I have an 87, E-250, 302 , with duel tanks. I was having intermittent engine dying, while driving problems. It was as if someone turned the key off and back on again quickly. I replaced the ignition module and the two relays next to the computer. I guess one is the fuel pump and the other for the computer. A few weeks later, after driving for some time and shutting it off and trying to restart, it would just crank over but not fire up. Let sit for a bit and she fired. It didn't do it again for a while, but the other day while trying a cold start, it would just turn over. I pulled the cover and a plug wire, inserted another plug and cranked it. Plenty of spark.

I figured either fuel pump or ignition switch. I sprayed some starting fluid into the intake, cranked, and she fired up and stayed running. I switched from front to rear tank and it kept running. It sounds like the ignition switch to me, but before I tear it all apart I thought I would ask for another opinion.
When I put the switch in the run position or crank it over, I don't get any voltage to the front pump but after it starts, I get 13 plus. What's up with the front high pressure pump, as far as when it gets voltage and how? Thanks in advance for any replies.

 

Stranger and stranger .. I bought a new ignition switch and installed it today. Turned the key and it fired up. Whoo hoo, whooo hooo hooo! Not ... Tried it a few more times and it wouldn't start. I adjusted the switch, time and time again. Checked voltage at the front pump while cranking and nada. I shot some starting fluid into the intake and, as usual, it fired right up. Shut off and again, no start. Pulled the engine cover and again checked the plugs for fire. This time there was nothing while cranking.. More starting fluid and again fired right up. What the hell is going on with this thing? Any ideas??

 

Sounds like bad battery cables and grounds to me.

 

I charged it over night, turned the key this afternoon, and it fired right up. Shut it off and restarted a couple of times and back to no start and without spark at the plugs. I took your advice and pulled and cleaned the battery cables. They were in great shape, but a small black wire with a white stripe, that is also a ground to the battery, was rather corroded. I snipped the end off and soldered a new terminal on it and hooked it back up. It again started and again refused to after a couple of times of on and off. Anywhoo ... I'll dig around and look for more bad grounds. Think it might just be a bad computer?

 

Check the relays and the connections at the relays. If the EEC relay isn't seated fully or the contacts are corroded it won't trigger the fuel pump relay. Also check the fuel pump relay for corrosion on the connectors as if it's making contact some of the time but not all of the time it will do what you're experiencing.

 

Screwed with it some more this evening. Same thing. I hooked up a jumper from the battery neg to the engine ... turned it over an it fired up. Shut it off and nothing when trying to restart... no spark at the plugs. I took the connector off of the ECS, gave the connections a rub and plugged it back up .. hit the key and it fired up. Shut it off and tried again and it was dead in the water. It's like every other time it fires. I sprayed some starting fluid into the intake and it starts. Now, when I do that, I get a knocking sound that I didn't get before. Sounds like a car that has the timing set too far in advance. I even took a jumper and hooked it to the frame of the ECS and grounded it .... fired right up ...shut it off, and again wouldn't start. Is there such a thing as engine PMS?

 

I don't know what might be wrong, but if you do get it figured out, I sure would like to hear what you found out. Good luck.

 

Replace the TFI module on the distributor. When they start to fail they shut down when they get hot from use. So if it's hot when you're testing for spark there won't be any until it cools.

 

I already replaced that. Engine temp doesn't make a difference. I just turned the key, engine cold, and it started. I shut it off and cranked it over again and it won't fire. I removed and reinstalled the two relays again .... nothing. I removed them again and put the old ones back in and it fired. Removed the old ones and put the new ones back in .. fired up again. The terminals look clean and wiggling and jiggling them while cranking doesn't make a difference.

 

My buddys having the same problem with his 87 4.9l, check voltage coming out of the ballast resistor going to the dist. Checked his and found 0 volts going to the dist.