I have had it idling for about three hours now. Long enough to burn 4 or 5 gallons through it. Same results. Got to go get more gas in the can now I just got done checking the fuel system and it seems to be working although I can barely here the pump running. I have to almost get down with my ear close to it to hear it making any swirling sounds.

 

I don't think it would be the fuel pump.

One way to check that is to prime the fuel system. Its in your Haynes Her Way manual. You jumper some check connector somewhere.

You can hear the fuel pump turn on without any of the cars systems on so its nice and quiet when you're listening for the pump.

 

Update: Changed out the AFM. No change. Changed out the ECU/I no change. Rechecked all hoses and connectors... a-ok. I'm thinking this has to be a problem in one of two areas. Fuel or throttle problem. Again, if I slowly raise the accelerator from 850 to 2500 I'm fine but after that I get the honking sound and a loss in power and it will not go any further up in rpm's. If I go from idle to WOT all at once the same thing happens right away with the rpm's only raising to about 1600. This condition is what is bringing me to believe it's starving for fuel or throttle not opening properly. I did look inside the throttle body after removing the accordian pipe and had my son floor the accelerator and all the plates opened. So that appears to be ok.

On the fuel. I can barely here the pump running even with the carpet and plate off.. but it is running. I got another fuel pump from the local yard and I am going to change that out tomorrow. One thing on the fuel lines that is confusing. I looked at the FSM for 86-88 NA (not the Haynes Her Way manual... that was funny Templeswain) and the diagram shows the fuel return on the front side and the feed on the back which is exactly opposite from what I've heard on this board. It is an 87 GXL. Now, all of the other models and years show the fuel the way I have it now which is feed on the front. Can anyone verify this???? Anyone concur with my diagnostic assumptions here???????

 

Any thoughts on this last post oh wise rotor-heads?

 

Honking sound. I have no friggen clue what you're talking about. You need to get a video or at least a sound clip up, similar to what 49kmilet2 did when his car blew both rotors...his description was poor, but when I heard the sound on video, I knew right what the problem was. Upon disassembly, sure enough, he had one good apex seal in the whole motor.

Other than that, I say check your timing. I have had cars that would NOT go above x rpm regardless of what you did, what you changed, etc. Then I realized my dumb *** timed the CAS with the crank pulley marks not aligned. IF the engine starts up and runs, you should have no trouble revving the **** out of it.

BTW, revving to 4k is fine for a rebuild. I rev mine up to 3k or so when they start, hold them there manually for several seconds, then adjust teh idle to around 2500, then down to 2000, then 1500, and leave it.

 

I have an 87 GXL sitting in front of my house right now.

Need some pictures?

Or just tell me what you want me to do, And I'll verify its fuel line direction for you.

 

Temple, just tell me which fuel pipe (front or rear) connects to the filter. Or easier which one connects to the return. I don't think this is the problem or I don't even think I would have fuel to idle but I'm leaving nothing up to chance at this point. Thanks

 

Here's what I think you're talking about.

I'm going to put this in my terms cause I am a little confused as to what you mean by front and back.

When I'm standing on the drivers side looking over the block by the oil cap there's two metel lines that are connected to rubber fuel lines.

One of these metal lines should have a white dot painted on it.

The other shouldn't.

The one with the white dot is the return.

the one without the white dot has its line coming from the fuel filter.

Again:

The metal line on the left is without the wite dot, and it is the feed from the fuel filter

The metel line on the right, with the white dot, is the return.

I just took a picture and I could e-mail it to you.

 

Hypntyz, thanks for the response. If you forget the honking sound for a second the problem is really with reving and rpm's. Again, if I gradually build rpm's to 2500 I'm fine but then it just wants to stop building rpm's and is trying to suck more air in through the AFM and that is where the noise is coming from. If I go wot from idle this condition will start immediately... sucking for air and no rpm's.

 

Once again, same for me, only slightly higher RPM.

 

Having the same problem.... used to be intermittent, at various rpms... now I can't get about 1500 rpm...

 

My next step is to do a compression test but with the engine idling so well as well as easy start-up each time I'm doubting I have low compression or an internal problem. I hooked-up an ECU tester and the only code it produces is for the O2 sensor which I can't imagine would cause this problem.

 

I'm going to do the compression test tomorrow. What kind of results should I expect on a newly rebuilt engine? I replaced almost everything internal in the engine down to new main bearings. I used Atkins two piece 2mm apex seals. Rotor housings were in very good condition.

 

If it is a newly rebuilt engine, the compression test may not come out as well as hoped. Rebuilt engines still in their break in period increase compression as they are driven more. How many miles have you put on it so far?

