1997 NAS Troubleshooting Help

uc4me

Well-known member
yes, I was running low on fuel the night it was running crappy so I used fuel form a jerry can I carry with me and at the last moment I treated with some basic enzyme treatment for all fuel systems. The next day, it'd only turn over (no pump cycling sound)

I'll attempt to drop the tank within the next week and report back even though the fuel pump has only appx. 2500mi on it.

My hunch is its the C-113 connector that has shown to have a pin burn in past on other NAS trucks from what I've read.
 

BarryO

Well-known member

chuckc4

Well-known member
I had a fuel pump “burn out” once right after running low on fuel too. I wonder if the pump gets overheated if it is not fully submerged in fuel.

Seems plausible, but that limits the range of a 90 even further....
 

uc4me

Well-known member
That self-fusing silicone tape is great. Makes a water-resistant seal, yet can be peeled off when needed. Great stuff for protecting connectors exposed to the elements.

Just bought a couple rolls..I've used the Scotch Super 88 vinly tape in the past. (Thanks for the link UD) .

I had a fuel pump “burn out” once right after running low on fuel too. I wonder if the pump gets overheated if it is not fully submerged in fuel...

Well now that you mention it, that might lend reason.. I stopped when I saw it was low on gas but maybe a little too late.

I bet with my waving fuel gauge issue it was bone dry well before I knew it and might have been the reason of engine stumbling/hi-idle before the pump went in the first place..we'll see.
 
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uc4me

Well-known member
So figure this one...we planned to push the truck into another bay today so I could drop the tank and just before, I thought I'd turn it over. It fired right up. Several subsequent attempts resulted the same.. pump cycled, fired right up. Still not sure if related to that 4hr soaking drive.

I also noticed when I rocked the truck I didn't see the fuel gauge waver with the tank slosh as before albeit its only quarter full. Would a lose sender connection at pump or at gauge have this affect? I'm gonna pull that instrument cluster regardless and have a look and still may drop the tank to check that c113 connector. Kinda at a loss at this point.

Anyone wanna take a stab at this one?
 

chuckc4

Well-known member
Possible corrosion/loose electrical connection where the wiring connects at the top of the fuel pump (Not sure if that is the c-113 connector you referenc). The electrical connection is all at the top of the tank on a 1997. Dropping the tank is a pain but probably a necessity at this point.

As has been suggested, an empty tank makes this way easier — it is still a total pain in the ass job though...
 

Uncle Douglas

Well-known member
Callsign: delete
We have found lots of burned power pins on the tank top connectors on D1's. Those have a similar plug to the NAS 90. If thats the issue it will be obvious with the white plastic plug turned brown around the pin. The sending unit for gauge and pump motor share a ground. If both are acting up I would pursue that ground.
 

Steve 110

Member
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Whatever you do do this so the next time its 4 screws and pull the pump!
 

BMGmotors

New member
Very interesting as I believe I have had the exact same issues. Not sure if you’ve happened upon my posts at https://www.defendersource.com/thre...nt-start-no-fuel-pressure.128817/page-2#post-
I've been through 3 pumps in ten years. I‘ve also had a ordeal replacing the econoseal connector. The start of my problems also began after heavy rain. If I had replaced the connector first time around with the correct mark one, econoseal connector with all the proper rubber or silicone gaskets perhaps I wouldn’t have had to replace as many of fuel pumps.
 
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