theDevilX

Following on from my last post (quite some time ago) I have a non starter S4 NA FC.

It starts on easy start but immediately dies.
I've replaced the fuel pump and filter, with the fuel pump test connections bridged there is fuel coming back down the return pipe.
I have spark as well.

Engine has been deflooded numerous times using all procedures so I don't think thats it.

I don't have a rotary compression tester, but I do have a standard one.

I took the peak reading from both banks, which was 122 psi front, 135 psi rear.

Then I turned the engine over with the pressure relief valve held, to check how 'even' the pulses were, I've uploaded a video of testing the front bank and it seems to me that all the cylinders seem to be pushing the needle roughly the same.

The video is of the front bank, but the rear was the same, just a little higher.

Edit:
New video.
https://sendvid.com/4uswqcs1

Any thoughts?
Thanks

DC5Daniel

iTrader: (10)

Starts then immediately dies? Usually bad AFM or massive vacuum leak. I haven't had an AFM and stock ECU in years, so I couldn't tell you if the car could run even with the check connector jumped and a bad AFM.

theDevilX

No, it won't start at all.
Unless I spray easy start into the intake, then it will fire and run until the supply of easy start runs out at which point it dies.

Its a restoration project anyway so if I must rebuild the engine then I will, but if I'd really like to get the engine running and focus on making sure it doesn't rust away first.

lduley

iTrader: (1)

yank it, looks like you got 2 good bumps and 1 weak one, that and its hard to see what the #'s are because of the light reflection, but it doesn't look like it barely hits 80

FührerTüner

iTrader: (5)

Yeah that looks like low compression to me. When i do my compression test with the valve removed, i get all bounces over 90, on an engine with AT LEAST 60k (Supposed) miles.

theDevilX

I've removed the valve (rather than just holding the pressure release) and I'm going to run the test again.
As you guys say, 1 bounce looks weak, but I'm not sure if the camera is up to the job as I didn't notice it during the test.

Will report back.

theDevilX

Ok new video.

Same cylinder as before, Schrader valve removed.
To my complete novice rotary eyes, this looks fairly healthy.. Thoughts?

https://sendvid.com/4uswqcs1

FührerTüner

iTrader: (5)

That looks great IMO.

arghx

iTrader: (3)

you really should be correcting it for altitude and cranking speed per the service manual. I created an Excel tool/Google spreadsheet to assist. See this thread:

https://www.rx7club.com/2nd-generati...urate-1099066/

theDevilX

Thanks, unfortunately I don't have an external tachometer, all I can say is that's its a brand new battery, fully charged, my elevation is 53 feet.

I'm not too concerned about the actual exact readings, just trying to see if maybe I have a damaged seal, or compression so low it wouldn't start.


If the compression looks good enough for it too at least run, even if badly then I'll move onto what else could be stopping it.

lduley

iTrader: (1)

Check your rear rotor too. Usually the rears go out before the front

theDevilX

Already did the rear, I took the video of the front one because the figures were around 10psi lower than the back one.

So in theory, the compression there should be enough to at least run?

RXSpeed16

iTrader: (41)

Simple stuff:
Are all these tests with the intake piping installed and sealed all the way up to the AFM?
Fuses (esp EGI) intact?
It looks good enough to turn your attention elsewhere.

Can you confirm you did this test?
Next, I'd check the injector signals at the ECU and check the ECU grounds next.

theDevilX

Yes all intake piping installed.
When I did the compression test the EGI fuse was not in, all the intake piping etc is installed.

When I've been trying to start the car obviously I put the fuses back in. I had to replace the fuel pump when I bought the car as it was inoperative and at the same time I cleaned the tank. (full of crud)

With the fuel pump test connector bridged I'm getting fuel back down the return line from the fuel rail (when I take the hose off.

I'm not sure what you mean by the check connector, although I did try starting with the fuel pump connector bridged to see if it made any difference, but it didn't.

I'll dive into the service manual now and look up on trouble shooting the injector signals like you've suggested.

theDevilX

Apologies for the double post, this might seem a silly question, but the fuel lines too and from tank as shown in the attached photo.

In the service manual they are connected with the the feed on the right and return on the left. However in my car it's the other way around, I did some googling but I couldn't find many photos of the area, however following the return hose from the FPR it appears (though they are hard to follow as other stuff is in the way) that they are the correct way around. (Photo of mine attached)

lduley

iTrader: (1)

If its a jdm engine they are backwords.

RXSpeed16

iTrader: (41)

Good catch. Fuel flow direction is important.
Swap them and give it a shot!

theDevilX

Pitch black here now so will give it a blast in the morning.

It's a UK car, so RHD, not sure if that makes a difference.

Unfortunately the only service manuals I've been able to find have been for USDM LHD cars. They didn't seem to be as popular over here, and now there's only something like 90-100 of the NA model left on the road.

RotaryEvolution

iTrader: (30)

well, its obvious the injectors aren't firing or aren't recieving fuel pressure.

theDevilX

OK so I went back to the car and swapped the fuel hoses. With them swapped I got nothing back down the fuel line with the pump running.
Swapped back the other way and I have fuel down the return line again, so the plumbing is correct.

Which as RotaryEvolution said means I guess I'm now checking fuel pressure and injectors.

I've noticed also that the S5 NA diagram shows the fuel lines in the orientation I have them, plus there's a sign on my airpump saying do not remove as engine will not receive oil. Which gets me thinking, my car was registered 23rd of November 1988, is it possible it was an S5 despite being (just) 1988?

FührerTüner

iTrader: (5)

only JSPEC S4 FUEL LINES are BACKWARDS

This thread: https://www.rx7club.com/2nd-generati...kwards-763768/

read the last few posts.

theDevilX

Interesting read, thanks.

lduley

iTrader: (1)

That late i would think it would be considered a 89

theDevilX

Is there anyway of telling for sure?

In the UK this model was simply called the 'RX7 2' and I'm really struggling to find any info pertaining to UK domestic cars.

The chassis number is JMZFC132200104585 if that helps differentiate?
Failing that, I read somewhere that if the BAC valve is on the top of the intake, then its an S4, which looking at the attached photo (excuse the state of the engine bay, it came like that) would make this an S4?

Edit: Just realised its in the FAQ.

lduley

iTrader: (1)

The engine is a s4, upper intake gives it away