Hello, I am new to this forum, but I hope someone can help me figure this out.

I have a 1986 W250 power ram pickup with a 360 four barrel. It has a problem starting. Turns over just fine, but can't get it to fire, except for a brief moment when the key is turning off. I have replaced, battery, cables, starter, voltage regulator, Ignition switch. It has always had this problem, but would usually start on the third or fourth try. Now It won't fire at all. Is there some type of relay, or electrical connection that could be at fault. I suspect this because once it starts, it runs just fine? It has new plugs, wires, and rotor.

P.S. This truck has several other electrical issues with the gauges, radio, blinkers, brake lights etc. The guy who owned it before me did a lot of add on electrical, most of which is gone now. It also may have a slow drain on the battery. Can anyone suggest a possible cause?
Thanks, Tobias

 

Do you have good spark at all spark plugs? Does it turn over slow?

 

Yes, It has good spark, and turns over like a champ.

 

Note: It has good spark when it fires, which is the problem, it won't fire.

 

Is there fuel getting to the carb and being squirt through the jets? Are the bowls full?

You need three things for it to start and run; fuel, spark/timing and compression.

 

again, all seems to be well if I can get it to fire. I turn the key, it cranks, no firing, and as soon as I let off it pops, but just once, and by this time the the started has disengaged, and won't keep firing.

 

I have replaced the ignition switch twice, so I don't think that is the problem, but I have been wrong before. Could it be something with the electronic spark controller?

 

also, I have heard that there may be a fuel valve relay, do you know anything about that?

 

Just checked the ignition switch- good, and replaced fuel filter which has probably never been done. I think at this point the engine is flooded. Strong gas smell when cranking.

However it still fires on the backstroke of the ignition switch turn, but only once.

not sure what my next step should be, but I am leaning towards tracing a couple of wires coming out of the ignition switch.; namely wire #6 (black with copper connector), #7 red, #2 yellow, and #4 dark blue.

These are all the connections that need to be made in start position of the ignition switch.

All of the switch contacts test fine in accessory position, run position, and start position. If the switch is functioning properly, it could be a broken wire, or corroded terminal, most likely on the start position wiring. At least this is the best I can come up with.

If you know anything about this issue, or have had similar problems please let me know, Thanks, Tobias

 

Have you checked the ballast resistor

 

I checked the ballast resistor. It measured about 1.6 ohms instead of the recommended 1.2 ohms. Is this enough to cause a problem. I replaced it about three years ago when it completely fried itself.