Engine won't turn over with plugs in ???

[rpauti]

Acquired this 98 xp....checked compression 150 both cylinders....new starter,battery(12.4v),and solenoid....with the plugs removed, the engine turns over easily and smooth....with the plugs in, the engine won't turn over.....no liquid in cylinders...no resrtiction on impellar.....i'm puzzled...any suggestions will be apreciated....thanks in advance

 

[- BiRkS_]

12.4V is a little low. you want 12.6-12.8V. Is your battery new? has it ever been load tested?

tight connections? clean connections? check the ground at the engine, and the pos wire going to starter, make sure they are tight and clean as well. What starter did you put in? anything other than OEM should be removed and replaced with a rebuilt OEM (kit is only like 25$)

 

[richardpr]

had that problem. engine was full of water lol

 

[- BiRkS_]

had that problem. engine was full of water lol

He said there wasn't anything that came out of the cylinders with plugs out. But I cringe anytime I find water in an engine. Oil is OK, not WATER!

 

[richardpr]

it was in the crankcase, not cylinders

 

[Coastiejoe]

So it cranks ok when checking compression but not with plugs in,,,,

What does the voltage on the battery read while the engine is TRYING to crank with the plugs in?

 

[rpauti]

the battery is brand new....added the electrolyte and trickle charged it for12hrs..all connections good....I didn't ohm the wires though so I will check that.... will check voltage at starter while trying to start..... it turns over really fast with plugs out. Was doing the same thing with original electrical parts. I'm getting two beeps when I insert the key...hit the start button and it trys to turn over????? don't think it is electrical .....any other suggestions appreciated.....thanks for response......peace out BIRKs

 

[rpauti]

yes sir ....... I had removed the carbs to check them over, engine was sitting up for a year with old gas......this is my first rotary engine.... I'm a diesel mechanic.....I had sprayed fuel/oil mix into the intake and actually got the engine to fire up briefly...3 secs.....so I figured I was good.....when I did the compression test after warming cylinders, I did it with the tester gauge on one and the plug out on the other.....This engine is a 787......I can turn at shaft with a pliers fairly easy ....not feeling a tight spot......thanks for the response.....any help appreciated....peace out Coastiejoe...

 

[rpauti]

Thanks for the reply richardpr.... I'm new to the 787 rotax engine.....could you tell me how to drain the crankcase.....the engine was set up for a year in a garage and hasn't seen the water since.....i'm not to familiar with the lubrication set up....hose going to each side of engine from reservoir......maybe excessive oil in the crankcase?????....Don't know....the starter, battery, and solenoid are new...... I filled and trickle charged the new battery myself.....same size battery as the one that came out.......thanks in advance....peace out

 

[rpauti]

yes sir.......turns over nice and fast...smooth.......I will set up volt meter with gator clips so I can do this and check at the starter while trying to start......How much do you think the voltage drop should be???? I will also ohm the positive cable and the negative cable....I did find and repair a corroded connection on positive cable battery side.....cut the wire back about 1" and crimped on a new heavy gauge connector 1/4" hole for battery bolt.......thanks for advice....any help appreciated....peace out

 

[Coastiejoe]

It needs to be near 12 volts while cranking for all things to function as designed. 11.8 ish is good. If it is near 11 volts then there is an issue and the starter won't have the umph it needs to crank properly. At 10.7 volt the MPEM does not function.