1991 4.3 OMC wont run

[definitiveaqua]

Just bought a '91 chris craft and can not get it to actually run for the life of me. I bought it with a broken exhaust manifold and starter. I replaced all of that as well as the plugs, wires and rotor (cap is not here yet but ordered). Engine has fuel and compression ( didnt actually test it but when you turn it manually it seems like it has good compression) ignition has spark.

It currently will crank but not start it just misfires out of the carb every so often. I have tried adjusting the timing as well but it just wont run right...

suggestions?

 

[gbeltran]

Re: 1991 4.3 OMC wont run

"( didnt actually test it but when you turn it manually it seems like it has good compression)"

Then you don't really know for sure. Did you get the wires in the correct order? Points set properly?

 

[definitiveaqua]

Re: 1991 4.3 OMC wont run

wires are set correctly even manually cranked and checked with a straw because I thought maybe i got it wrong. it almost seems like the distributor is 180 off but it cant be because of the wires and the markings plus I never took it off. this motor doesnt have the points system tore the distributor down and checked. under the plate there is what looks like two large magnets or pieces of metal and a spring.

 

[definitiveaqua]

Re: 1991 4.3 OMC wont run

well after scratching my head I went through and checked the plug wires and there was one out of sequence but she still wont run. now it just cranks.

 

[gbeltran]

Re: 1991 4.3 OMC wont run

Under the plate in the distributor is the advance mechanism. What's on top of the plate? There can't be just one wire out of sequence, minimum would be 2.

 

[Joshua Nichols]

Re: 1991 4.3 OMC wont run

So now you are sure you have the correct firing order?

Got spark.. Only fuel and compression left...

Open up the throttle to WOT.. Give it a shot of carb cleaner and see if it will hit a lick..

 

[donberry]

Re: 1991 4.3 OMC wont run

only reason a engine won't run is fuel (includes air/gas ratio) or spark. Since it is an electronic ignition, if you are 1000% sure the wires are now hooked up correctly, depending on what kind of ignition it is, could very well be the ignition has failed. Not a whole lot to those but when they do go bad, they go bad. The one big advantage to points. I may want to test my coil first though
See if you can't figure out what type of ignition it is then you can look up the owner's manual for it. May be stock or something like a Pertronix.

 

[airdvr1227]

Re: 1991 4.3 OMC wont run

You might be finding the real reason the last guy sold it. Any chance of asking him?

 

[Joshua Nichols]

Re: 1991 4.3 OMC wont run

You might be finding the real reason the last guy sold it. Any chance of asking him?

Yeah like low compression...

 

[definitiveaqua]

Re: 1991 4.3 OMC wont run

Well spent the whole day messin with it and found out whats wrong....

1) I had put NGK platinum duals in and had the damn wires right but somehow messed up and switched 3 and 5 around. Fixed that and put Delco spec'd plugs in just because I wanted to make sure that wasn't the issue.

2) Ran a compression test - got 150 all day long on every cylinder.

3) Noticed that at first I thought the plugs were being washed in gas because it sounded like it was flooding itself.... turned out to be water in the combustion chambers of 1,3,5.

So pulled the exhaust manifold to check and see whats going on... disconnected the coil and tried to turn it over - gushed water out of #3.

Now with everything disconnected I suspected that maybe it wasn't winterized properly and we had a cracked head so tore the whole motor down...

Found the source of the problem - bad head gasket and cylinder 3 full of water. Water was basically being pushed from 5 to 3 back and forth is all I can assume because all of the rods lifters and everything else seem to be in fine condition.

Will be installing a new gasket kit on everything, do another oil change and then she should be ready to go!

 

[gbeltran]

Re: 1991 4.3 OMC wont run

You also need to check the exhaust manifolds to make sure they arent leaking water.

 

[Joshua Nichols]

Re: 1991 4.3 OMC wont run

So started off.. Had a bad starter and a broken exhaust...

Now it is suspected that it wasn't winterized..

Blown head gasket..

I would check for a cracked block before I put too much else into it.. It could just be a blown head gasket. Blown between two cylinders and a water jacket(strange).. My money is on the cracked block theory..

 

[definitiveaqua]

Re: 1991 4.3 OMC wont run

Manifold and gaskets are new.

Engine has tons of compression and there are no signs of a cracked block. head gasket failed probably because the exhaust manifold failed and caused it to not properly cool... at least thats my theory... could also just be that its an old motor.

Pretty sure the guy I bought it from just purchased it broken from the old lady whos still on the registration with the plan to try and fix it and he never did. But he B.S'd me and said he knew what it needed.

 

[Joshua Nichols]

Re: 1991 4.3 OMC wont run

Engine has tons of compression and there are no signs of a cracked block

Hard to tell if they are cracked.. You have to pressure test the cooling system.. It can have compression like a new engine and still be cracked.. It will run good with a cacked block too... Right up till water and oil shoots out of the breathers on the valve covers...

Hope ya got her cheap... Post up some pics of her...

 

[definitiveaqua]

Re: 1991 4.3 OMC wont run

Just got done taking her for a run Runs like a champ!

Ended up changing all the gaskets on the top of the motor just for good measure.

And yea I think I got a pretty good deal 3k interior and exterior were mint and everything (besides the motor lmao) was in perfect working order