JDSmith

Well we just got it back running…

it was the fuel relay and ecu. Turns out the new ecu was bad as well. A dealer was able to pull a working one off a new unit and it all worked. 
 

the new issue when you put it in reverse it defuels and dies now. The speed sensor is allegedly a common issue, replaced it and same thing. So we just had to leave the speed sensor unplugged and it’s fine. Dealer said Massimo said the causes would be ECU, Speed sensor, or the dash. I’m not replacing the dash so it is just no speedometer for me.

3 hours ago, Greg Kilgore said:

I know its an older post. But I agree that it seems like it is a ground issue. If the original poster would post his resolution that would help.

But some info on relays and power. And if I wrong it won't be the first time.

The relay should supply the positive 12V DC power. To whatever. The ground or negative side should go to a frame ground or back to the battery.

Frame grounds are a lot of problems on many many electrical issues on a lot of vehicles. Whether it's a side by side or a 2001 GMC Sierra dash cluster (don't ask) or a 1997 Dodge Dakota dash cluster (ground point under the kick panel on driver and passenger side).

Cleaning the ground points or running a ground wire back to the battery should resolve the issue. If the fuel pump and relay is good.  

But usually there are many circuits feeding off one ground point. So it would be best to follow the ground coming off the fuel pump to make sure the ground point is making good contact to frame. 

The ground wire can be tested with a multi-meter.

1. Set multi-meter to OHMS.

2. Hold one lead of multi-meter to the other lead of multi-meter. The reading should be 0.0 to maybe 0.2. That will be the reference of the meter and also tells you there is little to no resistance between the leads.

3. Now take the negative side of the fuel pump wire to one lead of the multi-meter. and touch the other lead to a UNPAINTED part of the frame. The reading should be the same or maybe 0.1 more than when you touch the leads of the meter together. 

If no reading or a very high reading that would indicate a bad connection to ground somewhere and the ground point would need to be cleaned.

 

Hope this info helps you or someone. I'm not responsible if anything unwanted happens while you're testing.

 

That’s the consensus. I’ve cleaned and dielectric greased all the connections and no change. I’m having a mechanic check it out tomorrow.

Tank was drained and refilled. Purged line and reconnected. Started and ran for about 15 sec before dying. Noticed at that time the fuel pump wasn’t priming anymore. 
 

I’ve also replaced the fuel pump. So unless the original and then the new replacement was bad, it’s not the pump.

Fuel pump doesn’t even prime. I would think it would prime even if the injector failed.

I will have to look for that relay. From what I can see I believe my fuel pump relay is a little different.  I don’t have a relay checked for this type, but I wasn’t thinking it was the issue as I can feel the click in the relay when key is cycled. No more than they cost and it’s not like I haven’t thrown $400-500 at it already I should just try it I suppose.

I have a 2021 Massimo T-Boss 550. It was submerged in water for a period (hurricane). All filters/fluids were drained and replaced/refilled immediately after as well as air box cleaned. Drained fuel tank, popped the supply line off and key cycled to clear the line of contamination. Reconnected line and filled with fresh fuel. The machine fired and sputtered for maybe 30 seconds and died. Upon attempting restart I noted the fuel pump wasn’t priming.  I checked voltage at the pump and it is 12v. I’ve replaced the coil pack, wire, ecu, ignition (which was failing just prior to the water event) and the fuel pump. The new pump still does not engage. Rechecked with new pump and there is 12v at the plug on top of the tank as well as down at the pump. I’ve popped apart all the plugs I can see, sprayed them with terminal cleaner and applied dielectric grease. Still nothing. I’ve talked to a buddy and he has said it has to be a connection or ground issue.  Anyone able to point me to specific plugs wires etc to check? I’m paying for the answer. 😂