Quantcast
Jump to content

Can anyone tell me if their MSU 500 F-PUMP cycles when...


Recommended Posts

Thank you for the reply. That was my thinking but I just bought this one as-is so I wasn’t sure. The service manual doesn’t say much but I’m thinking the only part that would effect the fuel pump, injector and spark would be the ECU. I thought possibly bad ground but it looks ok and the engine cranks over great.

 

Link to comment
Share on other sites

If your not getting spark or the fuel pump isn't priming, you may just have to replace the ECU. There may be some way to test it, but I certainly don't know. I'm flying blind with mine. Don't want to pay for the manual if it ain't worth it. 

Link to comment
Share on other sites

If you bought an MSU 500, you will soon see ITS NOT WORTH IT ... Ihave had problems since the 1st day I bought it new. at Tractor Supply .. and Massimo has refused to pay one dime of repairs .. its been in the only repair shop in my state that will still even work on Massimo, 6 times  .. and only if you pay cash.. 

  • Like 1
Link to comment
Share on other sites

Find the Delphi ECM.  Should have 2 connectors----gray and black.  There are two +12vdc inputs.  One (pin 18) is ALWAYS HOT (like memory on radio) and then the other(pin 15) is hot only with KEY ON.  Don't have ECM pin out handy so I can't state which color connector.  With KEY OFF, remove both connectors (identical except color) and find the fine print molded pin numbers.  KEY ON.  Needle probe (don't stab and ruin the terminal) the pin(s) number looking for the 2 +12v inputs.  After finding, KEY OFF to see if pin 15 goes away (check to see if you are in the right track).  Problems found in past....fuse blown, smashed connector, mouse house chews, and loose connector. 

There is not a good wiring diagram.  The same DELPHI ECM module (retuned) is on late B & S   FI   V-Twin lawn mower engines and the pinout can be found with YAHOO search using  DELPHI ECM PINOUT.

Without the two supply pins, the ECM plays dead....check before spending $$$$$$$$$$$$$$$$$.  CHOW

 

Link to comment
Share on other sites

Ben...Thanks a lot for the info! I’ll check it out. 
Joe... This post is asking “does the fuel pump cycle when the key is in the run position”  NOT  “what’s your opinion of Massimo”

I know it’s not the same quality as my Teryx,  It’s a project machine that I payed $200 for.

Link to comment
Share on other sites

I bought an almost NEW swimmer....drunk fishing buds went to river....to not get a DWI....left MASSY at river....best part....left keys in the ignition....river sandbar recovery.  Hoped for best with this pig in a poke.  Sanded piston/cyl.  Crank bearings "rough".  Even the transmission bearings had multiple  bind spots.  New oil pump.  Still money ahead.  The rear output shaft was leaking BEFORE the swim by the oil slick on present.....BTW, watch this very close....sealant gets hard and leaks not at the seal BUT thru the spline...NICE.  That was 4 years ago....keep the oil level up and CLEAN and watch for air lock in coolant.  Special bleed procedure...FRONT RAISED about a foot...makes radiator higher than engine head bleed screw.  The Al tubes that run in the bottom floor pan HAVE TO HEAT UP WHEN WARMING UP MOTOR....this means the coolant is flowing to the radiator.  BTW, it is a YAMAHA RHINO clone with motor parts interchangeable......I suspect the cam with it's compression release was made by the same SUB......I worked on BOTH units that the weld assy step was WRONG EXACTLY IDENTICAL.....so my spare cam (modified/fixed) went into a RHINO.

My experience......they all have problems (repeat problems)...worst is hillside + idle oil failure (crispy head).  Back to RHINO/HISUN (these motors are in everything....big box).  Common failure in R, Hisun fixed with a more robust bearing so these parts are not interchangeable.  Electrical problems...don't go there.  Ho would not start while cranking....will catch when starter is released.  Even a "solid" design will fail when the starter hot cable is bundled with the pickup coil signal wires.....same as a RAM with the alt cable trashing the ECM inputs.  Gotta go.

