To start off, I lurk here often, since I seem to always be fixing something on the Disco - the Search feature gets a lot of use by me - and I very much appreciate all of the time you good folks put into helping others. That being said, I wanted to share my fuel pump fun time these past few days, in the hopes that it will benefit others. Mine is a 1997 Discovery I, 128k, automatic, non-AEL, daily driver that I've had for about 2.5 years now. I'm not remarkably mechanical, but I'm learning a little more each week w/ my beloved Disco. Thus far, I've replaced window regulators, lock mechanisms, radiator, most of high mileage list on here, front and rear seats out of 1999 DI at the salvage yard, brake pads/rotors/bearings, and probably some other stuff I'm forgetting. And I need to do the rotoflex pretty soon.

This past Sunday, I was quite a ways from home in the mountains (of course), when the dreaded cranks-but-won't-start happened. I had been out hiking for several hours, car ran fine in the morning, then nothing when I got back. I started with the fuse under the hood, and the 15A (I'll come back to that) in F6 was intact. Back in the car, turned the key between PII and PIII, and could hear relays clicking in the passenger footwell, but no hum from the rear of the car. First guess, fuel pump is toast. Unscrewed the fuel pressure cover and pushed the Schrader valve, gas dribbled out but didn't push much...not good. Pulled the carpet up and took the cover off of the fuel pump access (I keep a basic tool kit in the car, for times such as these). Screws were rusty but not terrible. Cover off, and lo and behold, the pump had been changed back in 2008 (or at least that's my guess based on the sticker that was on the top). Unfortunately, I don't keep a multimeter w/ me in the car (probably will now), so physical inspection of connector was about all I could do, and it looked OK.

I was not optimistic at this point. I decided to walk a bit, think about anything else I could do with what I had and where I was, before resorting to calling for a tow. Upon returning back, I figured I'd try again one more time, and...relay click, fuel pump buzz, car starts. Um, OK. Headed home, counting my blessings and planning to stop to pick up a replacement pump at Autozone on the way home. The Airtek was in stock, plus a new filter, the Disco started again after leaving the store (was worried about that one), and I made it home to swap the pump.

Pump swap was smooth (except for the fact that I had just filled up the day before), filter not so much. PB'ed those bolts to death but could only get one to budge, so left it and hooked everything back up to test.

Nothing. No pump buzz, no start, nothing. Hmm...

It's getting dark at this point, so I headed in to the Interweb to try and find the next troubleshooting path, resigned to having to drive the motorcycle to work in the AM (which I normally wouldn't mind, but a 20-mile commute in 40 F temps was not appealing).

Monday morning, out of curiosity, I tried to start...and success! Pump buzz, fuel pressure builds, Disco starts right up. Um, OK. Guess the pump needed to soak awhile (not really, but nothing else made sense). No problem in to the office. End of the day comes, ready to head home, and...nothing. No buzz, no start, nothing. Crap. Troubleshooting in the office parking lot is fun. Gotta be intermittent electrical problem, right? Looked up the wiring in RAVE, which didn't seem to matter since the multimeter was still sitting on the workbench (my stupid fault). So, AAA ride home, a little poking in the dark in front of the house to check the rear ground locations in the RH and LH pillars (E400 and E401 in RAVE) and resigned once again to motorcycle ride in the cold.

This morning, motorcycle ride in the cold wasn't as bad as expected, ride home was even better (sunny and 70s!). Back to the Disco, determined to fix at this point. Started with a bench test of the old pump - pump works (shoulda done that before buying the Airtek, but I don't mind having a spare now). Bench test of the new pump (just because) - pump works. Gotta be electric. Fuel gauge works, meter says no volts at the pump, white/purple wire. Moved back to the connector under the driver side rear wheel well, no volts at the white/purple wire. OK, to the relay...and here's where it gets weird. RAVE says K119 behind the RH trim by the feet...where I have no relay with the white/purple wire, and none that are blue like in other photos. Interweb says there's a relay under the hood RH side in front of the washer fluid tank...but on 1999+ and not on 1997? Um, OK. Sure enough, I have the relay under the hood, there's the white/purple wire. Power at the fuse, no power at the relay, and none at the inertia switch (which wasn't tripped...I tried that on Sunday). Ground wire next to the relay looks REALLY dirty. Cleaned up, retightened, cleaned the connector next to the inertia switch (white/purple wire there too) and replaced the 15A fuse with a 5A, since that's what the owners manual says should be in there. Voila, pump fires up, car starts, test drive...and it dies. 5A fuse blows. Replace the 5A with a 15A, and all is fine now.

So, to sum up for others...fuel pump relay location may not be where RAVE says, but the rest of the circuit map seems right. Keep a multimeter or check light hand. Bench test your old pump before buying a new one (again though, not unhappy to have a spare). Check your grounds, especially the one right next to the engine bay relay. Don't know what the deal is with the 15A fuse in F6 - anybody got any guesses? And any concerns over running the 15A instead of the 5A? Also, it now sounds like I've got lifter tick? It's been cold at the house at night, so that may be unrelated and just the first I've noticed it this season. Probably not the most methodical of troubleshoots, but it's done and back on the road and I don't have to freeze in the morning again.

Thanks ya'll for all your help with other peoples' fuel pump problems, it certainly helped me figure out mine.

 

K119 would indicate you were reviewing the multi-port fuel injection, while the NAS spec units are a few pages further on as Sequential Multi-port fuel injection (SFI-V8 NAS only). But the MFI injection diagram shows 15 amp as well as F6.

F6 on page 41 of 591 in the RAVE electrical guide for the 97 shows to be 15 amps to start with. I have measured the pump draw of my 97, and it is right near 5 amps, so I am not surprised that you had problems with fuse. I also looked at the owner manual, it does say 5 amps, and a second place in the RAVE electrical guide shows 15 amp. Based on my 5 amp readings (170K miles, unknown if pump is oem), your troubles, and two drawings, I'd stay with 15 amp. The owner manual was most likely composed and reviewed by marketting weasels, not engineers or technocrats. Could have been a typo, I've bin knowed to mizspell and hit da wrung keeezz.

IMHO all owners would do well to inspect that fuse and change if needed.

 

In my hasty review of the electrical circuits in RAVE, I obviously missed that F6 is 15A there vs. 5A in the owner's manual (OM is much easier to peruse) - thanks for that, SB. I feel a little more secure now. I would concur, probably worth checking that F6 to see if you're running a 5A (in the event some PO or mechanic replaced it based on the OM) or 15A (stock condition? or somebody replaced it based on RAVE?). I'll check this evening to see what the new Airtek pump is actually drawing, but given that the 5A blew pretty quickly, I'd guess it's at or over.

Quick update on the fuel filter, I forgot to mention that. I could get one of the two sides loose, so I went back to Autozone and exchanged the fuel filter with threads on both sides for one that is threaded on one side and b-a-r-b-e-d on the other. Just going to cut the stuck (and now rounded) side off and hose-clamp it. Fortunately, the flow direction is correct!