ZR1991

My LT5 has been near perfect for the time I have had it, except for a chip problem resulting in a high idle.

Now somethig has just started.... The engine starts normally, hot or cold. After a few minutes running, regardless of speed, it suddenly dies... just like fuel running out. Try to start immediatly, no dice. Wait 10 min, and it starts and runs fine. Then without warning, kills again. Replaced fuel filter, gas appeared clean, but once restarted, car ran fine for 5 minutes, and then killed. waited 10 minutes, restarted, fan fine long enough to get it back into parking place.

Basically, I would describe it as running out of fuel. But why would it wait 10 minutes, then run fine for 5, then kill again? Has me stumped.

I would like to fix this myself for budget reasons, but if I can't do it by tuesday it goes to the dealer. I'm off tomorrow (Monday). Anyone have any hints?

PS.... Guages look normel, including "check engine soon" light

It almost acts like an obstruction that lets fuel by slowley during the 10 minute wait, then can't allow enough to let it keep running. But it runs very well when it is running, and the stall seems the same whether at extended idle, or 3000 rpm.

Any LT5 fuel gurus out there? PS again, when I was working on the high idle problem, I learned all about the IAC, TPIS, etc, and the "spider" of vacuum hoses under the plenum. I sort of want to rule them out because 1) the symptom does not relate to engine speed, and 2) the "spider" was thoroughly checked and sealed when the plenum was off 3 months ago.

Thanks in advance,

Art "Dizzy in Baton Rouge"

Rush, Please, any help gratefully accepted, no matter how weird!

PS#3... Can the tank be drained? Has about 5 gallons it it... put in by my wife last Saturday when she brought the car to a cruise in (I drove the Cobra). This is something she has never done before, but she thoroughly enjoyed it, and now she is sure it's her fault. So now you see this has some political and future cruising fun implications as well... HELP!!!!


[Modified by ZR1991, 9:29 PM 9/2/2001]

USAZR1

Just a guess but it sounds like your primary fuel pump has failed,Art. You might check out the troubleshooting procedure in the shop manual.

ZR1991

Arrrrrgh....


The same conclusion I came to overnite. Why couldn't it be something simple like the end of the world? I thinl I'll look at the circuit breakers first, but i think it's the pump.

Keep you posted.

GTB/ZR-1

Art,
I think Clint might be right, but it sounds a bit like vapor lock as well--good luck...

ZR1991

Assuming it is the fuel pump, which (upon reading the fuel delivery part of the book) it does appear to be, am I right that the pump is not seperately replacable, as the book says. It says that you need to replace the entire "fuel level metering assy" for either pump, or eithe in tank filter.

The reason I do think now that it is the pump is that the book says the second pump operates only in cold starting... AND COLD OPERATION.... and when the ECU tells it to go to full power (after warmup). So if my first pump is bad, I would have the symptom I have, which is that the second one would run the engine thru "warm up", then shut off, killing the engine. In addition, I just started the engine and removed the FP1 fuse, and the engine continued to run, indicationg, at least I think, that the fuel was not comming from the first pump. The fuse FP2 for the second pump is too hard to get to at this time, but that would absolutely confirm it if the engine killed on its removal.

Does this make sense?

Thanks, as always, Clint, and to GTB as well.

USAZR1

You can replace either pump separately,Art. If you buy the fuel pumps from GM,be prepared to sit down before you're told the price,,around $500+apiece. Some of our Registry members have found some other pumps that are practically identical and cost around $50+apiece. Go to our website and email our Oregon State Director. Scott is a do-it-yourself wizard that has done this repair before and can give you the info needed to do it,cheaply.

ZR1991

Clint,

Thanks again. In fact, I just got an on line price, and fortunately, I was sitting down!

My medical bills are such that I was going to start posting about storing the car (that's why I briefly considered selling it a few months ago, but it is too much of a morale booster, and dammit, I love the car!).

I will take my time, and contact the fellow you mentioned, and continue to post here. I appreciate the help, as always. Especially sporting to a no Registry member. But You know I will sign up when I can.

