Need Help on 1972 280 SEL 4.5 THAT WON'T START

[bpacheco55]

Changed computer, car ran GREAT, put away for the night. It rained all night, but car under a canopy.

Put other computer back in to see if it would start and it didn't. I then did the following:

• Checked fuel pump pressure and delivery to injectors, gas was evident, however, found no power to the Cold Start Valve,
• Supplied power to the CSV while cranking engine remotely; no start,
• Checked points, condenser; points got 13 volts;
• Coil is getting 13 volts (both sides);
• Checked spark plugs wires for voltage to plugs; voltage was evident
• Pulled plugs after activating CSV, bypassing the ignition activation, while cranking engine and found evidence of gasoline being delivered to the cylinders; still no start,
• Checked injectors while cranking engine with stethoscope; all injectors were clicking,
• Checked distributor for timing; set at top-dead center; still no firing

Puzzled that there isn't even an inkling that it is trying to start. Don't know where to go from here except relays but haven't a clue where the CSV relay is. Is there anyone who knows this answer? Anyone who has an idea what the problem might be and what to do next. I'm stumped.

Thank you in advance.

[murdockspencer]

• Checked spark plugs wires for voltage to plugs; voltage was evident

What do you mean by this? Are you getting a spark that will ark out of the end of the plug wire? From your post it sounds like you have no spark. If you had spark but fuel dilivery problems it should at least cough a little bit for you. I had this problem with my 4.5 and it turned out some gunk got onto the distributor/points cam and the points weren't closing all the way. They looked fine at first but when I looked closer they weren't closing so make sure you have spark. When you are absolutely sure you have spark, spray some starter fluid into the air filter and crank it again, if it fires, I would suspect the fuel pump. Make sure it's turning on. You can still have enough fuel in the system to give the appearance but actually have no pressure.

[alabbasi]

Unless it's freezing, you shouldn't find power to the cold start valve.
Could the engine be flooded?
Check to see if there is gas in the oil. These cars have running rich issues when the computer/map sensor is misbehaving.

Good luck.

[carnut]

I'm confused? if the car ran with the exchanged computer and doesnt run with the other one why test all these other things? just replace the computer! What am I missing?

[Tomguy]

You didnt say you put the known good ECU back in. I'm assuming you did however, as the rest would be moot if so. Now, just because you can hear injectors clicking doesn't mean gas is being delivered. You may want to verify that it IS by actually checking the injectors. It may be that your CSV vented the fuel into the CSV system and that put gas in the cylinders, but there is no pressure in the system to start the engine.

You only changed the ECU. Therefore, it must be a fuel issue. Verify you have 30PSI at the fuel rails while cranking.

Edit: And keep in mind, if you're flooded, best bet is to unplug the trigger point harness and CSV, and crank with the throttle to the floor. It may backfire a few times, but crank it for about 30sec and then try starting.

[alabbasi]

If the engine is flooded, the disconnecting the trigger would be a good way to go to burn off the unwanted gas. I blew up a tail pipe that way :-)

If it was me, I would drain and refill the oil instead.

[230/8]

BP...55:

Everyone's time is being wasted until there is an answer to carnut's question. If it ran fine after exchanging the ECU, why did you change it back and then start testing all the other stuff? Sounds like you had the problem aced...like carnut, I want to know, what am I missing?

230/8