Hey experts, I am wondering when does the FPR open up. When cranking should it open up and would this cause a no start. I turn it over and over and never have any fuel on the return line to tank after the FPR. I verified I am getting fuel to the back side of the secondary rail. Car won't start just cranks and cranks. Have new plugs, Fuel pump, All new injectors and have spark. Have tried another FPR as well no change.

 

open up? it is there to keep the pressure in the fuel rail ~36-39psi higher than the pressure in the engine. so if you put a fuel pressure gauge on the car and jumped the fuel pump you should see 36-39psi.

 

Sorry I assumed it was there to relive some pressure at a certain PSI. Not getting any file back to tank. Car won’t start just turns over and over. I must have an issue with injectors not firing then. Because I have fuel going to threw the primary rail up to secondary where it stays because no start. Not sure why injectors were working a few weeks ago and no way they won’t they are brand new!

 

its possible that the fuel pump is old/weak too

 

Sorry fuel pump is brand new installed two days ago.

 

With 0 reference signal rail pressure should be 38 psi as mentioned and the only control that the ECU has on the FPR is whether or not it exposes it to manifold vacuum, it does not have some way of shutting off or increasing fuel pressure beyond that. If you're not getting fuel back to the tank then you're either not making 38 psi, which could be a weak, obstructed, or improperly installed pump or you've got lines hooked up weirdly/backwards. It's not like the fuel can go anywhere else if routed properly.

 

Yeah went threw it last night and have fuel lines hooked up correctly lines aren’t clogged either was able to blow air threw them both. Also I get fuel all the way threw the primary rail into the secondary. Lots of pressure when releasing main line. Also checked vacuum line from FPR and it is clear. Maybe a giant vac leak somewhere? I don’t know can’t get car started to check that. I don’t think the primary injectors are firing. Car don’t even try to start jus the turns over and over.

 

I’ll put money on it your plugs are fouled, or your engine is flooded. I’ve fixed a LOT of crank no starts by pulling the plugs, sandblasting them, and putting them back in. They aren’t hard to pull on an FC either.

 

Yep no those are brand new to. Im just fed up at this point with it. I wish there was an expert near by to take it to but there isn’t.

 

I'm a little confused as you were first asking about fuel pressure and not having any fuel return to the tank after the regulator and now its an injector related question.

 

I resolved the fuel issue. Checked voltage to primary injectors at ECU getting 11.39 VDC with key on. I got the car to start but it will only do it after I remove the CAS adjust it and plug it back in to the port. The first crank it will start up. I have to keep rev on engine otherwise it drops rapidly and dies. Any ideas on this?

 

sounds like a vacuum leak, but it could be almost anything. if you start testing parts, you will either find what is wrong, or narrow down what the problem could be

Foxed.ca - Mazda RX-7 Manuals

 

Can the fast idle screw on the back of throttle body under the thermowax be so far out of adjustment to cause this issue? Also I have never noticed but are there factory markings on the crank pulley for the timing or just paint? I have the pulley marked with paint markings but I think they may be off.

 

There should be two small indents on the crank pulley. Sometimes a little nick can look like it but they are both the same size dent.

 

the thermowax can cause this, but once you keep the engine running for like 60 seconds or so it should idle on its own.

the timing marks are little divots on the pulley, they were painted too, but that was a long time ago. if you find the mark, and spin the engine to TDC, there is a little cover on the Crank Angle Sensor (CAS) and there is a little plastic plug in the cover, take out the plug, put the cover back on and one of the big teeth should be centered in the hole. put the plug back. if the tooth is not lined up with the hole the timing is off enough to be a problem.

 

So I did find the marks after running 1000 grit sandpaper lightly over the edge of the pulley. They were no longer painted so I remarked them. The timing was off or just past the indicator pin on the cover. I have the CAS adjusted and plugged back in after getting motor to TDC. I have another curious question. My charcoal canister I am missing the smaller metal vac line that runs along the firewall and down back to the fuel tank. the other runs over and attaches to the side of the the oil fill tube. Would this line cause a vac leak in some way. I don't know alot about the charcoal canister other than its there to relieve gas tank pressure or something like that.

 

yes the fumes from the tank go to the canister, and then go from the canister to the purge valve, and then they get sucked into the engine to be burned.

i suppose it could be a leak if the purge valve is bad or not hooked up right or something, ordinarily there isn't much flow there

 

Where is the purge valve? I can tell you the line that runs from the canister back to the tank is totally missing all the way back to tank. Is this the one located under the right rear wheel well? The car was saved from being swapped over to a V8 setup. Was a roller when I got it had to transfer engine, trans and harness's over from my 86 N/A roller is an 88.

 

purge valve is a round thing on the vacuum rack