I have to change out the fuel pump on my 85 305TPI. I can't seem to get more than 25-30 psi at the rail and it drops to nothing within seconds of turning the car off. I have a new Holley adjustable regulator, new injectors, all new o-rings and do not smell fuel leaking anywhere. The filter is fairly new too. I have tested the pressure driving also with same results. (I'm assuming it's the pump, don't know what else it could be)

With that said, I need to drop the fuel tank to get to the pump, my question is;
Has anyone done this without having to drop the rear-end out of the car?? I looked back in the records that the P.O gave me and found where he paid a mechanic to change the last one, the receipt only states removing the exhuast and about an hour labor for the pump install, obviously they didnt drop the rear end for 1 hour labor...

Any input from anyone that has done this??

 

It might be leaking down in the tank, there might be a rubber section that hooks the pump to the line.
You have to unhook the shocks & lower the rear axle, not remove it.

 

That sounds a LOT easier than removing it. I was wondering if there were any connections within the tank that could be leaking? The pump is only 5 years old according to the P.O receipts...

Is there any way to test the pump for proper operation when I get to it?

 

The leak I'm talking about is inside the tank.
I'd pinch off the return line, cycle key, watch bleed down rate, if nothing changes, then I would cycle the key & quickly pinch off the feed line & watch the bleed down. If it doesn't bleed down & theres no leaks anywhere, the its leaking down inside the tank.

 

Also you might search this forum for putting a hatch in the back floor to get to the pump when ever you want.

 

I'm hoping there's has not been a hatch put in, trying to keep it as close to original as I can.
I will try the testing with the line pinched later this week.

Thanks for the input!!

 

I do not have a hatch in mine ether.

 

I would put one in & have no worries about it.

 

Which line is the return line? I am assuming the line that goes directly into the regulator is the pressure line...

Also, is there a "relay" under the hood somewhere for the fuel pump? I can hear it cycle when I turn on the ignition, as soon as that relay cycles off, the pressure drops immidately.

Juat trying to rule out everything before I drop the tank

 

The feed line is the larger line, 3/8".
The return line is 5/16".
I wouldn't worry about the relay, your pump builds pressure.

 

you dont have to pull the rear end only the exh pipe not that hard of a job

 

OK, finally got the tank out. Not that hard just time consumming. Getting the fill neck out is the hardest part.

The rubber line connecting my pump to the metal line inside the tank was so bad that the rubber was coming off, so I'm pretty that was where my leak was. Jusy need to get the new pump and parts to go with it and I hope to put it back together next weekend.

 

I'm guessing this is the line you were referring to? It was coming apart inside the tank. Makes perfect sense now after seeing this. Can I replace the "rubber" hose with something else that will hold up better inside the tank? This one was only 6 years old, I don't want to have to go through this again in another 6 years...

 

what in gods name is that! ive never seen a fuel line disintegrate like that before now the question is you sure the pump and or the the hose was replaced ? or was it a quick slap in ? in the history of replacing fuel pumps ive never encountered that before... hmmmm get to replacing and cleaning my friend. btw everyone likes to drop the tank to replace the fuel pump. on my iroc i have the door because as we all know it you be there again and im not dropping the tank on the side of the highway...

 

Usually the new pumps come w/ a scection of hose thats made for immersion into fuel.

 

I am going to be changing my fuel pump soon. What fuel pump are you using as a replacement?

 

Not sure yet... Probably just go with the stock AC Delco. I'm running stock motor with no mods.

Going to get one this week or next.

 

OK, guys got a question...

Got my new pump and about to install it, here's my question though..

Since I dropped the tank, I just want some piece of mind before I put the tank back in, is there any way to test the pumo beforeI pu it in? can i just put 12v to it to make sure it runs?

 

Will the wiring strech to the fuel pump connection? If it does then just use the car's wiring to power it.

 

Does it have to be in the tank to do this? Cause its installed on to the sending unit and when I plugged into the car and turned on the ignition, I got nothing.

I did check the voltage at the connection on the body and it gets 12v for about 2 seconds when i turn on the ignition

 

I just connected mine to the car wiring and turned the key on. Don't leave it on long. Just check to make sure the pump kicks on then turn the key off. You don't want to burn the pump up by running it dry too long.

 

That is a problem. The pump should come on. Double check your wiring on the sending unit.

 

What should I get when I ohm the pump? I ohmed my old one which still came on and got aroun .60. The new one only gives me about .05

I'm thinking I got a bad one....

 

OK, got it workin!! Had a bad connection. i didnt use the new plug that came with the pump at first. Changed that out with the new one that came with and it works now!

I just used standard wire crimps as the previous install had on the ground wire only.

Getting it all put back together in the tank to re-install. Gotta work tonight so the tank install will have to wait until tomrrow.

 

Here is the pump I found. So far so good. Good price and super fast shipping. I should know by tomorrow night or Monday if it works good.

http://www.highflowfuel.com/i-520971...1985-1997.html

 

Fuel pump is in and car is running great. Just need to get my exhaust put back together this week.

The pump took care of my pressure issues. holds pressure now. I beleive it was a combo of the pump going out and that little hose from the pump to the sending unit (it was bad too).

Anyways, I'm a happy camper. Thanks everyone for the input. I know it seems like a small project, but i had to put it on hold all winter due to work and $$.

Now to figure out my next project to tackle....