The pumps do not run with the key. The only time the pumps run is either by grounding or jumping terminals or direct 12volts to the pump. When the key is turned there is a click noise heard after about 2 seconds...maybe a timer of sorts for when the pumps run but during all this troubleshooting the pumps are not running with the key.

 

Is there a fuel pump fuse at the under dash panel? I have been looking for a diagram and so far for a 91 I have not found anything showing a fuse pump fuse at that panel. Heres a question..should all 3 pumps run when they key is on it when I jump or ground relays? I ask because so far the only pump we hear is the one up front on the frame rail.

 

The power that is supplied to the fuel pump relay terminal that is hot all the time is supplied by a fusible link probably off the battery terminal on the hot side of the starter relay on the firewall or fender well. It is usually blue and rated for 20 amps.If the pumps run when the relay is jumped (terminals #2 & 3), the link should be OK..

Depending which tank the selector is set on , that low press in tank fuel pump AND the hi press pump on the chassis rail should run. Don't forget if you are just turning on the key both pumps should run for the usual 2-3 seconds. You can hear if the in tank pump runs by placing your ear close to the fill hole.The computer allows the relay to close and if it does not get a signal from the ign system RPM , engine started, it opens the ground to the fuel pump relay and shuts off the pumps.
It sounds like everything is working as it should , does the truck start and run?
If it cranks over and refuses to start, remove one of the spark plugs and see if it is wet or dry. If wet it is either flooded or a no spark condition and if dry fuel is not getting to the jnjectors or the injectors are not working. Which condition do you have?

 

When I turn the key on the fuel pumps do not turn on. When I crank the engine obviously they are not turning on then. I did ground out the test connector again and I verified the intake pump in the rear runs. I'm pretty certain the front is running as well. It's kinda noisy where we are at and that rail pump is so loud it drowns out everything...but I can hear fuel sloshing around in there as well. The engine will start as ndvstaybrunning if i leave the test connector grounded. We shut it off after a few seconds cause i didnt know if it was ok to run it that way. So bottom line ..in the same situation that the van was in 3 months ago...it cranks but no fire. This diag procedure started 2cdays ago. During the course somewhere a test showed a bad fuel pump relay, even though einstein said he checked them and I was wasting my time. New relay was then purchased. He also claims that one ofvthecrelays was replaced 3 months ago so in theory 2 new relays. I assume with the results we are at your going to say it's a bad relay which is why I've given the background why they are new. Yesterday I bench tested the relays and they test as good. I put 12vvolts to terminals 85 and 86 and the relay clicked. I then checked for continuity or resistance (not sure the proper terminology)between 87 and 30 and they checked good..just giving you as much info as I can.

 

You can run the engine that way, you just lose the protection of shutting down the fuel if the engine stops. Not recommended , but you can run it to charge the battery if necessary..
The EEC and fuel pump relays are the same . They can be interchanged if necessary.
A little side info, you can remove the cover on the relay and see what is happening inside if you choose. Just be careful with a small screwdriver when lifting a side at a time of the cover.It can be replaced the the same way.
The problem now, as I see it,is to determine why the computer is not sending the ground to the fuel pimp relay which we know is working because it is closing when you ground the test terminal.,but not when the key is first turned on.and when cranking the engine over.

I can give you pin numbers to check, but would rather do some quick visual checks first.
Loosen and remove the 10mm bolt that holds the plug on to the computer(ECA) located under the battery on the passenger side firewall . Look the plug over carefully for any corrosion and clean with some WD40 if necessary and retry starting. If no success,then we may need to see if it supplies the ground when the key is first turned on . If you need the pin numbers, I can supply them.
We would first check at the #1 terminal of the fuel pump relay plug for a ground coming to that terminal when the key is first turned on. Either you will get it or you won't ,and we go from there back to the computer. We would verify the wire from that pin position on the plug that goes to the fuel pump relay is good and if it is the problem lies within the ECA.

 

I have checked for ground at the 1 terminal from the computer. If you go to that diagnostic page I posted you can check test 4 to make sure it was done properly. According to the test I did there was a ground at that terminal.

 

You should be getting a ground from the computer when you first turn the key on at TERMINAL #1 on the plug not 4 The relay must be out of the plug when doing this check.

 

I am getting ground at terminal 1 with the relay not plugged in. So far every test I have done I has given the the result that we have been looking for with the exception of 1. There is not 12 volts at #3 with the key on or cranking. We have swapped relays, and even tested relays and they test good so in theory there should be 12 volts present and it should start. If I ground the fuel pump pin at the test connector it runs so at this point I'm thinking of leaving it like that or running a switch at that terminal and calling it done. Not sure what else to do. I suppose I could get 2 more relays, even though bench test good and test good in the car up to that point. One relay was bought new 3 months ago and the other just a few days ago and it be my luck that both are bad at the same time but have to think it's something else going on. If there is no voltage at #3 could it be anything else but the relay? If the computer was the problem would I have ground at # 1 terminal still? From what I understand that's the signal from the computer so again, in a perfect world this thing should start.

 

You must get that ground to the fuel pump relay when you first turn the key on. It is for 2 seconds only.
Is that at least happening?

Now you turn the key to the start position and UNLESS THAT RPM SIGNAL FROM THE IGN SYSTEM IS RECEIVED BY THE COMPUTER IT WILL NOT SEND THAT GROUND DOWN TO THE FUEL PUMP RELAY.
We know that is happening or the engine would not run anytime.
The "running" ground to the fuel pump relay comes from pin #22 of the ECA.
One last check you can do is connect the red lead of the meter to the battery + terminal. Then connect the black lead to terminal 1 of the fuel pump relay (everything in place) and crank the engine over. If the meter does not show that terminal is getting grounded,Replace the ECA.

 

Ok, first off I have to thank you for your help this far. I did like you said... positive lead to the positive battery terminal and negative lead to the #1 wire at the relay contactor with it plugged in. It actually showed 12 volts with the key off.. then turning the key to on it dropped to zero and off course stayed at zero when cranking. I think where I screwed up is a few days ago when i tested that wire per the website with all the testing procedures we didn't crank the engine. I think I over looked that part. When we probed the wire and it lit the test light I believe we assumed we were good. So technically it failed that 4rth test but we have been trucking right along as if no problem. Sip the problem is not getting 12 volts at the#1 wire with key on or cranking. So this means the computer is not grounding the relay correct? Which would explain why when we jump the relay our ground the test plug the fuel pump runs. Stubborn father in law replaced the computer a year ago which the van ran for a few weeks and then stopped. Since he replaced it then he doesn't think necessary to check to make sure there no corrosion now cause it was fine then. I'm taking it out and gonna check it all out and let you know. I hope it cleans up and runs and I will try to get the look on his face when it starts and I say told ya so...lol.. thanks