Fuel Pump Intermittently Priming (solved)

[Rustynutzz]

I have 2020 T-Boss that's been pretty rock solid up until now.   

I haven't driven it in a few weeks so I went out to start it and it wouldn't start initially.  After about the tenth try, it cranked and ran perfect. After shutting it down for a few minutes, it wouldn't start again.  I started thinking maybe it was the injector but that didn't make sense.  Then someone mentioned listening for the fuel pump to prime with the engine off but the key on.  After about the tenth try, the pump would prime and engine would start.

Sounds more like a bad connection somewhere than a bad pump right?  If the pump was bad, it wouldn't prime or run.  Problem is, I can't find where any of the wires coming from the tank, terminate.  They're all wrapped up and merge into a larger set of wrapped wires.

Also, under the hood I couldn't find a relay or fuse for the pump.  Are they somewhere else?

I'd hate to just throw a new pump at it and have the problem persist.

 

Thanks

 

[cliffyk]

The fuel pumps on these vehicles are generally prettuy stupid devices, their only job is to keep fuel line pressure around 43.5 psi (3 bar¹). When powered up they just run 'til the line pressure is as desired then shut down until the pressure falls as the engine consumes fuel. They are not intelligently monitored or commanded. by the ECU--they just do their thing if there is sufficient pressure in the line when powered up  they will not run, I think this is what you are observing. To test it you'll need to monitor the fuel pressure and make sure the pump runs when the pressure is less than 30 psi or so. Or divert the fuel line to a container and make sure the pump runs continuously with the key on--be careful though, at 40 psi gasoline can spray everywhere.

How many cc is your t-boss? As a 2020 it is a LInhai under the Massimo badges--I do not have much info on the Linhai machines yet. However the fuel pump relay is likely a little black box in the fuse block.

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¹ - 3 bar (43.5 psi)  is the pressure standard for fuel injector capacity ratings--most vehicle makers supply them with that pressure.

[TapBoss]

Hey Cliffy,  he's got a slightly different model 550  than mine so 493cc.

[cliffyk]

9 hours ago, TapBoss said:

Hey Cliffy,  he's got a slightly different model 550  than mine so 493cc.

It is most definitely a Linhai-550 then...

I wish Massimo (and others) would stop doing that--493 cc is at best a "500", stretching it to 550 in the model designation is a bit much. Years go I has a BSA 441 Victor. guess how many cc displacement it was?

[Travis]

4 minutes ago, cliffyk said:

It is most definitely a Linhai-550 then...

I wish Massimo (and others) would stop doing that--493 cc is at best a "500", stretching it to 550 in the model designation is a bit much. Years go I has a BSA 441 Victor. guess how many cc displacement it was?

The engine in my Mule is a FE290 though it's 286cc....

[cliffyk]

Close enough--my Hisun HS400 is 393 cc--but "T-Boss 550" out of 493 cc--IDK...

[Rustynutzz]

Finally got around to messing with it.

Pulled the hose and cranked it to see if fuel would spray out and it did not.  Assumed it was the pump so I replaced it and now the second pump isn't spraying either.  I could hear it priming when you turned on the key when I first got the machine, nothing out of either pump now.  Guess it's a power issue.  I've already looked at the fuses and the relays.

Any suggestions on where to look next?  I tried jumping the fuel pump ground to the frame with no luck.  I have a call in to Massimo tech support, he thinks it's a relay but unsure of which one so he's supposed to get back with me.  

[Rustynutzz]

Finally spoke to the rep and there is an relay for the fuel pump, it's just not under the hood with the rest.

It's sitting just above the fuel tank with an plug attached to it, all covered by a rubber housing.  I pulled the plug out and it was corroded.  New one is on the way, I'll update when it gets here.

[Rustynutzz]

It was the relay.  I ended up buying a different one off of Amazon because it took scautoparts.com 9 days to ship the OEM relay at a cost of $42 with shipping.  Also, you cannot find that relay anywhere else on the web but scautoparts.

Heres a few pics of the new waterproof one at a cost of $10 and readily available on Amazon.  Also note that the original relay was mounted horizontally, which let's water in.  I mounted the new one vertically.

 

Here's a link if anyone needs it.

https://www.amazon.com/gp/aw/d/B08D8TSMFV?psc=1&ref=ppx_pop_mob_b_asin_image#aw-udpv3-customer-reviews_feature_div

 

Here are the connections I made in case anyone else does this.

Blue to red white
Black to green
Red to red
White to red black

 

 

[TapBoss]

Nice find!  I need to see if I can waterproof mine before any issues occur.

[Rustynutzz]

Here's the location of the stock relay.  At the very least I would tape up the opening so water doesn't get inside.

 

 

[TapBoss]

Exactly what I was thinking.

[Ridge Runner]

Thank you so much.  I think this is the same machine as the Coleman Outfitter 550.  Does yours have  an inline fuel filter?  Some of the Outfitters don’t, and there’s not a easy access place to cut the fuel line and add one.  When did they switch to Linhai engines?  

[Ridge Runner]

I think I see a fuel canister mounted on the frame rail.  Maybe the T-Boss and Outfitter aren’t the same machine?

[Rustynutzz]

7 hours ago, Ridge Runner said:

I think I see a fuel canister mounted on the frame rail.  Maybe the T-Boss and Outfitter aren’t the same machine?

Yep, that's the fuel filter canister you see in the last pic.  I'm unsure if the Outfitter is the same, hopefully someone will pop in and specify.  Do the above pics look anything like yours?

As far as the relay goes, the one I posted above I bet would work with yours.  A relay is a relay, you just have to match up the amperage.  The one from Amazon above is 30/40 amp so it could easily run a fuel pump, just have to make sure what each wire does before connecting.

[Rustynutzz]

7 hours ago, Ridge Runner said:

Thank you so much.  I think this is the same machine as the Coleman Outfitter 550.  Does yours have  an inline fuel filter?  Some of the Outfitters don’t, and there’s not a easy access place to cut the fuel line and add one.  When did they switch to Linhai engines?  

I heard they switched to Linhai a few years ago after having bad luck with the Hisun engine.

[Ridge Runner]

Thank you.  I think the Coleman 550 Outfitters have Hisun engines

[Dennis Knepp]

On 4/13/2021 at 7:04 PM, cliffyk said:

It is most definitely a Linhai-550 then...

I wish Massimo (and others) would stop doing that--493 cc is at best a "500", stretching it to 550 in the model designation is a bit much. Years go I has a BSA 441 Victor. guess how many cc displacement it was?

Like that beezer, I had 1 thinkin it was green.