OMC 460 won't start

[BlowHo]

I have posted this before, got some advice, tried numerous things, read as many posts as possible and the end result is I'm confused.

Details:
Engine is a 460 King Cobra, Model #754APEPW5-(5 maybe S?) SN T01205263.

Boat sat for over a year, I changed all fluids. I got a good deal, but bought from a friend of the owner who had moved out of state. Supposedly, the engine has less than 60 hours on rebuild. Lots of corrosion, boat was operated in Salt. I have cleaned a ton of it off.

Motor cranks slow but will not start. Batteries were load tested and they are good. I have replaced the starter and cleaned every electrical connection related to ignition. I have replaced the plugs, wires appear to be OK, it has the Spitfire ignition system. I have purchased a factory manual.

My problem - I do not have a compression tester, however when I pulled plugs the boat cranks faster than when they are in. Low tech, but is it logical to assume I have SOME compression based on this?

The carb is an Edelbrock and appears to be OK. It is getting fuel. Occasionally it backfires and I tried starter fluid once (You guys told me to stop that crap) and I did have a flame ball shoot out of the carb. So, it must be getting spark?

I have pulled plugs while cranking and do not have water coming out. Manifolds and risers are in really good condition.

The attached picture is the back of the intake manifold, I am not sure what these two items are, or if they would be causing any issues, they obviously are corroded and need replaced. The question is what are they and would they be giving me the problem?

If the wires are shot, would that cause the problem?

I have always repaired my own cars, (nothing major) I am not afraid to get my hands dirty. I suck with electrical, I do have a multimeter but it might as well be the space shuttle. If I have specific instructions I am smart enough to figure out how to make it work.

Anybody have any advice for me to get this thing going? Sorry for the long post, but I am frustrated. If nothing else, is there a recommendation for a good marine mechanic in the Tacoma, WA. area?

Outdrive says King Cobra, has the hump and the impeller is right on the back. Model # 98604, SN T0725770

Is this the cone clutch or dog clutch style.

Thanks for any help.

 

[Bondo]

Re: OMC 460 won't start

The Picture is of an Oil Pressure Sending Unit(the Big 1),+ an Oil Pressure switch(the Small 1).........
If you have an Electric Fuel Pump,....??......
It's Probably Supposed to be wired thru that Switch,.......

and I did have a flame ball shoot out of the carb. So, it must be getting spark?

That tells Me that it's getting Fire,.......
But at the Wrong Time,......
Are you SURE that the Plug Wires are in the Right Order,..??....

Outdrive says King Cobra,

Sorry to hear That,................

 

[Coors]

Re: OMC 460 won't start

That looks like the oil sender, with an oil switch If the switch is bad, or not a good connection, if you have an electric fuel pump, it could cause the pump not to run after you let go of the key.

 

[BlowHo]

Re: OMC 460 won't start

It is mecahnical fuel pump.

Bond-O - You might be the man, I checked wiring order, 4 of 8 were wrong according to the service manual! I'm gonna get it out of the garage and give it a go. It sits sideways in a three car bay so it is kind of a chore.

While I am doing that...

My attempts to start have gone like this:

Turn power on to both batteries
Pump it twice in neutral and leave it at 1/4
Try to start.

My question is does it have to be locked in the upright positio to start, or does it just have to be in neutral?




Anybody know what outdrive I have, cone or dog??

 

[Coors]

Re: OMC 460 won't start

bondo types faster

Don't know your controls, but usually there is a throttle only button, or pull the handle out 1/4".

 

[HT32BSX115]

Re: OMC 460 won't start

Bill,

If it has the "hump" it is my understanding that it IS a cone clutch.

That's a good thing. I didn't even think of the firing order. If someone has messed with the wiring they could be way off! You absolutely need to check each plug wire.

By the way, I have a good used fuel pump you can have if you need it. That raw water impeller is still here if you need it too.

By the way I AM handy with a multi meter and I do have a compression gage.....Let me know if you want to give it a try.



cya/Rick

It is mecahnical fuel pump.

Bond-O - You might be the man, I checked wiring order, 4 of 8 were wrong according to the service manual! I'm gonna get it out of the garage and give it a go. It sits sideways in a three car bay so it is kind of a chore.

While I am doing that...

My attempts to start have gone like this:

Turn power on to both batteries
Pump it twice in neutral and leave it at 1/4
Try to start.

My question is does it have to be locked in the upright positio to start, or does it just have to be in neutral?




Anybody know what outdrive I have, cone or dog??

 

[BlowHo]

Re: OMC 460 won't start

Rick - thanks for the offer, I might have to take you up on it. I hate bothering people with my problems, time is valuable to everyone.

OK, it's not backfiring anymore, but it's still not starting. After several cranks, the carb sparyed fuel up in the air about 3 feet. Not a steady steam, just a squirt. It did this twice. I have the flame arrestor off, does it have to be in place for the engine to start?

Could the old spark plug wires be fried from being in the wrong position. During my reading about boats I thought I remembered reading that boat wires are different than car, something about them being fragile.

Any help is appreciated.

 

[Coors]

Re: OMC 460 won't start

Timing, or valve timing(cam jumped timing)

 

[HT32BSX115]

Re: OMC 460 won't start

Yes that could be possible....This engine was supposedly rebuild recently. (yeah it could happen on a "rebuilt" engine)

One would think that the timing set WAS replaced.....they are fairly cheep!


