pcm 351 shuts down after warm up

hi; i hope someone can help me. i have a pcm ford 351 inboard in an 85 ski surpreme. I put new plugs, wires, cap, roter,and coil. set the timing, whts hapinning is, when its cold it starts fine. runs good but after 3 min, when it warms up. it runs rough and will just shut down, wont run,help
thank
almada2007

 

just off the top of my head maybe electric choke is wonky? clean the fuel filters maybe? sporadic electrical short in the ignition system?

 

351 wont run

thanks for the reply, i also didnt mention that it has an after market electronic ignition, the point replacment type, it also dosent use the resistor, does that matter. or could it be the ignition
thanks

 

There's only a few things that'll shut down an engine

1. cut off the electrical source for the ignition system
2. cut off the fuel source
3. cut off the combustion air supply

oh and I forgot, wrapping a mooring line around the prop (don't ask).

Sorry I don't know your specific engine so I can't really say. I've had freak things such as corroded electrical terminals on an ignition switch shut down an engine for no apparent reason. Took weeks to trace that bugger. Apparently the cigarette lighter (ver close to ign switch) had a short and slowly heated up to the point where it caused the connection on the ignition switch to expand and break connection. Go figure!

 

351 wont run

thanks rick ; could the timming do something like that,im ready to sell the boat i dont know what to do , i just started it when it cold it runs like a bear after 5 miniuts it just stumble
and stalls, steve

 

am i supose to use the resistor befor the coil even though im not running points i put i a new coil in it the boat ran perfect 2 weeks ago
thanks steve

 

put the old coil back in. Some are 6 volts and some are 12. Assuming newer electronic ign is 12 volts. Resistor would only be req'd for older 6 volt coil & points. Again no experience with that engine.

 

if you up grade to electronic ignition and left the old coil in the system then yes you need the resistor to the coil or you need to replace the coil with one that is internally resisted most all coils state on the side (use with resistor) or (do not use with resistor)

 

I assume that it's a carburated motor being an 85.
Have you done any carb or intake work to the engine lately.
I've heard of people having issues with a spacer between the intake and carb that will transfer enough heat to the carb to cause the fuel to perculate.
They need to put an insulated gasket in to solve the issue.

 

Yeah I'm with rivrlivn on this one- it sounds like once the engine is hot, somehwere the fuel system is heating up enough to vaporize the fuel- could be the carb, or a metal fuel line, and that is causing crappy running.

 

351 wont run when hot

thanks for the replys, im changing the electronic ignition today,when i took it out it was so hot i coulnt even touch it, i dont think it should get that hot, if that dont work im going to go into the fuel, but i did read another thred in another section , someone said to run a wire direct to the coil to see if there is a break in the ignition wire, thanks steve

 

351 runs crapy

i changed the electronic ignition but still the same problem, but i went to the fuel and saw that my fuel filter doesnt stay full when its running. is it supposed to be full when its running, it might be the fuel pump???? or a bad pick up
steve

 

Although the fact that it does run good when cold for a few minutes isn't too indicative of an engine not receiving enough fuel, it wouldn't hurt to make sure your filters are clean, and that the pump is pumping enough volume. I would disconnect the fuel line at the carb and put it in a clear bottle or container, and have someone crank the engine (with the coil disconnected) for about 10 seconds to see how much fuel comes out. Also, you could buy a small in line fuel pressure gauge and itshould read between 7-10 psi when connected between the pump and carb

 

351 runs awsum

thank for all the help on this one ,but i found that the gap was to big at the electronic pick up. i gaped it to .10 and it runs wicked the 351 has grazy power. i pulled tubes all day it runs perfect. and realy thanks for all your input.
steve

 

Jeez, had us all wrong LOL. THanks for the follow up!