Link to comment
Share on other sites

1 hour ago, IslandHopper said:

Ben...Thanks a lot for the info! I’ll check it out. 
Joe... This post is asking “does the fuel pump cycle when the key is in the run position”  NOT  “what’s your opinion of Massimo”

I know it’s not the same quality as my Teryx,  It’s a project machine that I payed $200 for.

Dont care if it was $1 at Kroger, still no excuse to call ANYONE dumba^^  .. Its still America, we can still have an opinion other than yours ... please disregard any post I make in future.. it wont be for you 

Link to comment
Share on other sites

  • 2 weeks later...
On 2/3/2021 at 9:14 PM, T-boss 410 said:

You should hear the fuel pump run for a few seconds when you turn the key to the run position. It's building up the pressure for starting the engine. 

FWIW--This is how my Hisun  HS400 works,,,

Link to comment
Share on other sites

Thanks! 
I have power to the fuel pump, ignition coil and everything else. I Installed a new Relay unit &  a new ECM and that didn’t change anything.
I’m starting to think the problem may be a bad ground. I haven’t been going that direction though because the starter cranks and all other options and accessories have power. I’ll post more later. 

Link to comment
Share on other sites

  • 1 month later...
On 2/20/2021 at 10:13 AM, IslandHopper said:

Thanks! 
I have power to the fuel pump, ignition coil and everything else. I Installed a new Relay unit &  a new ECM and that didn’t change anything.
I’m starting to think the problem may be a bad ground. I haven’t been going that direction though because the starter cranks and all other options and accessories have power. I’ll post more later. 

The "power to the ignition coil" should switch on and off while cranking the engine. The ECU cuts power to the coil when it's time to fire the plug--the collapsing magnetoc field in the coil primary generates the high voltage pulse in the secondary to fire the plug. If the voltage at the coii's primary is unwavering that is not happening.  Have you tested the coil's secondary to see if there is a spark?

DEpending on how the ECU uses the CKP it is possible that a bad sensor could prevent a spark. Most of these small engines have no cam position sensor and use the crank sensor to trigger the spark, this means it fire at each near TDC of the crankshaft but one of these firings is at he top of the exhaust stroke and does nothing. This is often called a "waste spark" ignition system. It is common in  multi-cylinder 4  stroke/cycle engines to use one coil to fire two plugs on two cylinders that reach TDC at the same time by wiring them in series.

wasted spark ignition
SparkCoilLg.jpg.72c74ef918928e54df1d6db26491b8d8.jpg

 

 

 

Link to comment
Share on other sites

Thanks for the help.
So there is no spark on the secondary side when cranking. I’ve been trying to figure which wire or wires in the harness would effect  all 3, (fuel pump, ignition coil, and fuel injector) I am told that the crank position sensor should not effect the fuel pump or injector cycle? but no one seems to know for sure. 

Link to comment
Share on other sites

4 hours ago, IslandHopper said:

Thanks for the help.
So there is no spark on the secondary side when cranking. I’ve been trying to figure which wire or wires in the harness would effect  all 3, (fuel pump, ignition coil, and fuel injector) I am told that the crank position sensor should not effect the fuel pump or injector cycle? but no one seems to know for sure. 

What model year is your MSU500?

 

Link to comment
Share on other sites

The fuel pumps an the majority of these small EFI engines are not "controlled" externally--I.e. they have just one mission in life; which is to, when powered up, keep fuel line pressure at or about 3 bar¹ (43.5 psi)--if it isn't they run 'til it is.

Have you tested the fuel pump, ignition coil,  and injector individually to see if they are capable of doing what they are supposed to?  If direct wiring shows them them to be operational the problem has to lie in getting power to them in normal operation. It would be quite a coincidence for them to all fail at once, but a Forrest Gump said "It happens". you could also connect a dedicated ground to each and see what happens; ground connections are often overlooked--and just because the engine cranks does not mean all low current ground paths are intact.

-------------------------------------------------------------
¹ - 3 bar is the standard pressure used for fuel injector delivery ratings. Most makers use it or near--39-40.5 psi is not an uncommon spec (Ford likes 39)--in their fuel systems.

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share


×
×
  • Create New...