1983 Ford F250 With 460. Duraspark ignition.

Symptoms: will start and run, but after 5 seconds (sometimes as long as 30 seconds) it will stall. No faulter, no stumble, seems as though the electrics have been shut down.

Attepts at fix: Replaced coil and ICM, no change.

Fuel delivery is constant, can't find any reason to blame this.

When it is running it runs as well as it ever has. Will rev and hold RPM's.

What else should I be looking at?

 

Just a hunch, but a worn ignition switch? Maybe after a while the switch contacts get hot from years of carbon build-up and switch "off" even though the key is turned "on".

The switches are about $20 at NAPA, and are on the steering column behind the dash (there's a rod that runs from the key barrel down the column to the switch). I would check that first (if it's an 83 and you've never replaced it, you'll need to soon anyway, so this is a good time to do it).

Oh...also check all your grounds on the motor and frame. I would disconnect, clean, and reconnect all of them you can find. Bad grounding is a real weak spot for our trucks as they age.

If that's not the issue, it's possible the Neutral safety switch went out. Mine did once (it wouldn't run at all though). The NSS is down on the transmission and runs about $35 or so. You can bypass it with some creative wiring to see if that's the problem before purchasing a new one...maybe try that first. Again, if it's a 22 year old truck, that switch will most likely need replacing soon anyway, so my advise would be to take the plunge, but it's your call.

One more thing...check *all* electrical connections you can under the hood and dash. Clean them with emery cloth or whatever you can, and squirt some dielectric compound into each connector to keep corrosion down. Most of these electrical gremlins can be traced to a poor connection of some kind...usually grounding.

Dan Martin
1986 F350 Crewcab Dually, 460, C6

 

Dan, thanks for the thoughts...Don't think anything could be getting hot...or even warm. It was a whopping 55 degrees here today and it will only run for 5-30 seconds. It will start with consistancy, but not stay running. After about 10 cycles the exhaust will start to warm up.

I've tried wiggling and jiggling the key, with no change, but may go ahead and swap out the ignition switch any way. I spent the last 2 hours pulling every plug in the engine bay apart and spraying them down with electrical contact cleaner, then re-greasing them...still no change.

I keep coming back to possibe ICM. I'm wondering if the new one I got is also bad...I'll take it and ask for a replacement tomorrow.

Neutral safety switch would not allow it to start at all, shouldn't even allow it to crank...

Anybody have more ideas?

 

Well, when my NSS went out, the engine would crank but would not catch. This was a while ago, but I think the NSS has two poles...one for the starter (Pink/blue wire I believe) and one for the ignition circuit (I think it's the same circuit that runs through the oil pressure switch and controls the fuel pumps). Anyways...I had changed out the ignition switch (my first guess) with no change in the behavior, but changing out the (very greasy and gross) NSS did the trick...she started right up.

Please do check your connections though...it's possible that either through vibration or corrosion, a connection is hovering just on the edge of some resistance level that will either allow or kill the ignition circuit. I would strongly suggest looking at all of your grounds first. If you have an ohm-meter, just check the resistance between each ground on the vehicle and the negative battery terminal...it should be a very low number.

Dan

 

How Are you checking your fuel pump(s)? When you start your truck, the power for the fuel pump(s) comes from a fusable link on the starter relay. When the truck starts, then the power travels through the inertia switch and then the fuel pump safety switch which is below the oil pressure sending unit. this safety switch needs 15 psi of oil pressure to keep the circuit open, this is why the first power supply comes from the start hot so the fuel pump(s) can operate until the oil psi is 15. You can place a jumper wire in the socket to complete the circuit to test this. Also check your fuel pump relays, I had the same problem with my 85' F250. If you need some electrical schematics, go to www.fordtruck.ddeboer.com

 

I believe that an 83 is still carbed so it doesn't have an electric fuel pump. It can be the pickup coil inside the distributor. You have changed the other two main culprits in the duraspark sustem. Next time you get a chance when it does this see if you have power to the icm form the ignition switch. It is the red wire going to the icm.if not then switch is problem.

 

I put in a glass filter near the carb. I can watch it and see that it stays mostly full. Hence my thought that it is not fuel delivery related. Thanks for the link to your schematics, will surely put them to good use.

Yes it is and it sure does... This truck is carbed but it has the dual tanks, fuel pump/sending unit in both tanks and an electric switch motor that (I think) does some pumping also...

