I just purchased a sandrail with a 13b engine in it. I have no clue about the rotary, so I joined your site to learn. I am skimming the forums every chance I get, but I wondered if you guys could point me in the right direction. I am trying to determine what 13b this is.

What I know:

13b with capital MAZDA on it
Turbo
fuel injection
Haltech e6k
msd ignition
ls1 coils? (denso on them)

Current condition:

Sat for 3-4 years untouched. Fuel pump and battery was trash. Replaced both last night and fired it up. Ran horrible, sounds like it might have a plugged injector. It wouldnt rev up. I hit 4k rpm but wouldnt go higher. Also, the oil pressure gauge was reading around 12 at idle. That doesnt seem right.

Previous owner said the motor was still on break in from the builder. I emailed rotary power usa yesterday as they built the motor and I was looking for any guidance.

I am going to continue reading the forums, but if anyone has any advise that would be great.

Thanks guys!

 

the engine is a series 4 turbo II(1987-88), aside from that i can't tell you much about the internals or whether it has the factory compression turbo rotors or not. the turbo is also a factory S4 turbo by the looks of it, but i can't see the cold side to tell you whether it has been upgraded or not.

13psi of oil pressure is definitely low but it also depends on how low the engine is idling, if the idle is as low as 500RPMs then that isn't an abnormal reading, if the engine is idling at 1000 or higher then that is below what i would consider acceptable. double check the reading with a second gauge for reference.

ignoring the oil pressure issue you have to find out why the engine is running like trash. considering the pump and filter were blocked up you might also have an injector stuck open or closed now due to the varnish that accumulated.

1)check compression on the engine by removing the schraeder valve from the hose to the piston compression tester and use the 2 lower spark plug holes. remove the ECU fuse so that the ignition and fuel won't turn on while cranking the engine

2)double check fuel pressure to the engine, it should be at least 35psi feeding to the engine

3)check that all 4 plugs are firing by hooking up a timing light to each of the 4 ignition cables with the engine running

4)if compression is ok and all 4 plugs are firing you can determine which rotor is having fuelling issues by removing the spark plug wires from a particular rotor, if the running of the engine does not change then that rotor is not firing due to a lack of or excessive fuel


most common possibilities:

you have a fuel injector wiring/connection issue
the engine was improperly built which is why it sat
the engine was improperly tuned and broken, which is why it sat
the fuel dried out creating secondary issues within the fuel system outside the pump/tank
someone who doesn't know how to tune the haltech or set it up gave up and left it to rot

you might get lucky and the first is the root problem, such as an injector just not clipped solidly to the harness, a wire inside the clip pushed out of the connector or the injectors simply need to be serviced. but you might not be so lucky and the owner either was oblivious and/or flat out lied and the engine is blown. these engines are quite fragile(they can be built to be a little less like "glass" though), in the hands of an amateur a turbo rotary is the nemesis of any automotive enthusiast. they are very adaptable engines but their shortcoming is that they will always be inferior to piston engines in many ways.

low oil pressure could be a minor issue such as a bypassing front cover o-ring. it could also be an indicator of a much more serious problem. sandrails live in a harsh environment, sand which destroys engines if the crankcase is not vented and sealed properly. if it ever saw sand and had an issue with sand intrusion then the engine won't live long. silicone sealant is your friend with sandcars, it might be messy but it is a necessity. oiled and inefficient dirt bike air filters will also save wear surfaces inside the engine, the last sandcar engine i tore apart with a dry filter had nearly twice the factory spec for wear on the iron surfaces, the filter caught the sand but it could not keep the engine "lapping" dust out which will render most engine parts unusable in a matter of hours depending on the amount of dust passing through and entering the engine.

some of this might sound like scare tactics, because they are. i've seen many engines torn up by sand and many more assembled to resemble an engine that were hardly that once it was time to turn them on. sandrails require even more finishing touches than a regular street car does, ignoring some of those warnings means expensive trips and short engine life. hopefully the engine is fine but once you do get it running throw that filter in the garbage and grab an oiled bike filter that fits, put a dry sand filter over the oiled filter and clean it every outing, also check to be sure the intake has no vacuum leaks by hosing the engine down with carburetor cleaner after the other issues are sorted out, reseal any vacuum leaks until there are absolutely none. then vent the crankcase with both ports to a catch can located below the port levels and seal up any other possible entrances to the crankcase.

