Subtopic	Posts		Updated
	New fuel PUMP not tank. idiot (me)	1		05/17 07:25pm
	The dealership replaced the fuel tank, now it's fine....hopefully NM	1		05/15 12:07pm

By Andrew on Thursday, May 10, 2001 - 12:31 pm: Edit

This morning I was on the freeway and my disco acted like someone had cut the fuel line. After pulling into the emergency lane, I noticed that she idled just fine. But, when I applied gas- it sputtered pretty bad\wouldn't accelerate. I got it to a gas station thinking, maybe I got bad gas. But before I filled it up I started it up again, and it ran fine, so I drove it into work. It didn't *fully* act up again, but it seems the power is a bit limited. I'm taking it to the dealership, but I'd like some input before I go in...seeing as it's not my normal dealership ( i'm out of town )

Any help besides the obvious ? (fuel pump, just had a fuel FILTER replaced)

Andrew Nix
'96 Disco

By Parker on Thursday, May 10, 2001 - 12:48 pm: Edit

Go here...


http://www.discoweb.org/discus/messages/9/1138.html?989441876

By Jon on Thursday, May 10, 2001 - 01:05 pm: Edit

It's highly unlikely, but it sounds like one of the characteristics of an engine that's jumped time. I had a car do it once; ran fine, idled smoothly, but bogged and acted like it had no fuel when you pressed the accelerator very much. The dealer couldn't belive it (misdiagnosed it the first 2 times) because he said the particular engine wasn't a "free-running" enigne. Rover V8s are supposedly not free-running, but my car's engine was able to jump time and it didn't damage it, so it could've happened to you. The cause of my problem was plastic coating on the timing gear teeth that had stripped away and allowed the timing to retard several degrees under acceleration, but corrected the timing at idle and cruising. I don't think Rover uses plastic-coated timing gears, though.

By Andrew on Thursday, May 10, 2001 - 01:34 pm: Edit

It's not a sticky valve. AND the check engine light is NOT on....It's like the fuel pump is cutting power to the engine. It seems like someone mentioned a road speed sensor doing this....ring any bells ?

By God on Thursday, May 10, 2001 - 02:22 pm: Edit

Speed sensor.... ~$70 left side of transfer case.

By Andrew on Thursday, May 10, 2001 - 02:29 pm: Edit

Thanks for the price god, but I was looking for an experience that might compliment mine.

Andrew

By Tom on Thursday, May 10, 2001 - 02:43 pm: Edit

Andrew,

I had the EXACT same problem, and ended up replacing nothing. I think this can happen if you don't have your gas cap on nice and tight. For some discos (97's, i beleive) there was a recall that fenagled with a ring around the filler neck to ensure a tight fit.

The dealer diagnosed a new fuel pump, which does cause the same problems, but it has been a year and i haven't replaced it or had the problem again.

Tom

By mrbieler on Thursday, May 10, 2001 - 02:50 pm: Edit

Fuel tank vent issues can cause the symptoms you experienced. You say you had to fill up when this was happening. It's not uncommon when you run the tank down.

Did the gas cap hiss when you popped it? If that is the issue, you'll need to track down in the system where the vacuum leak is occuring.

Just one more thing to look into.

By Jon on Thursday, May 10, 2001 - 02:57 pm: Edit

What's that mean? I thought there was supposed to be a little hiss (if any) when you unscrew the gas cap. Why would a vacuum leak cause pressure to build in the gas tank? Maybe I've got it all wrong...

By Blue Gill (Bluegill) on Thursday, May 10, 2001 - 03:03 pm: Edit

pressure builds up within tank as vapor concentrations increase (as liquid fuel is used, there is more room for vapors to accumulate). When your tank is really really empty, you have over 20 gallons of vapor space. Heat and vibrations will also add to the pressure. All tanks his when you pop cap (pressure being release outwards). I'm not aware of any potential vacuum line leak that could pressurize (negative or positive?) the fuel tank...is mrbieler talking about a hiss inward (vacuum) or outward (pos pressure)?

By Kyle Van Tassel (Kyle) on Thursday, May 10, 2001 - 03:06 pm: Edit

Hmmm , sounds allot lke a MAF. I am voting for either that or its starving for gas..

Kyle

By Blue Gill (Bluegill) on Thursday, May 10, 2001 - 03:08 pm: Edit

OK, I'll bite...what's MAF?

By Ron on Thursday, May 10, 2001 - 03:11 pm: Edit

Mass Airflow sensor.

I think. have not had it break yet so i don't know. Does it do the same thing when you rev in neutral or only when driving?

Ron

By Kyle Van Tassel (Kyle) on Thursday, May 10, 2001 - 03:15 pm: Edit

Typical MAF symptom is that it will half ass idle then die just off idle. If the intake hose come off part way between the MAF and the engine shit like that will happen as well..

Kyle

By Ron on Thursday, May 10, 2001 - 03:17 pm: Edit

"half ass idle"

Is that the technical term for it, Kyle.

Ron

By mrbieler on Thursday, May 10, 2001 - 03:20 pm: Edit

The system is supposed to vent. If it's not venting and getting air into the system, it can cause fuel starvation and/or damange the fuel pump.
The tank has a vacuum relief system. The hiss you get when you pop the cap is from the vacuum created. That's part of the reason you see the warning "turn 3 clicks" or whatever the print is, on your cap.

Someone recently described it like burping a baby which I liked. I you don't burp the truck properly, it will spit and vomit all over you. ;-)

Jeff

By mrbieler on Thursday, May 10, 2001 - 03:20 pm: Edit

The system is supposed to vent. If it's not venting and getting air into the system, it can cause fuel starvation and/or damange the fuel pump.
The tank has a vacuum relief system. The hiss you get when you pop the cap is from the vacuum created. That's part of the reason you see the warning "turn 3 clicks" or whatever the print is, on your cap.

Someone recently described it like burping a baby which I liked. I you don't burp the truck properly, it will spit and vomit all over you. ;-)

Jeff

By Kyle Van Tassel (Kyle) on Thursday, May 10, 2001 - 04:06 pm: Edit

WHy yes Ron , that would be my technical term for it....

Kyle

By Blue Gill (Bluegill) on Thursday, May 10, 2001 - 04:09 pm: Edit

so hiss we hear is inward airflow from vacuum, and not outward pressure blow-off? I never get my nose down there to really check - all those nasty carcinogens and all...

By Andrew on Thursday, May 10, 2001 - 05:55 pm: Edit

Thanks guys. LR Portland is looking into the "issue"- hopefully it'll be good to go when they pick me up on monday. i'll be working on it myself after the warranty runs out, but I'd rather know why it's doing what's it's doing than just "take it to the dealer". They didn't have any loaners so I got a full size Chevy Astroglide Van. Oh humm...already miss my disco, chevy's are shit, now i know why i don't like anything else!!

By Milan on Friday, May 11, 2001 - 12:31 pm: Edit

Inward air flow on the tank? I always thought that it was pressure building up in the tank. The label on the Disco gas cap says to turn it quarte/half a turn to prevent fuel spillage. That would mean the pressure is pushing the fuel out. If you had vacuum going, you would not be able to open the cap.

Just my 2 cents.

By HeeHee on Tuesday, May 15, 2001 - 01:08 pm: Edit

One way to avoid the problem of hissing is to do what I do. Have your wife leave the gas cap at the gas station every two months or so, until you give up and just run the truck with no gas cap. No hissing problem ever! Not recommended for off-road use, at which time you can stuff a rag into the gas-hole.