Logo
FULL SITE MENU

rebuilt 1990 454 will not start 23' thunder bird

I

irefrige

New member
hi, i have a 1990 454 merc cruiser engiine that i had rebuilt from a good rebuilder this engine came out of this boat and was running just tired like it's owner.i put engine together and i installed in boat. this is about 4th engine i did and never had a problem.i have a thunder bolt ignition which i checked by the book and it checked out ok.i had a mechanic come over and check valves and timing and was told my distributor was the problem even though i had spark at plugs. i got a auto, one wire hei distributor and tried that got same will not fire on turning over.the engine turns cw and the distributor also had no 1 tdc, rotor pointing to no.1 plug and 1 on distributor,all gas lines,filter,pump and tank were replaced or cleaned. i took off timing chain cover for mechanic to look at to check timing marks with no.1 piston up he said it was ok. this engine turns over ok.and i get good spark. just covered for winter, had dusting of snow if i get a good day i will look at it this winter. i would like to get this engine just started to have for next season. any help would be great thank you
 
Re: rebuilt 454 will not start 23' thunder bird

maybe i missed something exactly what do you want to know ?

What is the problem ?

example: boat doesn't start ?
 
Sounds as if you did everything the right way. Sorry to hear about the dusting of snow but, I know the feeling.

The primary thing you did not mention was gas. Based on your testing and checking there was no mention of the fuel? Whatever is in the fuel tank now may already be dead or on it's way to being that way. I hope you treated the fuel AND I would absolutely test the fuel by filling up a jar with some to examine any separation.
 
180 degrees out? Just cuz the piston is at TDC does not mean it is in correct time. Piston must be in TDC during compression stroke not exhaust stroke.
 
Why i didn't understand this op the first time i replied is beyond me.

You got a kill switch on this boat ?

Want to try something a little different ?

Give power straight to the coil from the battery. Leave the keyswitch on and jump the starter see if it starts.

This is a carbed motor?

Electric fuel pump right ? If yes you got juice to the pump ?

Not chiding you bit never install a motor before you had it running on the crate .

Then you could have jumped the pump, still can.
 
thank you for reply, the first thing was gas, i cleaned tank,blew out line,have new fuel pump & new fuel lines,put fresh gas in tank. engine is getting fuel it seems as if the timing is out. the engine is blowing back thu carb a little. i think i have run out of things to check. but i won,t give up till i hear this running
 
hi chief i'm at the point of eliminating everything i can. i even tried a one wire wire hei distrib. and no results. chief i have never run in to something like this before i have changed engines on this boat 4 times since i have had it, and never any problems but in the future i will start it on ground to be sure. i tried power direct to coil, has a new fuel pump,and getting clean fuel i think it is in timing some how as it blows back though carb when trying to start i thought starter was going wrong direction as this is new. i'm going to check this again as i asked someone else to let me know which way it was going as i cranked engine ? will let you know how i make out thank you chief
 
removing the timing chain cover and inspecting the timing dots has NOTHING to do with piston position.
Did the 2 dots line up properly?
Did you set the dist in correctly with #1 on TDC compression and installed dist with the rotor facing any particular post?
Air sounds from the carb indicate a valve timing issue or very tight valves ,what are the compression numbers?
turns clockwise viewed from the front of the engine
 
Sounds like you have a no 1 tdc problem get piston on comp stroke then ck chain marks also dis should be at no 1 also ck rotation of eng the other guys seem right on good luck
 
Why do we hear about problems of rebuilt motor after they install them in the boat but do not start it on a crate or pallet first ?

This is happening more and more.

People start the motor out of the boat.

Having spark at the plugs is one thing having it at the plugs at the right moment is key.

The right cam in the motor, the right, crank ? The dist set up correctly. Timing chain hooked up right all done on a crate. Not in the boat.

Blowback out the carb would suggest one of the above is setup wrong.

Back to basics, checking and rechecking everything out of the boat.
 
I agree bad valve timing........He has spark, he has fuel, he has no ignition...............What is missing? COMPRESSION.

you need three things

fuel
spark
compression

with these three things, the spark must happen at the right time if it does the valves need to be closed to accomplish compression (assuming rings are good) and if that happens all at the right time then adding fuel to the mix the engine should roar to life.............
 
1. Remove spark plugs
2. Put finger over # 1 spark plug hole
3. Rotate engine till you feel compression on #1 (if you feel vacuum on finger, you went too far)
4. Look at timing mark on vibration damper / timing cover tab.
5. Continue rotating slowly till timing marks aligned at "0".
6. That, my friend is TDC. #1 piston on top of stroke with both valves closed.
7. Align distributor to #1 sparkplug. Ensure plug wires are set to firing order is 1-8-4-3-6-5-7-2 in a clockwise direction.
8. Re-install plugs.
9. If all this is correct AND you have "GOOD" fuel, AND suffucient DC voltage to system with a strong spark to plugs,
AND timing chain marks are lined up (as you said), the engine will usually start, unless there is a major problem, like a big hole
in the intake manifold somewhere, a bad rotor / distributor cap (these are common problems) or something like that.

The engine would, in all probability, start, even if there was a blown head gasket or something like that, but run like crap.
Try to stay away from starting either, if you haven't used it already, as it washes oil from cylinder walls and makes compression way too high.

I know this is odd, but gotta ask.... Is this a right hand or left hand rotation engine? I only ask because a friend purchased a right hand engine and it was actually a left rotation, set distributor for right rotation (what he thought he had) and guess what...... No fire.. Took a bit to figure it out. Only summised when we spun motor with starter, without dist cap and rotor was spinning wrong way. DAH _
 
Last edited:
Exactly what I am thinking. Simple mistake happens more often and causes headaches more often than people think. I don't know how many boats / autos with dead engines were brought to me over the years because someone ripped all the plug wires off or pulled the distributor without ensuring TDC, then reinstalled 180 degrees out.
 
Back
Top