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91 e350 5.8 fuel pumps not turning on

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  #31  
Old 03-28-2020, 08:15 PM
Brandon Montana's Avatar
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I'm not sure you mean by do my references match my wire colors but I can tell you this..based off what you told me about the eec relay clicking when the key is turned, and the fact that website shows fuel relay has a green connector and the brown connector as the eec and even though the colors of the wires dont match, thevterminals getting tested seem to be giving the right results that everything points to the relay we have been testing is the right one. Did you get the link to the pic I attached in my previous reply? If not go check. It's a pic of my relays and wiring so if you have any questions it's right there for you to see. I will send again...also I sent the link to the site I'm getting all my diag info from so you can check and see if something is not right there. For the heck of it maybe I will perform the same diag procedure on the other relay and see what happens.

https://photos.app.goo.gl/6dNEyXALko27eHJA9

https://easyautodiagnostics.com/ford...-relay-tests-1
 
  #32  
Old 03-28-2020, 09:39 PM
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The reason I wanted to know the exact colors was so we were sure when we expected a particular result from a terminal of one of the relays we were on the correct location. As you can see , it can get a little confusing both being in different places . Let's see if we can get this problem solved. Thanks
 
  #33  
Old 03-28-2020, 11:52 PM
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Originally Posted by hanky
The reason I wanted to know the exact colors was so we were sure when we expected a particular result from a terminal of one of the relays we were on the correct location. As you can see , it can get a little confusing both being in different places . Let's see if we can get this problem solved. Thanks

Did you see my previous response where I told you which color wires were going to each of the relays?
 
  #34  
Old 03-29-2020, 07:15 AM
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From the wire colors you provided this is what you should have , what should happen and when.

EEC Relay
Blk/Org should be hot at all times comes from starter relay
Blk/Grn should be connected to ground
Red/Gn should have power when key comes on
Red should provide power to system AND positive terminal of Fuel pump relay coil

Fuel Pump Relay
Yellow- hot at all times , comes from starter relay
Red- gets power from EEC relay when key is on
Dk Gn/Lt Grn- should be power out to fuel pump
Blk/Org- a-2 second ground from ECA to neg term of relay coil when key is first turned on
b- Ground for relay coil when engine is running
c-Ground for relay coil when test terminal is grounded with key on

This is probably what we should have done from the start, but let;s go from here.
If you don't have/get the readings suggested , tell me what else you are getting that is different from what I have posted, thanks

 
  #35  
Old 03-29-2020, 01:28 PM
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The only thing I'm confused about is the a,b,c on your last post. What did you mean by that?

Blk/Org- a-2 second ground from ECA to neg term of relay coil when key is first turned on
b- Ground for relay coil when engine is running
c-Ground for relay coil when test terminal is grounded with key on
also..in the diag from the website it mentions #4 on the fuel relay(yellow) is powered when the key is on. You mentioned it should also be hot? I just want to make sure that is normal because #4 wire on my fuel relay and eec relay are both hot at all times. Wouldn't it be safe to say that if I have voltage at the inertia switch that everything with the relays powering up and grounding must be good or that would not have voltage? If I remember correctly the other day we had only 7 volts at the switch with it un plugged and key off. Plugged in with the key on and cranking we had nothing. Just thought I'd mention this I'm gonna check everything again based off what you sent me...just need you to clarify the a,b,c
 
  #36  
Old 03-29-2020, 03:59 PM
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The fuel pump relay coil has to receive a ground connection in order to close the relay contacts. If no ground is provided , the relay cannot work., No relay closed ,no fuel pump operation.
As you recall , The relay coil can get a ground by,
(a) - for 2 seconds when the key is first turned on (To prime the fuel lines to the injectors with fuel pressure for quicker starting)
(b) - the ECA when it gets an RPM signal (Engine cranking/running)
(c)- - grounding the test terminal with the key on.

With this information you should be able to tell what you have or don't have at the terminals and when and be confident everything is working as it should by the relays.
You can use a voltmeter to do these checks , but a test light is quicker and some systems have a resistor in the line to the F/P hot supply and you could be getting thrown off by that reading.
You by-passed some of these requirement conditions when you jumped the relay. All you need to do now is determine which requirement is missing.
 
  #37  
Old 03-29-2020, 04:10 PM
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Ok...I dont have the answer why the results today are different than yesterday. All i can tell ya is it's been real rough with my partner who is in control of the volt meter and test light and wants to check the radio fuse cause it could be on a parallel circuit that may be grounding the rear window defrost wire causing the cup holder to close which is possibly supplying ground through the glovebox light...well we dont have glovebox light so his theory is wrong. I'm obviously joking, but you see what I'm dealing with. I figured what you meant with what these relays do. I am getting some contradicting information here. So, everything you said as far as the eec relay is concerned is good. The wires are supplying ground or power all the time or with the key on or as a service advisor for many years I would be saying the eec relay is working as designed. As far as the fuel pump relay goes we have power all the time at yellow #4, red wire# 2 has voltage with the key on, the dark green/ LTE green #3 wire has no power when cranking with the relay connected, the#1 blk/orange wire has ground all the time with the relay connected. It drops ground with the key on or cranking. If we run the jump wire to the test connector we are getting ground on the #4 wire and also getting power at the #3 wire. If I understand what's going on here is the computer is not supplying the ground. It's only when we supply through the test connector are things working somewhat properly. So I am assuming the problem is the actual computer?
 
  #38  
Old 03-29-2020, 05:43 PM
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Well..I know all that I just dont know how to figure it out. What if i just run a ground direct to terminal 1 of the fuel pump relay? Wouldn't solve my problems? I know it wouldn't be the proper fix but the engine would start
 
  #39  
Old 03-29-2020, 06:05 PM
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You could be right, but we need to confirm this is so before condemning the computer.

When you ground terminal #1 (Blk/Org) with the key on the relay should close , power from #4 (Yellow) goes to terminal #3 (DK Grn/Lt Grn)...
Terminal #1 should provide a ground when cranking ,if the ECA is sending it AND the ign system is sending an RPM signal to the ECA.. If that is not happening you need to confirm the wire from terminal 1 (Blk/Org) that comes from pin #22 on the computer is not open or has a poor connection at the computer. If the ground at the computer itself is missing , it can't send that ground so make sure it has a good case ground. Do what you have to in order to check that wire at the computer plug. Find that color wire coming into the plug and stick a straight pin in it and see if it is sending a ground , if not then I would consider replacing the computer.

Remember, the main purpose of the ECA sending a ground to the FP relay is to prevent fuel spillage in the event of an accident or mishap if the engine is not running and the inertia sw fails to work. You can do what ever you choose in regard to by-passing the ECA, that is up to you.

 

Last edited by hanky; 03-29-2020 at 06:12 PM.
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