JoshuaSchubert

I just got in from tinkering under my rx7 for about 2 hours... most the time was spent trying to make the fuel pump cover go back on... lol... So here is the info, Iam getting 12 volts outa the wires where I attach my fuel pump. My pump is good according to autozone, its makes a pitter patter sound when its wired up at the store. The pump has a PSI of 2.5 - 4.0 will this be suitable for driving, not performance... after reinstalling the pump and doin all the hook ups I went up to the front of the car and got under the hood. I pulled the fuel line off the carb and put it into a measureing cup. I got in and turned the engine over for a good 30-50 seconds and nothing would come out. So I further investigated by plugging the end of the fuel hose with my finger and then reached into the car with my other had and turned it on. I got pressure but no gas. I have half a tank of gas in the car rite now. If this has happened to anyone else or anyone has some input it would be greatly appreciated!

Thanks in advanced, Josh

alien_rx7

Sounds like there is a blockage somewhere. If you're feeling pressure against your finger while you're doing that I would doubt it is on the outlet of the fuel pump but you can do a couple of things to check it.

Take the line off at the fuel pump that runs to the front of the car. Blow through it or shoot some compressed air through and see if you or a partner can feel it at the other end.

Next, take the line off at the inlet to the fuel filter. See if you can blow air back into the tank from that point.

Also, make sure all the hoses are connected up correctly to the different valves and to the tank itself. If you can fuel pressure, that pump is pulling air from somewhere then.

In the Haynes manual (finally grabbed it off the bookshelf, you need to grab one from Autozone or somewhere) it states the two conditions the pump has to meet. First, measure pressure and the results must (for stock) be between 3.7 and 4.7 psi. If you're within that range, you need to next measure flow which needs to be a minimum of 1.16 US quarts after 1 minute of time running the fuel pump.

Summarizing, check for blockages all the way back to the tank and also check for air leaks. Try taking the gas cap off while you crank the engine and see if any gas comes out the fuel supply line then.

Junia

I just had this problem the other day and I thought I had a blocked fuel line. I'm not that good with carbs because I've never worked on one before but my next door neighbor has been working on cars his whole life this is what he did to make the fuel flow again. we pulled the fuel inlet line off of the carb and left the return line on. Then we put the fuel line in a jar so that we can see when we have fuel. Then he had a little bottle with some some fuel in it and pour it down the intake while I turned sat there and cranked the engine. after about a minute or so of doing this off and on as to not burn up my starter, we started seeing fuel coming out of the line so then we plugged it back in to the carb and I sat there and cranked it some more and after a while I could see the little fuel bowl window filling up like it was suppose to. Until I did that I could not any fuel into the carb for some reason and I changed out my fuel filter and I was damn near ready to change out my fuel pump. My neighbor said it had something to do with the pressure in the return line or something but I didn't really grasp it. I was just happy that I was getting fuel again. Now I'm just telling you what we did a couple of days ago that worked for me. I don't know if everything we did was neccessary or not but you can try or if someone else here is real knowledgable about how incoming fuel and fuel pressure works they can explain it. Hope it helps. Oh, and by the way I just did this 2 days ago.

Syscrush

Sorry, I know that this doesn't help with your immediate question, but I have to note that there is a REASON why it's scary to get under your car with just the factory jack. It's scary because it's DANGEROUS. Seriously, don't do this. You should get the Haynes manual (or similar) but if money's tight, then a set of jack-stands MUST be your first priority if you're gonna be wriggling around under the car.

Even if you're using your buddy's 3-ton jack, you should always use jack stands any time you're under the car. A 3-ton hydraulic jack is very unlikely to fail in a dangerous way (unlike the factory tire-change jack, which can just fall over), but it's still a risk with no possible reward. :P

Play safe,

mar3

iTrader: (8)

When you unhooked the fuel pump initially, did a whole bunch of fuel spill out from the line coming from the tank? You didn't unhhok the small white canister that was imline with that and then hook it up wrong later, did you?

Wankelguy

A section of the fuel pickup tube inside the tank runs horizontally and is prone to getting clogged, especially if the tank itself is rusting, or if the car has been sitting awhile. You can check it easily by blowing through the hose that supplies the fuel filter. Sometimes that will actually unclog them for the time being, but they tend to plug up again in a fairly short time. I ended up having to use an old bass guitar string with a little hook bent on the end chucked into my hand drill as a sort of roto-rooter. Just another possibility you may want to check out.
Good luck with it, the fuel system on these old cars is their Achilles' heel.

KehoeAutomotive

What a huge thread for a fuel pump problem. Damn.


Hey Alien....

The fuel volume works even if you use an unapporaved container!!

Cheers!

mar3

iTrader: (8)

Again, PM V8kilr and ask about the infamous gas tank episode....I think the car fell as they were getting out or some such disaster....but he will have the answers you need...seriously...

alien_rx7

Yeah, that was suppose to be a joke on the approved container bit. Just like the whole cellphone at gas station thing. Your cellphone just isn't going to ignite that gas.

Also, don't use a styrofoam fountain drink cup for the test......don't ask how I know that.

Cheers

mar3

iTrader: (8)

that's Chemistry 101 for those that paid attention...