Home rebuilt rotary engine not starting

Yeah, at 122psi compression, you should have an engine that is really strong at lower RPM.

If the gas is old it may be as simple as that. For my last rebuild the car sat for many months. The engine fired up and ran the night I finished getting all the pieces back together. It idled for a while at a friend's garage, took it for a quick spin around his neighborhood and loaded onto my trailer. The next morning I tried to start it to get it off the trailer and it would not start. After trying may things it dawned on me the fuel tank was almost empty and had very old gas in it. Added 5 gallons of fresh gas and it fired right up.

Knurled wrote: Yeah, at 122psi compression, you should have an engine that is really strong at lower RPM.

The compression reading seems high to me. Is it possible that the number is exaggerated due to the possibility of oil still in the combustion chamber?

Either way, I am going to do the hardcore "deflood" procedure and then recheck compression (after playing with timing and the fuel system).

Silly question. Did you test to make sure you were getting spark? Is the CAS set properly?

I tested spark using a spare CAS (Spin the gear in your hand so you can hear the injectors firing too) with the key in the "ON" position. It had spark like that. I could hear the injectors also.

I tried to check timing.... It seems my crusty old pulley doesn't have a clearly legible mark.

I have some other pulleys that I will make sure they have the timing marks and then install on the "E" shaft. I always mark the top of the CAS when installing to make sure the gear doesn't move when installing. I will check that as well (might as well use the CAS I used to check spark...)

Thanks for all the help so far!

Rob R.

Popping the top off of the CAS so you can watch the gear inside during install and make sure it doesn't move is very helpful. The thing with that is being off a tooth won't keep the car from running, it just won't run well.

I have had a GSL-SE engine that tested at 130psi.

There's no such thing as "too much" compression in a rotary.

Oh, I just was surprised because I did not clearance the apex seals...

Update: engine does have 120 psi both rotors for sure!

Got it start but not stay running twice.

I either have all of the idle screws messed up....

Or it is E36 M3 in the fuel line. Drained gas tank. Gas was okayish. BUT, rust in the tank....

I'm gonna try a fuel pump in a bucket experiment to see if it will run like that.

Based on nonacks experience, will a s4 run with tps unplugged?

If I recall, it will, but it'll be crappy.. And hard to start. (Going from memory, it's been about 10 years since I had a s4 with a factory ecu).

Sometimes!

Mine would always start and idle with/without TPS, but turning the idle up helped guarantee it.

Okay, found some rust in tank. Setup a standalone fuel system to feed the rails.

Same issue.

I started reading up on how to set the various idle screws. Got it to start.

I think my tps is bad or misadjusted.

Went to adjust it and my dmm is dead.

Going to go buy a new one.

Will report back my findings later....

And.....

Tps adjustment seems to have it starting reliably...

I still have a hunting idle and slow/ erratic revving when I use the throttle pedal.

Something is still not happy. Starts ever time though!

Thanks for all the input so far!

TPS reading within spec?

That's certainly progress!

Always check for vacuum leaks :)

In reply to 1988RedT2:

Yep!

In reply to WonkoTheSane:

Will do. Imma check timing again too.

Checked for vac leaks. None found.

Put on running cars intake and tps. Same issue.

Weird issue... I wired up a relay from the starter circuit to carry the current through the relay instead of ignition switch.

Every once in a while, the starter will stay spinning.

Can somebody give me a good diagram with the proper numbers to run the relay properly for this application?

I am not looking for the car side info. Just the relay side.

Thanks!

Oh yea, I verified timing as well.