2012 MSU 500 No Spark or Fuel Pump

[FloridaMan]

I have a 2012 Massimo MSU 500 that died. I found that it didn't have spark and the fuel pump wouldn't run. Checked all fuses and none were blown.

Went through and replaced the ignition coil, HT lead and spark plug. Still no spark.

Thought it could be the fuse/relay box because I didnt' know much about the machine at that point so I replaced it. No spark.

Then I replaced the ECM just because I was running out of ideas. No spark.

I removed the 9 pin connector and hardwired it making sure that they were no wires got swapped. Still no spark.

Then I replaced the wiring hardness. In doing so, I replaced the 9 pin connector with new ones. I made sure all wires were matched up between the engine harness side and the other harness assembly. Still no spark.

I have no other ideas what to do. My fuel pump doesn't kick on and I have no spark. I have 12V on the fuel pump, ignition coil and fuel injector, but no ground from the ECM control.  I unplugged the fuel injector and waited for a diagnostic code but nothing ever came in. It makes me think that the ECM isn't powering up. I've checked for 12V on pins 18 (purple wire) and 15 (white and black wire). I also checked for ground on pin 2 (black wire). All are good.

I am out of options here and I have no idea what else it could be. I have all connections redone and are coated with dielectric grease. I've checked all easy things like fuses and making sure I have 12V in the right placed. I would appreciate any help.

[Ben1098]

Also check the second GND on BLK Conn P. 9.

The ECU is missing an input yet.     My guess is the Pick-up Coil (timing pulse) which tells the ECU the motor is turning over.  The wire for this signal comes out with the stator charging 3 Phase wires and is a shielded cable.  Disconnect at the engine and do a pick-up coil resistance check.  OPEN circuit means DEAD.  These have a nasty habit of a mystery failure and then "heal" after a short cool down.  Since the signal is a thin pulse, you need a Snap-on adapter or a lab scope from an auto shop.  The metal tab on the flywheel tickles the pick-up coil....pulse + and then pulse - as the metal tab goes past the central pole of the coil.  The signal and "gnd" are fed to the ECU by a shielded cable.  These can short down (together) if there is cable damage (smashed) and kill the signal.  Also make sure the Al foil wrapped does not short out the signal at the ends at the connectors.  You can tape the ends to help...used to standard fare but seems to be lacking on the Chino units.

 

Now for the fuel pump.  Do you get the 5 second KEY ON fuel pump run and then shut off?  THE ECU will start the fuel pump again when cranked over.  Happy hunting.

[Bob swink]

On 2/11/2024 at 8:53 PM, FloridaMan said:

I have a 2012 Massimo MSU 500 that died. I found that it didn't have spark and the fuel pump wouldn't run. Checked all fuses and none were blown.

Went through and replaced the ignition coil, HT lead and spark plug. Still no spark.

Thought it could be the fuse/relay box because I didnt' know much about the machine at that point so I replaced it. No spark.

Then I replaced the ECM just because I was running out of ideas. No spark.

I removed the 9 pin connector and hardwired it making sure that they were no wires got swapped. Still no spark.

Then I replaced the wiring hardness. In doing so, I replaced the 9 pin connector with new ones. I made sure all wires were matched up between the engine harness side and the other harness assembly. Still no spark.

I have no other ideas what to do. My fuel pump doesn't kick on and I have no spark. I have 12V on the fuel pump, ignition coil and fuel injector, but no ground from the ECM control.  I unplugged the fuel injector and waited for a diagnostic code but nothing ever came in. It makes me think that the ECM isn't powering up. I've checked for 12V on pins 18 (purple wire) and 15 (white and black wire). I also checked for ground on pin 2 (black wire). All are good.

I am out of options here and I have no idea what else it could be. I have all connections redone and are coated with dielectric grease. I've checked all easy things like fuses and making sure I have 12V in the right placed. I would appreciate any help.

Did anyone figure out.?

[Bob swink]

Did anyone figure out massimo no spark no prime

[Ben1098]

Make sure you have a IGN PICK UP COIL PULSE SIGNAL AT THE ECM.  This pickup coil is located on the stator assembly.  The 3 heavy white wires are for the CHARGING SYSTEM feeding the VOLTAGE REGULATOR.  The PICK UP COIL comes out as 2 wires going into SHIELDED CABLE.  A broken wire (either one) will Kill the IGN PULSE signal.  A short of the cable foil (GND) will KILL the pulse.  The PICK UP COIL is a heat sensitive part and has thermal die problems.  A resistance check back from the ECM should have the spec'd value.  Open is a harness problem or OPEN PICK UP COIL.  Short is harness or shorted coil.  Check at the engine case wire exit for your situation.

I have had 2 situations where the starter hot wire was wrapped into the harness TOO CLOSE to the PICK UP SHIELDED CABLE and overwhelmed the WEAK IGN pulse which in turn screwed up the ECM for the TIMING PULSE INPUT.  Physical separation is required.  In this situation, sometimes the the engine would start IF......the operator released the KEY from START position to RUN position WHICH IN TURN STOPPED ALL THE STARTER CURRENT SPIKES BEING INDUCED INTO THE PICK UP INPUT.......GOOD pulses now and it starts and runs.

