Good morning from the north east, my name is Dan. I’m having a fuel issue. The problem presented itself yesterday and since then I’ve spent my time reading this great pool of info. I found a thread from 2014 where the op was having a similar issue but not everything lined up with what I’m experiencing. I will link that thread after I describe my circumstances. 1990 E-250 with the 5.8. It’s a cab/chassis that was “incomplete” and sent to gulfstream rv to be fitted with one of those economical towering fiberglass high tops and various cabinetry and plumbing/wiring. Searching the vin comes back with “1990 E-250 cargo van super” and “incomplete”. It has dual fuel tanks.

When I got the van the previous owner had bought two in-tank pumps hoping that upon replacement he would solve the issue of the front tank (while running the engine just fine) also feeds gas to the back tank. He replaced the front pump but didn’t get to the rear. Don’t worry, the back feed isn’t the issue I came here for lol. I found tons of threads on that. So fast forward to yesterday and I wanted to replace the rear pump because why not, after all he gave it to me with the van. Dropped the tank and replaced the pump with no issue. Now, before I go on I’d like to say that I’ve also been experiencing that frame rail fuel pump thing where it runs longer than it should before priming but lately it hasn’t been happening. I’ve read a metric s@&t ton of info on that too. So anyway, I finish the rear pump and the moment is here! Try to start it! It started and ran! Hooray! One minute later my buddy says “there’s smoke coming out of the hood”! So, one of the very small wires that runs from the ecm relay to the starter solenoid melted close to the starter solenoid end. They’re two really small wires that are joined at the end by the same loop connector that goes on the solenoid stud. I cleaned up the wires and crimped a new loop on the end and tightened it back on the solenoid.

While chasing wires I noticed that the brown relay, which I understand to be the ecm relay, was very corroded. I bought a new relay for it and a new fuel pump relay, which I understand to be the green one, even though it didn’t appear to be bad. Turn the key and no frame pump priming sound. It’s always very noticeable. So still a no start. I found a thread with instruction on how to test the relays and pumps using the self test harness. I grounded the #6 pin and the green relay clicked but no frame pump and I was alone so I couldn’t hear the rear tank pump but assume it’s working since the van did run for a couple minutes after replacement. Jumped #2 to #6 and green relay clicked but no pump again. So is my computer and the frame pump bad? Ecm ground looks good. It’s still the oem terminal end where the ground is molded into the lead of the terminal. The connector end of the ecm relay looks like some corrosion in there. The female part that the relay goes into. Thinking I should pull these wire ends out and crimp fresh ones? Looks a little crummy but does look good enough for electrical current to pass through. Pretty sure the guy said he replaced the frame pump while he owned it too but maybe it’s burnt out from running so much when priming? The no prime issue has never left me stranded. It always ends up shutting off/priming. But I’ve owned it for 3 years and it’s run a lot without the engine running. Also wondering about the fuel shutoff switch. The thread I found, which I’m having trouble linking, mentions it but I never knew I had one. Unfortunately the van is at work in the garage so I can’t run out and look right now. Will be up there later today.

So I guess I’m curious if there are further tests I can run on the ecm? I know I should check voltage at the pump but haven’t done that yet. I don’t have a fuel pressure meter but could maybe find one. Seems weird that they both go at the same time? Stranger things have happened I suppose.

thank you,
Dan

 

In case the novel I wrote up there wasn’t enough I thought I’d post an update for anyone reading who may be experiencing something similar. The ecm relay was very corroded like I said before. The female portion was corroded as well. First thing I checked after my earlier post was the inertia switch. It was difficult for me to get the wiring harness to come out. I eventually works it out and saw the plastic had been melted a bit. I cut the switch out and jumped the two wires together and vroom. Started. Fuel pump relay was very warm. I’m going to wire in a new female end for the ecm relay and that should calm the fuel pump relay down a little so it’s not working so hard. Trials and tribulations.

peace out

 

The frame pump has failed?
The test is to pull the frame pump and harness down and test the voltage to the pump
Behind the cover and foam, the wires used to break (often) where they attach to the pump
Good luck

 

