of salt water intrusion in any of the connections, including the main harness plug.
Brand new plugs. I do get a spark at the plugs, which are the exact plugs the manual calls for. AC Deloco MR43T, gapped at .035 The spark is blue and orange.I would like to see blue...
I get 12v at the coil and it doesn't drop below 10v when cranking. I have run a direct line from the coil to the battery which did no good, as changing the coil did no good.
I tried starting with the tachometer disconnected.
I am getting the correct voltage to the sensing unit, which is brand new since this issue.
One difference is that the new unit has a ground, whereas the old did not. I have tried it with the ground grounded and with it not grounded.
The rotor and distributor cap looks good.
The plug wires are less than a year old.
I have even tried starting fluid. I'm losing my mind! Who's thought an old small block Chevy could get complicated!
Awesome site, hope someone can help.

 

[alldodge]

Howdy
Are you getting constant spark as it looking from the coil wire?
Is the carb flooding?
Pull some plugs to see if they are wet

 

[jay jasper]

Getting fuel to manifold. Not flooding.
Verified spark.
Verified plug wires on correctly/proper order according to the numbers on the distributor cap, which only goes on one way.
At TDC the rotor points at #1 although the post labeled #1 on the cap is 180 degree off from #1 plug.
I moved the wires where number 1 wire was on post post "pointing" to number one plug to try it and got a backfire through the carb, so I put them back like they were.
The motor doesn't "kick" when primed. The only sign of life was the backfire through the carb when the plug wires were on wrong.

 

[alldodge]

Getting fuel to manifold

Your serial number is coming up as a carb, not understanding the term "manifold" with reference?

I'm seeing TBV ignition. I know you said there is good spark but have you tied the TBV trouble shooting guide

 

[jay jasper]

When I typed "manifold" I mean that I am getting fuel to the motor, not just to the carb.
I did the troubleshooting guide and it led me to replace the ignition sensor.
I have to be missing something small...or something is flakey but not yet totally broken.

 

[alldodge]

You did the TS guide and it said to replace sensor

In order for that to happen then spark is not happeneing

Remove the distributor cap and crank the motor to see if the rotor is turning

 

[Bt Doctur]

At TDC the rotor points at #1 although the post labeled #1 on the cap is 180 degree off from #1 plug. there is a TDC on intake and TDC on compression so it wiil happen twice The motor was running to timing and plug order was correct. Locate #1 position on the cap ,order is 1,8,4,3,6,5,7,2 clockwise . Facing the motor on your right is 1,3,5,7 on your lest is 2,4,6,8

 

[jay jasper]

My #1 points 180 degrees from number one plug from the factory.
The rotor is rotating.
I replaced cap/sensor in cap/coil/plugs. I'm getting spark to the plugs and getting fuel to the motor.
I troubleshot the started today since it seemed like it may be turning over a bit slow.
But, of course, the more you run around in circles, the more you see real and imagined issues.
Although these numbers aren't perfect, they aren't bad enough for me to pull the starter...unless the internet has a consensus that it needs to be done.
The terminals all appear to be clean/corrosion free.
Battery voltage: 13.5
Hot Circuit
B terminal on solenoid to Positive battery should = 0 volts
-Not cranking = 36 millivolts
-Cranking = 1 volt
Ground Circuit
Negative on battery to starter housing 0 Ohms / 21millivolts
-Cranking = 0.7 volts
S terminal to positive on battery should be battery voltage (circuit open)
-Not cranking = 13.48 volts
- Cranking = 1.6 volts
1.6 v difference S and pos
I'm fixing to bite the bullet and take it to a shop...I hate it, but I'm stuck

 

[alldodge]

I'm getting spark to the plugs and getting fuel to the motor.

If all plugs are firing, and fuel is making it to the plugs then it should fire, or back fire.

If you can give it a shot of either and it still does not fire, then the fire is not making it to the plugs

 

[jay jasper]

If all plugs are firing, and fuel is making it to the plugs then it should fire, or back fire.

If you can give it a shot of either and it still does not fire, then the fire is not making it to the plugs

I am getting fire. I've checked it at the plugs. That's the kicker.

 

[jay jasper]

So, I finally gave up and brought it to the shop.
Major defeat but I can only do the same things for just so many times...
They had found that I had no compression on number one.
Since everybody had to come get their boats because of the hurricane anyway, I'm doing the rest of the troubleshooting and repair myself.
I guess I should have checked it my self when starting fluid didn't work, but I did check my oil and it looked good.
My guess is stuck valves. I'll pop of the valve covers when the weather gets better.
I can't say enough about Templet Marine in French Settlement (Louisiana). Fast and more than fair.
I'll update thread when I know more.

 

[jay jasper]

Looked at motor today. Bore scoped the cylinders. I have valves with corrosion on them.
Water got to carb, although it was running fine when I turned it off...
Took off valve covers and bore scoped the cylinders with loose rockers.
The valves that were open when I turned it off are prevented from closing due to corrosion.
They do open more when the lobe comes around, but do not close completely.
Thinking about putting plugs in and "misting" the intake with some sort of lube and see if I cant get them to close. I'd try some cord in the cylinders but I'm afraid it's get tangled in the open valve before pushing it closed.
I am in denial, the motor will come out, but if there's a chance it doesn't have to , I'll try it.

 

[alldodge]

Pull the head and inspect to see if a valve job will fix the issues. If it will then your just out some gasket and valve job.