Time

I didnt want to highjack someone elses thread so .........

I found out I put in the wrong fuel pump in my 91 Z28 (350TPI)

I took the entire sending unit with fuel pump from an RS and put it in my Z.
Mine was not working at all and I found the whole thing in a boneyard for $25

The car was not running due to bad gas from sitting for 2 years so I needed to get it running to see what the prob was with it.
The pump was not working anymore and I changed the fuel filter. Instead of removing the gas tank I ran a wire direct to the fuel pump terminal and let it pump out fuel until it quit pumping. I disconnected at the filter to let the gas flow out. My question is...did this get all the old fuel out? will the fuel pump itself pump out all the gas?
Next question...is this the wrong fuel pump for a Z28?

It cranked up but ran badly. I dont know if it is from an existing problem, some bad gas thats still in there, wrong pump or something else. Or a combination.

Vader

If the RS was equipped with a TBI system, the pump is likely straining to produce even enough pressure to barely run the TPI. The only way to be certain would be to test fuel pressure, so this is all a presumption. The design pressure for a TBI system is 11-13 PSIG, whereas a TPI should be able to produce 44 PSIG easily. The TBI pump can produce more than 13 pounds of pressure, but just how much is in question. I dount that it is close enough to the 37PSIG minimum to run the TPI.

FWIW, a new TPI pump can be had for about $99, with a warranty. As for the fuel tank, there may be up to two gallons of residual fuel in the tank after the pump has pushed all it can through the filter. It shouldn't add enough mass to affect removing the tank, which you have apparently already done. You'll stll have to use all the usual precautions for working around liquid and vaporized fuel.

Time

Well, I did not remove the tank. Thats what I was trying to avoid doing by letting the fuel pump, pump it out. it did cross my mind that some gas might still be in the tank, but I was thinking if I added enough good gas in along with fuel treatment or whatever is feasable, the good gas might...overwhelm...if you will...the bad gas.
Nonetheless, the previous owner of the car had cut an access hole to the sending unit. Not too happy about that but do you think it would be wise to try to access the remaining bad gas from the top and try to pump it out? i'm leary about that because it would take an electric pump. Unless I syphoned it out the old fashioned way. Anyway to avoid pulling the tank would be a plus. . But if I have to I will.
When I first crank it, it idles just fine for about 15-30 seconds. Then it starts to cut out, run rough. When I "rev" it up it spits once. You have to put her to the floor. But now I do have what seems to be a rear seal leaking, possibly from it sitting so long.

In any case, I'll get a new pump and go from there. It seems the motor will have to come out regardless since I now have the leak.

Vader

If the old pump is still operable, you can use it to empty the tank.

Are we certain the pump is incorrect? What is the fuel rail pressure at idle?

1991CamaroRslow

iTrader: (3)

The actual connection for where your fuel pump goes onto the hanger should be different. On the TPI cars there's a block that the nipple of the pump attaches to, on the TBI cars there's a little length of fat hose. This fat hose will eventually explode due to the pressure and leave you with all kinds of headaches, trust me this is experience talking here. Get a Walbro 255 from eBay and put it on your old hanger with the attachment block and sender, that TBI pump won't work on your car, it'll run it lean if you try (and manage to) drive it and fry something in the engine, or more likely it won't run at all over idle. If you stick the high pressure pump on the TBI hanger you'll have the problem mentioned above. Hope this helps man.

1991CamaroRslow

iTrader: (3)

On the bad gas, don't worry about it, the pump will get most of it and the rest will be diluted over time by good gas. I had a lady pour about 2 gallons of kerosene into my tank when it was sputtering on me once, that was a memorable trip, no joke the car managed to run it for 2 miles to town!!! It was one of the most awful things I've ever done to my car, a giant trail of black smoke and all kinds of horrible sounds, car wouldn't rev over 1600 rpm but it made it to the gas station and runs fine now.

Time

no, the old pump I took out does not work.
just the one from the RS.


As far as the walbro 255. Thats the pump right? just wanna be sure since I never heard of it. and it will work on the sending unit that I have from an RS?
btw: I may have to get another sending unit since it is not registering the fuel level correctly. it shows I have 3/4 tank of gas which I dont. I can get another sending unit from a boneyard pretty cheap.
so, the new fuel pump will have everything I need to mount it on my existing sending unit?

1991CamaroRslow

iTrader: (3)

On the TPI pump hangers (fuel level sender and pump attachment thing) there is a block that the fuel pump attaches to, it's like a black square that the fuel pump nipple clamps to, this is designed to handle very high pressure and be immersed in fuel. The TBI pumps (Rs pumps) have a short lenght of fat hose and 2 hose clamps, this is meant to handle low pressure and be immersed in fuel, if you stick a high pressure pump on there it will work for a minute then it will blow out and give you a huge headache. Your options are to rig up a piece of R9 hose (auto parts stores call it "fuel injection hose" and usually don't even know they carry it until you explain exactly what you need) and hose clamps to the fuel pump nipple and the RS fuel line, or do it the right way and get a TPI pump hanger. I currently have the R9 hose and clamps working fine in my car because the fat length of hose blew on me, but i bought a TPI hanger and plan to swap that in this coming spring. The Walbro 255lph pump is avaliable on eBay and is simply a high output, tough as nails pump. Some say it will flow to much fuel for the Camaros but this is BS I have it on my car, my fuel pressure is stable and everything works great.

Time

We are talking about a Fuel Pulsator, right?
I just removed the sender unit to remove the weakling pump and noticed it betwenn the pump and metal line.

Vader

Yes, he was talking about the pulsation damper. That can be replaced with a section of regular fuel hose and two worm screw clamps. As for the fuel level sender, you're on your own. They're not fun to replace, as you well know, so make sure you get a good one.

Time

Ok, let me be sure on this.

So I cannot use the fuel pulsator? I should take it off and use a new hose w/ clamps instead?
I did notice it only just "slips" onto the pump & line as opposed to a hose that is clamped on. So that did worry me as to holding up on pressure.

1991CamaroRslow

iTrader: (3)

Yes and be SURE you use R9 hose. I've had the R6 hose and the regular fuel pulsator blow on me, the R9 length of hose has held up.

1991CamaroRslow

iTrader: (3)

BTW that's one sharp looking car Time, gotta love those rS rims, best rims they ever put on a 3rd gen