Yea not getting voltage to the frame pump. Inertia switch is bypassed and I had it started last night. The pump has to be pulled out to test? after rewiring the ecm harness the frame pump won’t run again. I unhooked the two spade connectors on the pump and pulled them out a little and hooked my multimeter to them and got nothing on crank which is obvious I guess. Just looking for clarification on the behind the foam part. Thank you for taking the time to respond

 

Oh they break behind the foam, I think i understand what you’re saying. There are little rubber boots on the spade connectors but otherwise the wiring is pretty much out in the open. I think this pump was replaced before I got the van. I checked the fuses under the dash

 

Sounds like yours is a wiring issue
Yes the wires used to break the little spade connectors off under the little rubber boots
If you checked for voltage on the bigger outside the foam connector and have none, You need to trace the wiring back to the selector switch and the inertia switch / fuel pump relay

 

Thanks for the info. By selector switch you mean the front/rear tank switch? Thanks again. I’ve learned a lot from your posts in the past

 

A weak electrical connection or burnt copper wire will cause the pumps to draw more amperage which in turn will cause other weak connections to fail. Also a burnt wire and failing connection will raise the resistance and cause more heat and voltage drop. It would be to your advantage to check and clean all of the connectors involved with the fuel system. The HP pump could be going out and pulling more amperage then it should.

My ohm meter is in the shop being repaired or I would measure the resistance on my spare HP pump and let you know what it should be.

BTW if name brand batteries leak and damage a device, the battery company will repair, replace, or repay you for the device.

 

Yes. Tank selector switch. You may need the right schematic for your truck
Good luck

 

If the duel tank wiring is factory, then here is a diagram for a 1988 which should be the same as 1990 There were some changes in the harnesses on 1990 so the colors may be different, i am not sure.
From 1988 Ford EVTM

-
-
This pic is from the 1988 Ford service manual

 

Thank you annaleigh and manic. Much love. I went on a multimeter adventure and found the fuse link from the starter solenoid to the ecm relay did not respond to a continuity test. I’m about to replace that and the fuel pump fuse link with inline atc/ato 40 amp fuses. Will post results. I actually didn’t know about fuse links and was very confused about these 12 ga wires that diminish to an 18 ga or smaller wire for an inch or two. Silly engineering imo though I’m no automobile designer. Thanks again

 

Here is another diagram that is linked to the first one I posted that shows "fuse link M page 10"

Here is page 10. You can see that there are several fuse links that come off of the starter relay. Modern cars use power distribution boxes under the hood instead of so many fuse links. You can search junk yards and try to find a power distribution box you can use or do like this guy in the video and buy one. Then he cut out the fuse links and wired into the PDB. In his video he had a little different set up he called a "Duck Foot" where Ford uses the starter relay terminal.

Also i can't vouch for the seller but here is a 1990 Ford Econoline EVTM at a great price $15 and free shipping. These diagrams I have posted came from my 88 Ford EVTM and the book will serve you well!
https://www.ebay.com/itm/39428672068...Bk9SR4zyytKMYQ

 

So the whole time I was chasing an electrical problem the fuel pump relay was bad. It was new. I made the mistake of only testing the relay with power to hear the click and didn’t test the relay for resistance. So my issue now is that after a few minutes of running the fuel pump relay gets really hot and gets destroyed. A little bit of melted plastic making it difficult to remove the spent relay. I’m thinking it could maybe be a ground issue. Would a voltage drop create heat? Could this have something to do with the new rear in-tank fuel pump I installed?

 

A loose connection makes heat and melts the connector
There is big juice going thru the relay when the pump starts to fail
Get a new connector for the relay if needed to make it tight
<Make sure the wires are not hard as a rock.
That means more resistance and heat

 

Right on, thanks manic. I rewired the fp relay female connector. Wires feel soft and not overly hard. Thank you for those pointers. She fired up. Runs but intermittently wants to quit. Starts right back up after. Also, high pressure pump now runs with the key off. I did a real life face palm when I heard it lol. Fuel pump relay doesn’t seem like it’s getting hot anymore so you were right about the loose connections : )