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I have seen posts similar to this browsing around but can't seem to find exactly what I'm needing again. So, sorry in advance for a duplicate post if it is.
I have a 1990 F-150 4.9 that has been sitting for about 7 years. It was my wife's grandfather's. My son and I are trying to get this running and back on the road.
I had a post a couple of weeks ago because when I popped the hood for the first time, the starter relay was completely disconnected and sitting on the battery.
So, I figured someone was working on something but just didn't know what and nobody else does. So, my first post was getting that hooked back up. It now cranks with a new battery, plugs and wires but won't start.
I'm pretty sure I'm getting spark because it turns over for a second with starting fluid. I can test further if recommended for spark but figured it must be fuel if I had that first turn over.
It has dual tanks. I have just replaced the fuel filter as I'm going through all of the stuff I think should be changed from sitting so long.
What I probably need help with is diagnosing if it's fuel pumps, selector switch or something else I didn't know about. Also, I just noticed the selector switch fuse was missing so I put one in but still won't turn over. That probably indicates whoever was working on this before got to some point of diagnosing the selector switch??
Any advice on where to start diagnosing? I've seen some posts about testing power at the fuel pump relay but I think they were checking specific other things and it wasn't quite my problem. Any advice would be great!
Sounds like you did not get all of the fuse links back on the battery side of the starter relay.
These fuse links feed the power relay and the fuel pump relay.
Ok. I can now see where I find the posts I've subscribed to also. Sorry, new guy here. I didn't see any other loose connections out there and everything that was loose when I got the truck is now on the battery side except for the starter. I'll go back out there with the diagram on that post and check them one by one. Do those have inline fuses? Can I check those if they are all in fact connected to the relay?
Ok. So I should be able to test connectivity between the yellow links at the relay with a test light and the other end at the fuel pump relay, correct? The yellow links are on the post with the battery on the starter relay. If you look at that other thread you helped me with I put a final picture of my connections (https://www.ford-trucks.com/forums/1...-ignition.html) if you can check my work. I would appreciate it. There is a bundle of yellow links and a green link on the right side post with the battery. Does it look correct?
I can not tell too much from the photo.
The yellow wire at the relays should be hot at all times with the key off.
Just use a test light at each relay between the yellow wire and a good ground and it should light.
Is not the start of each yellow wire at the starter relay a different color?
Maybe it starts out as blue or brown.
I thought they were all yellow except the green one but they might just be dirty and I assumed so. I'll clean them off when I get home in a couple hours and see. I'll also see if there is power at yellow on both relays. I don't see the yellow one to the fuel pump relay on your diagram though. It must be on a separate one.
Oh ok. I see. I did order a manual that will hopefully have some of these diagrams. Won't be here until tomorrow. But, not sure I'll understand them at first! Looking at this one, the fusible link going to the fuel pump relay says 20 GA BLUE in the box but I thought it was yellow. Is the Y across from the 37 the actual color of the wire? What does the BLUE indicate? I appreciate your help. I've been looking around different posts here and you are a wealth of knowledge and help so many on this forum.
20 GA Blue is the fuse link and is hooked to the starter relay.
Yes the Y across from the 37 is the actual wire color from the fuse link to the relay socket.
The yellow wire is hooked to the blue fuse link near the starter relay.
OK, so I just tested the links connecting to the starter relay and all have power with the key off as expected. The yellow line going into the fuel pump relay also has power with key off. For some reason, it is how it looked: all but one is yellow (see closeup picture #1) so someone must have replaced them at the connecting end. I followed them into a bundle that leads between the battery and the frame and they look more like different colors when they come out of the bundle (second picture).
Last edited by BeetleB; 06-22-2018 at 05:11 PM.
Reason: Lost the text
That top dark area you have pointed out is the same green one you're pointing to in the bottom of the picture, just looped out and back into the picture. I tested all of the links on the other side of the bundle where they are brown and they all have power. With yellow in to the relay having power, do I now turn the key and check another wire at the relay? The red doesn't have power with the key off.
The red wire will have power with the key in the start or run position.
The red wire at the fuel pump relay feeds the coil of the fuel pump relay.
The red wire is powered by the power relay with the brown bottom.
Did you check for power on the yellow wire at the power relay?
The red wire at the fuel pump relay does have power only when the key is on. The yellow on the EEC power relay has power with the key off (both of them, there are two). The red going into the power relay has power with the key on also. Is this the correct relay with the brown bottom?
06-21-2018, 05:27 PM