Bill,

It will run with the flame arrester removed....you absolutely want to have a fire extinguisher handy though!

Pull the dist cap off and the #1 plug.

find TDC for the number one and ensure that you have the plug wires matching the firing order... it will run with 2 wires reversed.

Nothing should shoot out of the carb though unless it backfires. that would happen if it's flooding and a sparkplug fires/ignites with it's respective intake valve still open. I think you still have a timing and/or sparkplug wire problem. Is the dist cap in good condx? if there's arc over inside the cap it could cause backfire etc. Do you have a timing light?

If you have old/burnt sparkplug wiring they could be arcing over to each other too. having them on the wrong plugs shouldn't hurt them at all though...

Timing, or valve timing(cam jumped timing)

 

[Coors]

Re: OMC 460 won't start

Yeah when I ever saw raw gas shoot out of a carb, the timing cover got taken off.
Pull #1 plug(pull all to make it easier), hand turn the engine with a straw or something in #1.
when #1 is at the top, look at the timing mark, it should be real close to correct.
To keep from pulling the valve covers, turn it until the piston comes up again, it may have been on exhaust stroke. And check timing mark.
If the timing is close, and the wires are in order...sounds like chain
Try this; what was compression when it ran, and what is it now?

 

[BlowHo]

Re: OMC 460 won't start

No distributor to pull, it is the electronic ignition with individual coil packs. The manual has a test which I will do, but my multimeter batteries are dead so my wife is getting me some.

The manual says timing is controlled electronically as well. I don't know compression numbers when it ran, it hasn't run since I got it. I don't have a compression tester, so I don't know numbers now.

I really did get a great deal on this boat and factored in potentially having to replace motor. However, I don't think I need to, this thing has something minor wrong that if I identify I know it will run.

I would like to get a summer out of it and then spend the winter doing what Rick has done.

Anybody know anything about the Spitfire electronic ignition systems??

 

[Coors]

Re: OMC 460 won't start

If it is the timing chain, it is easy, if you don't have to raise the engine to replace the timing cover, I don't know if the cover involves pan removal.
To check before taking it apart, you need to know where the valves are when the piston is at TDC, which involves a piston stop, and dial indicator on the rockers.

 

[HT32BSX115]

Re: OMC 460 won't start

Alrighty then!


No dist!


This means that it's probably got a crank sensor to tell the system crank position. This is where the correct service manual will come in handy....I think you said you have one.


The service manual should have a test procedure for that system.

I have never fooled with one of those, But I can follow a service manual procedure as well as anyone....

My offer to help still stands. I can also bring the compression gage. But I'll bet you have adequate compression. This problem is probably entirely in the electronic ignition system.


The service manual test procedure will probably indicate if you need to replace something.

 

[BIGLICKER]

Re: OMC 460 won't start

I'm not too sure the timing is wrong, if its not been run for a while things can get stuck! As in a valve open which would also cause your engine to spit back through the carb! If I were you I would remove the rocker covers to see whats happening when the engine is cranked, watch each set of rockers to see if the valves are closing, also use a set of feeler guages on them to make sure they are opening and closing correctly.
A friend of mine recently came to mine on his "rebuilt" trike, and said its slugish although it was running. I listened to his engine and could here a popping noise from his right bank of cylinders. I checked the tappits and one piston had no gap on inlet or exhaust, I adjusted them and now its running like a dream.
Just a couple of possibilities for you that are easy to spot, without a multimeter.
Good-Luck, Roy.

 

[Coors]

Re: OMC 460 won't start

Good ,HT, I don't know crank sensors; that might be affecting the timing.

 

[BlowHo]

Re: OMC 460 won't start

There is a test for the crank sensor, however the manual says I need the special OMC tool for checking it.

I was able to follow the directions to test the coil packs with multimeter, 2 banks failed, one flickered back and forth between passing and failing, the other one passed.

If these are not providing spark to the wires, wouldn't that account for the sluggish rotation? At any rate, I have to replace them, now I just gotta find them.


Roy - I will pull the valve covers as suggested. At this point it can't hurt since my 24' boat is a big canoe. Thanks fellas, I appreciate the help and ideas.

 

[BlowHo]

Re: OMC 460 won't start

Anybody know where I can get a replacement Spitfire ignition system or is there an aftermarket replacement offered by someone?? Help!

 

[HT32BSX115]

Re: OMC 460 won't start

Hmmm....this doesn't sound good.

Those coils are not going to be cheap I'll bet.

You never indicated which year that is but after going to the Doug Russell site I looked at the ignition components for the7.5L engines. The 7.5L engines go from 1987-1989 (distributor ignition) and 1990 (electronic).

In 1991 the 7.5L engine does not appear to have been offered in favor of the 7.4L (GMC) engine.

This means that the 7.5L Electronic ignition was only offered 1 year. Some parts may not be available.

Click HERE For the Doug Russell ignition parts list for the 1990 7.5L engine.

If you cannot find the parts to fix it you can always go back to a distributor I guess...

 

[Coors]

Re: OMC 460 won't start

I think this is the reason that I stick with points, even though I have a brand new Mallory breaker-less in the shop..

 

[HT32BSX115]

Re: OMC 460 won't start

Here's another link to OMC parts.


Shorts Marine. http://216.37.204.206/shorts/OMC_OEM/OMC.asp?Type=13&A=28&B=10


I also found this EBAY auction

OMC COIL pack

the 914636 coils appear to be the same as the ones for the 460