BTW, one thing I will do is pull down the right kick panel, and pull the #2 fuse while it's running. If it kills, I cnsider that to be conclusive. Do you agree?

Tyler Townsley

Car Quest part # E3904 ~ $65 ea. 30 Min job max.

Tyler
90ZR1

USAZR1

Thanks for the help,Tyler. What application does that part number cover?

Tyler Townsley

This is the ZR 1 pump. The number comes from some old zr 1 net posts that I chased down some months ago when mine failed. You can use the lt 4 pumps but I opted for the 3904's. They had one in stock in Fla and had to go to a central whs to get the second one so it's not a high volume item. The lt 4 one is cheaper and has been used by some as a sub but this has a higher flow rate and is not made by carter.

Tyler
90ZR1

USAZR1

My personal archives show a Borg Warner(BWD)P36 fuel pump that is an exact replacement,plugging right into the harness.
Fuel tank gasket: #25091503 dealer item
Fuel strainers: #25055455 & AC Delco number TS-1 dealer items

Another pump that is supposed to fit and work fine is the AC Delco #EP375
This is the one I would check out,first.

ZR1991

Thanks,

Does it come with the wiring harness?

Since I haven't opened mine yet, I assume the pump has the harness molded to it in some fashion.

This has been a lot of help. Of course, no one is open today in our area. Go figure.

Regards,

ZR1991

Well, this thread can end on a good note.

Here is a e mail from the fellow that Clint recommended, Scott, in Oregon:

Clint is right. This pump can be replaced fairly cheaply. Go to NAPA
and ask for the Carter part # P74037 that is the latest and greatest
part that works that I know of. There are two version of this part number.
One has the Carter name on it. The other does not.
The symptom you describe is very likely
the primary fuel pump. Once you get the assembly out look to the manual
page to see which one is which. AND loot to this page for some pictures on
how to replace it. http://www.zr1.net/ZR1_howto.html
The Primary pump is not the lower pump like you would
think.
Be careful around fuel. It takes about an hour to replace the pump if
you have done it before. In not then give yourself 2-3 hrs.
Scott
90 ZR1 #64
(s-f10)


Because I knew NAPA was the only store open today, I went there, and got the exact part he described. Instructions in the manual and with the part wewe crap, but I took my time and just took it apart and put it back like it was, and it works. As described by other posters, this particular pert is a direct replacement, and has the correct electrical connectors, so there was no jury rig. Cost.... about $65.

Just came back from an hour drive in the rain, and the car was super. I know how easy it is to imagine other improvements when something like this happens, but I did think I noticed something. I won't drive the car til this comming weekend, and I'll know then. So I'll reserve judgement and just say it worked.

Thanks to all, ant the other part numbers described would work also, I would imagine. The only issue is to be sure you get the right electrical plug if possible. That site that Scott mentioned has an excellent picture of both the right and the wrong connector, so if this ever happens to you, you might look at that site and print that picture, so when at the parts store, you won't have to guess (I am assuming that you, like me, would NOT open the tank first, so you would not know what the pump looks like).

Oh yea, one more thing.... Scott was also right that the pump #1 is the upper one, not the lower, as you would think.

The forum saved me on this one, because the service manual just skips over this repair, claiming it can't be done. I can see why, it is complex, but very, very doable, and if you do it the book way, the entire assembly is $600-700, priced today, as opposed to the pump cost of $65.

Regards, and thenks to all. BTW, if I notice the performance issue I alluded to earlier, I'll post this weekend. Might give some others something to think about.... could be that the pump had been affecting me for quite a while.

USAZR1

Just think,Art,,you saved enough to more than pay for a LT5 Registry membership. :D Glad to hear your car is purring like a kitten again.

ZR1991

Dammit, Clint, you know you're right. Be talking to ya soon.

This is a perfect example of the value and life of the ZR1 being enhanced and extended just because of the dedication of the group of great people who own this car.

Boy I am soooo glad I did not sell mine earlier. Actually had it done, but the guy got wiped out in the floods here in the south in the spring, then the market crashed and the price was too high. Guess everything happens for a reason.

Might even take it to work today. Yep.

Regards,