kaplgar

I'm trying to get my old '83 RX-7 GS 12A manual transmission running again after sitting idle for10 years. It has 163k+ miles.
After draining the tank (no signs of rust), I put 2 gallons of 93 octane gas in, installed a good battery and turned the key to the "run" position. The pump comes on, but no fuel comes out from the 5/16" line at the carb. I then disconnected the fuel pump hoses from the lines, put a small container of fuel under the car and tested the pump pressure (2.4 psi) & flow (2 quarts per minute). I also checked for fuel line issues (none found). It seems to me that the FCV (fuel check valve) may be connected backwards. I can blow though it in the opposite direction to the arrows on the part, but not in the other direction. Bottom line is it's not getting getting fuel to the carb. Perhaps I need to add more fuel, replace the pump and/or FCV. Any info on what is likely to be the problem will be greatly appreciated.

OG BBF

If you can blow through the check valve the opposite way in which the fuel flows then that's very bizarre and most likely your problem as it means the fuel is getting stuck the tank side of the check valve. Try blowing through the check valve both ways, should only be able to one way. The way you can blow though is the direction you need it inline so fuel flows though it but can't go back.

evo_koa

iTrader: (2)

did you replace the fuel filter?

kaplgar

OG BBF -
Thanks for the reply. Blowing through the FCV is only one way (not sure how it got reversed); however, this morning when I disconnected the supply line hose going into the filter and tried blowing into the supply line (back towards the tank), it's restricted (no fuel in the tank). I removed the gas cap before trying so don't know what is doing that because I blew through the line after disconnecting from the tank and it was clear. Is there something in the tank that could be blocking it? Perhaps I could try blowing compressed air into the tank . . . ? Or is that a no-no?

kaplgar

evo_koa -
Yes, I did replace the filter. Thanks for asking.

OG BBF

This is a very curious problem. I think we need to try isolate where the blockage starts and ends.....may sound a bit strange but if you have a vaccume pump like a mityvac or similar....you could fill it with fuel, remove the fuel supply line after the filter, remove the supply line from the carb and place into a container and try pressure feed fuel to the front of the car....if fuel goes into the bucket your problem is before the fuel filter (or perhaps a dodgy pump), if nothing comes out and the mityvac just builds pressure then there's a blockage somewhere after the fuel filter. If we can isolate which end the issue is, then we can focus on that particular area

kaplgar

That was a good idea to put a vacuum pump into play, but I don't have one of those. I did make progress late this afternoon however. Here's what I accomplished . . .
1) Removed the FCV valved and cleaned it (inside and out), then replaced it into its proper location and connected the hoses according to the arrows.
2) With the pump and filter mounted in place on their brackets, I reconnected the hoses per design. but disconnected the supply line hose from the fuel tank (eliminating the tank from the equation).
3) I then suspended a 1 gal. container 1/2 full of fuel from the rear end under the car and dropped the supply line hose into the container.
4) With everything inline from the small container of fuel to the hose at the carb (dangling in an empty container) I turn the key to "run" . . . fuel started flowing after about 10 seconds or so!
That being accomplished, the issue that remains is why the tank seems to be restricted when I try to blow into the supply line hose at the top of the tank.
Is there anything inside the tank that you know of that would cause this problem? . . . if only I could see inside the tank!

kaplgar

Perhaps if I were to spray carb cleaner into the 5/16" supply line steel tube at the top of the tank it might free up some gunk that might be in that pickup tube . . . ?

OG BBF

You could try feed some aluminum wire into the steel supply line to see if you meet any resistance, if you do, does it feel solid or does it feel like gunk. Aluminum wire is flexible so you should be able to feed it in no problem. When you remove the wire you should have remnants of the blockage on the wire if it's of an organic nature. You could try carb cleaner and pressurised air to try dislodge any blockage but of course this could mean that it'll end up in the tank

kaplgar

Update . . .
Carb cleaner did not work. I'll try feeding a wire down the steel supply line after I let that hidden pickup tube sit (for a couple of days) in the 5 gallons of 93 Octane that I poured in there yesterday in efforts to get it flowing.
It appears that the pickup tube is not removable from the tank as I don't see a removable flange. Do you know if that's the case?
Thanks for your help on this problem!

OG BBF

No I believe it is fixed, I sorry I really don't know what else try, if I was living in the US I would happily come down and try solve the issue. Only think I can think of is have a look though the 12a fuel and emissions section of the FSM and literally go though everything thoroughly......here's the direct link.

http://foxed.ca/rx7manual/manuals/1985_RX7_FSM/85RX7(4A)Fuel%2526emissions_12A.pdf

kaplgar

FYI . . .
I got the tank fixed! Here is an update of the steps I took to get it serviceable:
1) I dropped the tank from the car, took it into my home shop and removed the fuel gauge sending unit (which resulted in a 1.75" diameter access hole).
2) I then could see the complete fuel pickup tube that was tack welded to the tank at the factory (and not replaceable), so I proceeded to try poking a flexible copper wire down the pickup tube and found that it was plugged about 3/4 of the way down the tube.
3) After much effort in trying to break loose the blockage, I was NOT successful! It was then that I decided to cut the steel tube off (inside the tank). So I proceeded to rig a tool (using an electric drill, bit extender and modified 3" cutoff disc) that would reach to that point of the tube I thought would be unplugged, and cut the tube in half.
4) I was then able to retrieve the bottom of the pickup tube along with a plastic like material pre-filter that was installed at the factory. However, I learned that I had not sawed the tube off far enough toward the fuel pump to remove all of the blockage.
5) It was then that I decided to saw about a 3" diameter access hole in the large emboss at the bottom of the tank (directly below the pickup tube).
6) This allowed me to see (and access) the end of the tube where I sawed it off and learned that I needed to saw about another 1/4" off the tube to get rid of all the blockage. After doing that I was able to clean up the tube parts and install a short length (about 6") of submersible 5/16 fuel line hose (which I had to special order) between the ends of the (2) steel tubes. I used stainless steel hose clamps to secure the hose.
7) After cleaning the tank (and pre-filter), I fabricating a steel cover (from .112" thick plate). I took it, the tank and the factory pre-filter to my welder friend for welding the hole shut.
8) After reinstalling the tank back onto the vehicle and repairing the electrical connect to the fuel pump, I confirmed that it was getting fuel to the carburetor so I tried starting the engine. It started but smoked a lot and died after about ten seconds (it flooded) and would not start again without eliminating the flooding problem.

Finally, I ordered a carburetor kit and after installing that and making all the necessary adjustments it ran a lot better.

There are a lot more things to fix and I'm sure questions will come up!

OG BBF

With cars of this age there will always be things to do, problems to solve but I'm so happy to hear you finally eliminated that issue which was bugging you for so long! wish you all the best with the car and the gents of this forum will be more than happy to assist with any questions you may have 👌🏼