 

I really appreciate all that info and advice. I will check everything that you listed and report back this weekend. If the motor is trash then I am going to need to decide if I repair or swap to a different engine.

 

I was able to get some time away last night, so I went into the garage and did some work.

Compression tests resulted in 90psi from both lower plug holes. Is that okay, good, bad?

Removed the intake to access the fuel injectors. Found 3 vacuum ports on the front of the intake with missing caps/cracked caps. Glad to see that. I pulled the injectors and they were loaded with varnish. I tried cleaning all the sand off before pulling the injectors, but that area under the lower injectors is hard to clean. I was looking into cleaning the injectors myself (watched a youtube video), is that a good idea, or should I just send them out?

I attached some pictures. What injectors am I looking at? Modded primary and stock secondaries I am guessing.

Thanks

 

IMO you should just send them to a professional shop to be serviced, if they weren't loaded up and possibly stuck i would say you could try self cleaning but in this case i would suggest:

RC engineering
Witch hunter performance

the first look like modified/uncapped rochester injectors which i would guess by the stamping are rated at 83lb/hr @ 3bar(standard rating pressure) or 870cc injectors. the primaries appear to be stock 550cc/min.

90psi cold is ok, not stellar but it means the engine should start and idle ok at least until warm when another test should be performed. also is that a peak number or were all pulses nearly equal? standard on a rotary engine is to take 3 consecutive pulse measurements as that is a single phase of a complete rotor cycle, so you will have 6 compression readings combined for front and rear. this is tricky because the pulses come very quickly(nearly 4 pulses per second!) so sometimes it takes a bit of watching the gauge to see an average and a possibly low single pulse, even a single low pulse of 60 or lower could mean a damaged seal internally and a horrible idle/power band.

best way to fix the uncapped ports is to weld them shut or jumper a short vacuum line from one port to another. vacuum caps are a temporary solution and usually only last about a year or 2 before they crack and possibly start sucking in dirt/sand. make sure they weren't intentionally used for a MAP sensor or other ECU logging device. in fact find the MAP sensor and it's line before making any irreversible changes to the ports. on the front of the upper intake both top and bottom ports are good reference points for a map sensor so i usually use those first, it appears your map signal line is coming from the center inner port on the lower intake which usually gives a choppy boost signal, but that could be to the fuel pressure regulator, i can't tell by the picture in which case that is fine.

generally i cap the center lower port by the primary injectors, use the higher up lower inboard port for the pressure regulator and use the lower front upper intake port for the map sensor signal. all others are plugged or bypassed. the blowoff valve is fine how it is routed. there's also 3-4 ports on the rear of the upper intake manifold that could be potential leak points.

 

Just got back from RC engineering with clean injectors. Those guys/gals are great. I called yesterday afternoon and explained the situation. Advised they were swamped but they would see what they could do. I got to their shop at 8:30 (when they open) after 2 hours of driving and the door was locked. Waited a bit and a gal came up and was very sorry for being late. Extremely nice, said she would see if someone good get them done for me. I went and grabbed some breakfast and drove around the area killing time. Went back to the shop at 11 and she said they were almost done.

3 injectors stuck closed and 1 dripping. The modded injectors are 961cc and the others are 550cc. I will get them back in tonight and clean all the fuel lines/tank. Hopefully she will run like a champ now.

 

Got her running. Oil pressure picked right up. Feeling much better about this thing now. Two spark plug wires were switched too. Thanks for all the help

 

glad i could be of help.