I am rebuilding an 85 GSL (12A Carb). I have measured the pressure at the carb fuel line and it seems to be around 7 psi, and it seems to pour gas ok. When I hook it up to the carb I don't get any spray in the primary's. I put on a glass filter and it only get's about a quarter filled when turning the engine over. I replaced the fuel filter by the gas tank, so that shouldn't be a problem.

Does this sound like the fuel relay or the pump maybe not maintaining enough pressure?

Any recommendations on replacement parts?

Thanks.

 

There are Some things you haven't mentioned
7 psi is high. That said, have you rebuilt the carb itself? The screens at the fuel inlet to the carb may be the issue. Have you cleaned the tank? It should be done.

I don't think you need to replace anything, (cept maybe another fuel filter) just tidy up what you've got. If the tank is funky, a fuel filter can clog in no time at all.

 

you may just want to look up some information reguarding this . There may be some stock fans stock OEM OTHER NONE MAZDA FANS what have similar dimension to the RX7's radiator which you can put in position which come with a shroud and most OEM fans actually cool much better then aftermarket fans .

 

I am on my second carb rebuild, and I took my time with this one to make sure all the screens are clean and the jets are clean.

It seems like the total pressure is good, but the fuel is not flowing. If I put a gentle upward slope on the glass filter at the carb, the fuel doesn't push up and through the filter.

 

please clarify the following:

1. what carburetor you have
2. what fuel pump you have
3. what gauge you're using
4. if there is fuel in the bowls
5. the filters are placed with flow in the correct direction

assuming you have a Nikki, a few things you can have a look at are the accelerator pump (mechanism and the diaphragm) and I also know there is a gasket that can be easily placed "backwards" during a rebuild, but i'd have to search and find which one it was. also, if you truly have 7 pounds at the carbie, it is WAY too high.

 

1. what carburetor you have
Standard Nikki
2. what fuel pump you have
Stock/original
3. what gauge you're using
A water pressure gauge with a air-compressor attachement. Looks like about 5 ot 7 psi, but the gauge is not exact.
4. if there is fuel in the bowls
Some, about a quarter way up the glass.
5. the filters are placed with flow in the correct direction
Quadruple checked the flow directions.

I didn't reinstall the fuel flow valve on the return line. Not sure if this would be an issue.

 

do you already have a copy of the FSM? if not, get one.

you mentioned that this is your second rebuild. I would suggest checking the needle and seat. the floats do probably need adjustment, but check the needle/seat first. some of the rebuild kits apparently come with malformed needles. there are a handful of threads on the subject.

also, for your 7 PSI issue, that is WAY too much pressure! i'm surprised you don't have fuel pissing out of every orifice. i'm not sure why a stock pump is doing that.

I've seen cars run without the valve. I always assumed it was simply there to prevent backflow. so I guess what i'm saying is I don't think it has anything to do with what you're experiencing, but I can't say for sure.

 

How far up the bowl should the gas be?

BTW: Thanks for the replies : )

 

Fuel should be 1/2 way on the glass. You should also put the regulator back in the return line.

 

I have adjusted the floats, and now I think I am down to the problem. My accelerator diaphragm seem to not be creating enough push as the fuel just dribbles into the primaries. Any recommendations on adjustments? I have been fiddling around with the iddle mixture screw, but not much help so far.

 

The diaphragm has a front and back side, must be installed properly. There must also be the proper bb's and weight in the AP fuel passage.