NOW THE WHY?  The machine has run for several years BUT then starts the intermittent NO START problem.  The ANSWER.......the starter BRUSHES and ARMATURE COPPER BARS ARE WORN------GENERATES MORE RF NOISE IN THE HARNESS..   REBUILD THE STARTER or best BUY A NEW ONE.

[FloridaMan]

The problem has been fixed. The purple wire was measured to have 12V with the key off. The white/black wire was verified to have 12V that was switched with the key. What I found was that the purple wire goes down to 7V with the key on. There was some kind of damage in the harness between the fuse/relay box and the 9 pin connector. Ran new wires for purple wire to the battery with an inline 5A fuse. Ever since then, it's been problem free *knocks on wood*. 

[Ben1098]

GENERAL ELECTRICAL TEST INFORMATION FOR TESTING POWER AND GROUND CIRCUITS.   GEM FOR ALL ELECTRICAL MYSTERY T/S.   SAVE AND print out.

            6Vdc    12Vdc     24Vdc      36V and 48Vdc (golf carts)     120/120/240Vac    125/208/208/208Vac     125/208/125Vac/240/240/240Vac

Added to this problem because  his real problem was a high resistance +12Vdc feed to the DELPHI ECM.  There are two (2) =12V feeds and two (2) ground feeds.  +12V feeds are the ALWAYS  HOT and the KEY ON.  The fella used one of the them thar new fangled DIGITAL VOM.  He could have saved him T/S time if (maybe) if he would have used an ANALOG VOM------- those relics from the past that had a needle meter and scales.  The KEY difference is the Digital "sips" power from the circuit under test.  The Analog meter requires some electrical power from the circuit under test A LOAD.

EXAMPLE of testing load current.  WEAK or DISCHARGED BATTERY.  You drive an OLDER car that does NOT have the AUTO headlight function.  You go to a party and it is raining.  Wipers=Headlights.  You exit the car and forget the low beam headlights draining your battery.  Party over and your car is easy to spot because your's is the only one with YELLOW headligths shining.  CRAP!  Gonna need a jump.  You have to try though.  Turn off headlights....dash and dome light are back and bright....small load.....head lights were YELLOW.....bigger load.  Now for the real test.....crank over that BIG BLOCK under the hood.  You have the solenoid click, Die. Click.  Die.l  You got the death rattle.  GO LOOK FOR A JUMP.  The reason for the above story IS an easy to understand electrical T/S problem.  It could have just as well been an lightning damaged Phase A MAIN BREAKER in your home.  You use your trusty HF $5 Digital meter and have a good solid 120/120/240Vac on the down feed up top.  You check breaker buss for A and B  and find good 120V if the nothing is running on the circuit.  The electric dryer spins the drum (motor is Phase B side) but the clothes won't dry...heating element is a load across A & B......BUT all the house lights that went out and cycled with the wash cycles AND then you started the dryer and the lights are back on to stay.  Digital meter says your are GOOD.  You have the haunted house.  This is based on true stories....Worst was a farmer required 2 visits from Power Company and 3 visits from "electrical repair companies".  Called and I drive 90 miles to T/S.  Their problem was a water well dead and 300 dairy cows.  Running a tandem axle water tanker 24/7 for a week from Mt Vernon.  Elapsed time 15 minutes (outside panel by the 7 grain bins were water proof).  Used a Digital meter first then my trusty WIGGY.  WIGGY is a selenoid movement AC/DC voltage tester.......HUNGRY voltage tester.  It presents a load to circuit under test......SPARKS on Disconnect. 

The problem with the house circuit is dependent on the load presented thru the resistive connection (kink in the water hose) of Phase A.

THE TESTING GEM......GO BACK TO THE 70's AND DIG OUT YOUR OLD SNAP-ON OR MAC TOOL TEST LIGHT.  The one that had a full sized screw driver handle and stabber probe and the long chord clip for Gnd  (and for +12v when chasing Gnd problems).  The light bulb doesn't "sip" circuit power like a Digital VOM.  FEED ME !!!!!.  I had 2 of the probes....one with the stock say 100ma draw on 12v.....AND a second that had the mid 60"s dome light bulb.  FEED me BIG TIME. 

In the above +7v on the purple wire BEFORE the KEY ON (ECM not drawing power to run its output drivers) was +12V....... AFTER the ECU was turned ON (ECM now alive and drawing more than the standby power) he dropped to +7v.  Kudos to the fella for catching the change on a ALWAYS HOT full power circuit.  The ECM was too much of a load and dropped the supply by half.  WITH THE ABOVE LIGHT BULB TEST LIGHTS.................ONE tester WOULD HAVE HAD A DIM GLOW......THE OTHER (DOME LIGHT DRAW WOULD HAVE BEEN DARK.                  BEN