Thanks for the ideas...It's gonna be the weekend before I can get back out there, so if anyone comes up with more thoughts...I'd like to hear them. I'll post up if I find anything new.

 

O.K. I'm back around to working on this. This morning I cleaned up every ground I could find, added a few to seperate body panels, ran them to a bolt welded to the frame, ran one from there to engine block (on driver side) to battery negative.

Also opened up every plug and connection I could find. Sprayed it down with contact cleaner and re greased.

There is no change...

In watching the fuel flow through the glass filter, it seems that it will slacken off a bit after a few seconds of running...so I'm starting to think of DeBoer's idea:

Tell me more about this "jumper" jump what? and what socket? Do you mean from pin to pin on the wiring harness side of the plug that attaches to the saftey switch? It's a three pin connector with two wires leading to it...which holes?

What should I expect it to do...is this just fooling the system into thinking I've got 15psi of oil pressure? If that is the case then it would mean that I'm not getting 15psi to the saftey switch...Is this likely a switch malfunction or a oil pump problem?

 

I think I figured out the "jumper".

Put a wire from contact to contact and can hear a relay over near the ICM clicking. Start it up and it still stalls. Got my wife out to turn the key on and off. I can NOT hear the fuel pumps going...but get power to the plug on the front tank (can't get to the rear plug). I've killed the battery again with all the cranking...will have to let the charger work for a while.

Any body else have any good ideas?

 

Check the small wire from the fuel pump safety switch after you reconnect it and see if you have power once the engine starts. The jumper I talked about was to bypass the switch. If you have power to one side of the switch and not the other after the engine starts, you either have no oil pressure or a bad switch. If the switch has power to both sides after the engine starts, you have a bad fuel pump relay. There are 2 and they are green(Or mine are). What you then need to do is get to your fuel tank electrical plugs and check for the proper voltage at the right wires. Go to www.fordtruck.ddeboer.com and find the fuel pump schematics. You can go there and find the engine schematic and check the power connections also. I will try to find the schematic for the fuel pump relay and post it on my site. I also have a good fuel pump troubleshooter article also. Let me know if you need it.

 

??????? Can't find a Fuel pump saftey switch in any of your schematics or in the haynes book.

Do you mean the Inertia saftey switch? I've checked it. Pulled up on it, and reset it...no change.

 

Or did you mean the oil pressure safety?

"little wire" my oil pressure safety has 2 wires, both are red, both have a secondary color, may be the same or one is yellow the other is tan...They are the same size.

 

Start at section 4-7 thru 4-12 in your haynes manual #36058 ford puckups and bronco 1980-1996. Then check section 12-7 to check your fuel pump relays if so equiped. Then go to 12-23 and 12-24 for your chassis electrical and study chapter's 4 and 5. Check this diagram http://www.ddeboer.com/fordtruck/pag...0Tanks_gif.htm
and this
http://www.ddeboer.com/fordtruck/pag...meter2_gif.htm
Pay close attention to circuit #640 and fuseale link #37 at the starter relay, which starts out blue and turns yellow after the fuseable link.

 

Now we are getting somewhere...Pulled one of the relays near the ECM. Figured them to be the fuel tank shut off relay or the fuel switch relay...we were able to match one of them up at my local Carquest. The one I have is a 5 pin relay. There are 2 of these then a 4 pin relay all in the same area. Don't know what the third one is for...my wires are so covered up in gunk I can't see what color they are...CQ only had one of the 5 pin relay so I brought it home and plugged it into one of the plugs...same ol'e symptoms...swapped the new one into the other socket...ba-da-boom ba-da-bing...It ran, and stayed running.

In CQ's computor and several of their books, we could only find one relay..."fuel pump" was all that was listed...could not find a "fuel pump cut off" or "Fuel selector".

Here is what I need help with:
What are the 3 sockets for? (2 five pin, 1 four pin)

Anybody have a part # (for any of the AP stores) for these relays?

Are the 2 five pin relays, that look the same, actually the same? or does one have a different resistance?

D. DeBoer, Thank you for the schematics they have been incredibly helpfull, not just on this problem. You might think about changing the graphic on your front page though...the big banner that says "FTE users click here" or something like that...It has some script in it that I was unable to see using my version of Linux and I could not find a plug in to match...so I booted up my old version of windows...and it couldn't read it either...so neither OS would let me click on the link...my wifes copy of XP handled it just fine and I was able to get past the gate...and email myself the individual pages.