Another 740T with fuel starting issues
 

New to this forum but not to many others. Have searched many threads and still not the answers I'm looking for. Maybe someone can help?

87 740T with 480k.

Ran perfect until the other day, engine turned over but not start, not even a pop.

After checking the distributor, wires, rotor, etc, checked fuel. Fuel pump not working, no fuel at the rail connection when cranking over.

Tested main fuel pump with jumpers and it pumped fine. I had a catch bottle under the hood verify flow. Psi not yet checked.

Checked and replaced fuse #1 for main fuel pump. Tank fuse also good.

Replaced fuel pump relay, no help. I did override the pump relay, grounding the dual wire under the drivers side dash, and the fuel pump operated with the key in the #2 position.

Haven't checked the radio suppression relay but don't think that's the issue without fuel pressure getting to the injectors.

Would a bad ignition switch at start position possibly be the cause?
Any ideas?

What is funny, is we are experiencing some weird intermittent Issue where the pump will shut off. I am starting to think it is the ignition switch on mine also.
I just haven't gotten around to swapping them yet. But I'm pretty sure that is it.

Thanks TipSP,

I have lots of miles and use on the ignition switch many times over the years.

Something else that also might have helped aggravate this situation... My starter recently stuck in an "open" spot where my Bendix would click but not allow the starter to turn over. I clicked my key on and off probably 20 times before the starter "caught."

Now I wonder if I overheated that starter position terminal while trying to start it?

My old start would get stuck like that. It was super annoying.
We just replaced it with a referb unit. That was like 8 years ago though.

Mines still original. As easy as it is to access, I should have probably changed out already.

It still sticks but very rarely and usually a few clicks and it engages. Not this last time, hence my ignition switch concerns.

Well today I jumped the fuel pump with a separate battery. It vibrated and made noise as normal as I tried to start my engine. Still nothing.
Now knowing I need spark to activate the relay/pump, I re-checked the distributor cap and rotor even though they're only 5k old. All looked good, clean contacts, and dry.
Cleaned the battery terminals, knowing there's two components, one direct line to the starter and the other "clump"which I believe operate the other electronics.
I then checked for spark at one of the plugs and nothing.
Strange that it rained the night before pretty good. It hasn't rained good here in CA for several years and now absolutely no fire.
I think it's the original coil and will look there next, although, I've never had a coil go bad in any of my older vehicles in the past.
Any thoughts?

Crank sensor
 

The crank sensor is the one who oprates em2 relay inside the fuel inj relay. Try cleaning crank sensor before replacing it.
:)

I'm not sure what you are trying to say here but normally a crank sensor sits on top of the bell housing and provides a signal that is input to both the ECU and the ICM. However, in this case the car in question should have the LH2.2 fuel injection system that doesn't even have a crank sensor. Instead it uses a hall sensor in the distributor to provide timing pulses to ECU and ICM. This hall sensor is a common point of failure that should be checked out. Search the forum here for more information on the hall sensor.

Well, I been under the weather this week and haven't done much to resolve. I did check my rpm gauge on the dash when kicking over the engine and no movement. Not sure if that means no signal from the Hall Sensor or not?

I checked the coil and it does have 12v on the positive #15 terminal.

I'm going to find my neighbor and have him crank it over, so I can check between both coil terminals to see if I'm getting a signal from the ignition module
More to follow.

Well, after testing the engine power module , there wasn't any signal coming from the Hall Sensor, nor any switching signal going to the negative side of the coil. Further reading, I see where the front contacts of the fuel pump relay, activate with the key "on" position and the rear relay contact, activate in the "starting" key position if the Hall Sensor is sending a signal to the ECM. The front was fine, the rear wasn't moving. I guess maybe the reason the tach wasn't working too when turning the engine over.
Picked up a new Halls Sensor and distributor with cap and rotor for almost 100 bucks.
Installed it and still no fire???
Now I checked the signal pulse from the power module to the negative side of the coil and it was pulsing. Great...move on to the coil.
Also, from pulling plug and coil wires on and off, I got myself a new wire set to avoid more issues when one plug wire fell apart in my hands.
I then tested the coil pulse coming out of the center post of the coil and we have fire!
Now I check again at the plugs and no spark? Since I had just put a new coil wire on, I pulled the distributor cap and tested continuity on the rotor- center out to the edge. Nothing?
I put the old rotor and cap back on, even though they really aren't too old and I got ignition. Finally.
Since I had marked the old distributor with the engine block and reassembled to that point, I felt it would be within a degree or two of spec.
The engine was running but no power. I then loosened the two 10mm nuts and "hand tuned" almost ten degrees advanced for testing.
All of a sudden we're back to full power!
Now I've got to get a gun just to be sure of correct timing but we are on the road again.
Thanks everyone for helping with your insight.