 

I have about ohhh about .5 miles on it. It can't be driven the wat it's running. I have about 8 hours of driveway idle though and that's going beautifully.

 

more info: A couple of other items I've checked...

- compression is good

- I am definately running rich (black plugs) but I have timed the beast about three times including resetting the CAS. It's fine

- I checked the airpump... it's fine

- Now the fun part. Checked the ACV. It is blowing air out the cold air pipe even at idle. FAS says it shouldnt blow until 1500 rpm's. Also the solenoid does not blow any air at all (look at FAS if you want to know what I'm talking about). Sooo I suspect there may be a problem there. Anyone think that the description of the problem could be related to the ACV?

- Now, one other thing I have been thinking about which is the ACV outlet into the manifold. Not saying I did this BUT if I put the manifold gasket on wrong and covered the small hole, would that cause either ACV problems or some other kind of blowback into the intake. I'm thinking that there must be negative pressure coming back into the upper intake and back out to the airbox which is causing the FSM to get confused and start the weird sound which is the flap opening and closing rapidly. Thoughts?????

-

 

I just went and looked at the two spare acv that I have and I really doubt you did that. I don't think you would have been able to do that. It only fits on one way. The other way would scream "wrong!".

However, there is this funny looking circle valve that's flat inside. It looks about the size of a nickle and is definately a valve that only lets air in, in one direction.

When i have taken these Acv's out before sometimes it likes to just pop out. Usually in such a way that you have to go on an deep sea engine expedition to find it agan.

Maybe it popped out and you didn't notice it? I donno.
Just trying to help.

If it did, I could send you that valve. Provided the valve is still in good condition?

 

Okay, scratch the valve.....Mine's gone.

Anyone else know what this valve does besides making sure pressure is only in one direction?

 

Thanks Temple. I was actually referring to the manifold to engine gasket. There is a small hole in addition to the large exhaust holes. I'm just grasping here. Not sure if I did or didn't put it on correctly. Just wanted some confirmation before I start tearing off the manifold. Your idea on the little valve inside the ACV is a good one. I thought about that yesterday but I'm sure I put it on and in the correct position.

This is getting frustrating. I just don't understand how I cna have good compression, smooth idle, timing perfect, lots of fuel and get these results???? I'm stumped.

 

Cool. Well I have lower intake manifold and an engine block siting on my shelf somewhere too.

I'll go look for it.

Although I think I'm the only person who is actually cabable of reversing that gasket......I'll look at it.

 

Well, looking at it and I really doubt you could have done that. The gaskets dimensions are not symetrical so, you would notice a gaskget flange sticking out about a 1/4 inch off the right hand side top where you put a bolt.

On the other hand, I was reminded that the Acutators intended to make the ports open and close are located on the lower intake. Both port mechanisms are turned by this rod that has to join to these sleaves.

So maybe, you put the sleaves (that are recessed inside the engine block) in the wrong way?

And that's why the intake ports aren't opening correctly?

Or is it possible that you missed one or both of the sleaves entirely when you put the lower intake manifold on in your rebuild proceedure?

 

One other noteworthy thing about the rod that connects to the sleave is, its actually not a solid rod at all.

Its actually a spring. Boing! So you definately could have missed sleave and the spring is bent slightly. If you do take the intake off be sure to verify if the sleaves are in their correct position.

 

Thanks Temple. I was very careful when putting those in. Checked the clocking about 5 times.. lol. I think I am ok there. My understanding is they don't start to open until about 3500 rpm's. Anyone confirm that????

 

Call mazdatrix about the ports opening and closing.

Just say, "Yeah I was think about puchasing another ACV because there's this chupacabra in there......"

Mazdatrix will say, "Chupa-what!?!".

"Oh yeah, you know the chupacabra, My rex won't go above 2500 rpms. By the way, at what rpm's are the ports suppose to be opening."

Anyway. I have every part and then some to make a whole new engine outside of the the car. So if there's something you want me to go look at, don't hesitate to ask, I'd be obliged.

 

You're funny Templeswain. Many thanks for the offer. I started a new thread on this... new rebuild odd results if you wanna see some other ideas. Stay in touch bro. I'm gonna get this resolved. Take a look at the other thread for some observations of others as well as some updates I posted.
https://www.rx7club.com/forum/showth...postid=2110268

I did a real compression test today just to make sure. I got 101 on the rear and about 95 on the front with all even bounces. Thought that was pretty good for a fresh rebuild with no miles. Sooo, I know it's not a rebuild problem. Could be those damn valves though... now you have me wondering even though I was careful putting them in.