89Reatta

I replaced the fuel pump on Thursday. I have driven it from 3/4 tank down to below 1/4 since then and there are no problems. This would have been impossible before the fix. I did all of the work myself. The fuel filter cost about $20, the fuel pump resistor was around $65, the relay around $90, and the fuel pump around $50, so the grand total was around $225 and I know everything is new now. This problem is fixed and should last for the rest of the car's life. The billable shop hours for all of this is around 4.5 hours so if you bring it to a shop, expect to pay from $360-$540 for labor for all of this work. I would recommend doing it yourself though; especially the under the hood stuff, it's really simple. Actual time to DIY is about 2.5-3 hours. The fuel filter was the worst, in my opinion. The fuel just keeps pouring out, no way to really stop it until you're done. The fuel pump is pretty easy to replace; the hardest part is dealing with all the spring-loaded hose clamps. Be careful not to drop any down into the fuel tank, I could totally see that happening to some poor soul. My '91 LS400 has 300k miles and going strong I live in southern California, and the temps have been in the '70s and '80s for the last several days.

Timinator

Thanks for the fuel pump fix. I will try that.

My '92 did it last night again; it was 70 degrees out, windows down, no AC on, 1/3 tank of gas. I was in a rual area and stopped quickly with it sputtering and had my son go unscrew the gas cap. Lot's of pressure was released, the idle went from 700 rpm to about 1100 momentarily, then back down, but the problem with the sputtering wasn't fixed after putting the cap back on and trying to drive away. I put the car in neutral and let the car coast, turned it off, then back on and the sputtering went away. I will replace the fuel pump.

91ls400own

Had same proiblem on 91, then started surging. Tried several things until I changed fuel pump - Now runs great!!

Garage7RP

iTrader: (1)

I think the fuel pump resistor would fix this problem unless you know for sure that your fuel pump is really bad. It is also a good call to change the fuel filter if it has not been changed all this time. Check the specs of the fuel pump resistor...

darimura

89reatta,

the fuel pump is in the tank?

89Reatta

Yes, the fuel pump is in the tank, but you don't have to drop the tank or drain the fuel to get it out. At least I didn't, I just ran it down to about 1/4 tank before I did the repair. Maybe it would get messy if the tank was 100% full. There is an access port to the fuel pump behind the back seat, you just have to remove the rear seat and there it is. It's pretty self-explanatory after that, the cover to the port just pulls right off, beneath it there is another plate with screws in it. You can pretty much just go for it, just don't smoke while you're doing it and be careful with the hoses and clamps and you'll be fine.

89Reatta

While the resistor is somewhat easier to replace, in my experience the fuel pump was actually cheaper than the resistor, so there really is no reason to try one before the other. I would actually recommend to just replace everything- filter, resistor, relay, pump- then you know you have a fuel delivery system that will last another 200k or whatever. It's not that expensive compared to the peace of mind you will get in return.

Garage7RP

iTrader: (1)

I agree with you.

488civ10

It's been hot in socal the past few days. Ran the fuel tank down to about 35-40% and the car sputtered again. As long as I keep the fuel flowing, it was fine to get to the gas station. Filled it up and went on my way.

So I can confirm now that the fuel pump resistor was not the fix, at least for my car. Will look toward replacing the fuel pump when I can get around to it.

KA8

iTrader: (1)

I have the exact problem... Power loss when warm or hot rarely any problem when cold outside. I thought it was an electrical issue but I guess not. I will get a new fuel pump soon.

KA8

iTrader: (1)

I have the exact problem... Power loss when low uel and warm or hot rarely any problem when cold outside. I thought it was an electrical issue but I guess not. I will get a new fuel pump soon. So can I get one from autozone?

89Reatta

Sure you can, I love Autozone. But if it's not incredibly urgent, you might as well go to RockAuto and get the cheaper one. You can have it at your door in less than a week. The Airtex pump that Autozone carries is like $170, you could get an OEM Denso pump for less than $100 at RockAuto. I just got the cheapest one for under $50 and it works perfect, same warranty as Denso, strainer included.

Loo-10-ant

Just an update on my issues...Like most on here troubleshooting all the suspicious and typical things to make our cars lose power and spending a ton of money for inadequate
results easter-egging parts, I think the Engine Coolant Temperature sensor should be considered the 1st thing in pretty much all cases to change before anything else. Sort of like CONDOM use!!!! ha ha.. It can save alot of time and money by changeing the ECT 1st. Many of us have bought used LS's that are 17-18 years old...and who know if ANY of the sensors have ever been changed or Modded by someone else just to fool the ECU for temporary fixes....The sensors on our engines are the "Soldiers" in the field that provide feedback to the ECU module that tells the engine what to do next... In my opinion "No start" conditions point to hard failures like Open, Shorted, disconnected, or Failed components... Poor performance can be sensor related, or marginally worn parts that do not operate to "Newer" standards in most cases. Therefore I think this subject should be "STICKIED", Change your ECT 1st!! THEN.....if that didn't fix your problem, the next few hardware changes may in fact works as you progress through your part(s) changing/replacing. Many of us as in my case wind up with a totally REBUILD External engine with new plugs, Fuel pump, Dizzy caps, rotors, wires, TPS, Throttle body cleaning, vacuum hoses etc.. and still wind up with poor performance, UNTIL....That pesky ECT sensor was changed and presto!! Now your car runs like it never has since you owned it!!!! Welllllllllll just think, you spent all that money on everything else and basically have a new engine "Externally"! Then the ECT Sensor was the Magic Bullet that killed the Noid!
-On the Flip side of things,
By Changing the ECT Sesnsor and fixing the problem, many of us would just stop there and not touch the other things...so my suggestion there would be to do the maintenance just as you normally would with the other parts. After all, on a 93, almost 18 years old, How long do you expect a Fuel pump to last????.. HOw much fuel has been run thru the lines?? Seafoam it! Buy a new one and have it around so when the present pump fails, youre good! This is just my suggestion to save many who come here some time and $$$$ in troubleshooting since we more experienced have been there done that...Like ECU Module repair....before they repair them, they usually change EVERY capacitor on the PCB before even starting the troubleshooting process of semiconductor troubleshooting I was told from a place who repairs industrial controls and manufacturing equipment. Just my 2cents...

Loo-10-ant, aka
-=Bruno Molly=- at LOC

J Ritt

Hi Guys,
I've been driving my car all winter and haven't had any problems whatsoever with the surging/idle issues. Now that the weather is heating up, I'm getting scared!

Has anybody else tried swapping out their fuel pump, resulting in a complete fix of these problems? I'm thinking about trying it before it gets too hot outside. Thanks!

tonyfazt

ok first go check for spark maybe you need to change the wires take out a spark plug and wire and turn on the car if no spark thats your problem
do that one by one