# Fuel system not staying primed-Tohatsu TLDI 40



## jmrodandgun (Sep 20, 2013)

Check your fuel tank vent. Rule that out first.


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## Guest (Aug 5, 2018)

I would suspect it is either pulling air or your new primer bulb is allowing fuel to backflow out of the engine.


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## CedarCreek (Nov 23, 2012)

jmrodandgun said:


> Check your fuel tank vent. Rule that out first.


Well, there was some fuel in the tank vent line so I got that cleared out. Maybe thats all it was. thanks for the reminder to check that.


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## CedarCreek (Nov 23, 2012)

Boatbrains said:


> I would suspect it is either pulling air or your new primer bulb is allowing fuel to backflow out of the engine.


The problem started before i replaced the primer bulb. Hopefully its just the vent being blocked but if not maybe a small leak or clogged filter??


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## Guest (Aug 5, 2018)

Your description sounds like air or bleed back to me. I doubt you have a blockage. If the vent was plugged it would most likely pull the ball flat from vacuum and then run out of fuel and die. JMHO.


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## weldandglass (Sep 29, 2009)

The TLDI engines have a documented problem with this (it's vapor lock), particularly during hot running conditions. I had a TLDI that did this frequently. I figured out that the solution was to pop the cowling and pump the primer ball, then open the shrader valve on the fuel side of the air/fuel rail with a screw driver or pocket knife and turn the key to on position so the high pressure fuel pump would spin and push the air out of the fuel side of the fuel rail. Once a clean fuel stream was coming out of the fuel rail the engine would start. I love the TLDI engines and I don't think they can be beat for power to weight ratios but this problem is a bit of a pain. The dealers recommend installing an auxiliary, external fuel pump near the tank. The pump gets wired to the engine so that when the engine is keyed on or running the external fuel pump runs and keeps the system primed. If you call a Tohatsu dealership that works on a lot of TLDIs they should be able to recommend a part number for the external fuel pump. I had the number on my phone but I lost it. 

You could have something else going on but I would bet that this is your problem.


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## DONAGHUE (Nov 18, 2017)

I had a similar problem with one of my skiffs ,not the tldi but a yams.... ended up being a collapsed fuel line at a 90 degree bend or bend from tank out front bulkhead down gunnal wall and back hatch to filter housing.... I could pull fuel from tank to motor via primer bulb no problem but the kinks were to much for the pulse fuel pump to prime.... easy fix if that's the problem ....


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## CedarCreek (Nov 23, 2012)

weldandglass said:


> The TLDI engines have a documented problem with this (it's vapor lock), particularly during hot running conditions. I had a TLDI that did this frequently. I figured out that the solution was to pop the cowling and pump the primer ball, then open the shrader valve on the fuel side of the air/fuel rail with a screw driver or pocket knife and turn the key to on position so the high pressure fuel pump would spin and push the air out of the fuel side of the fuel rail. Once a clean fuel stream was coming out of the fuel rail the engine would start. I love the TLDI engines and I don't think they can be beat for power to weight ratios but this problem is a bit of a pain. The dealers recommend installing an auxiliary, external fuel pump near the tank. The pump gets wired to the engine so that when the engine is keyed on or running the external fuel pump runs and keeps the system primed. If you call a Tohatsu dealership that works on a lot of TLDIs they should be able to recommend a part number for the external fuel pump. I had the number on my phone but I lost it.
> 
> You could have something else going on but I would bet that this is your problem.


I had read about this issue back when I bought mine in 2013. However, this is the first summer I have experienced this problem. I’ll talk to my service dealer this week and see if they’re familiar with this. Thanks


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## CedarCreek (Nov 23, 2012)

No resolution yet. Waiting to hear back when the service guys can take a look. Meanwhile, i was wondering if the vapor lock issue mentioned above or the fuel in the tank vent line caused the problem, would either of those cause a fault to show up for the fuel feed pump on the diagnostics? When i put the key in the start position i can hear the fuel pump run, however, one of the fault codes shows a faulty FFP.


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## makin moves (Mar 20, 2010)

100% vapor lock issue. I had same motor same issues. The send out computer to reprogram and they add another external fuel pump by the tank. Great motor but very very common problem. Sometimes you can pump the ball, start the motor and keep pumping ball until she catches. Doesn't always work. I played hell getting all of that sorted out as I was one of the first with the issue. Tohatsu knows exactly what the problem is so keep on them.


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## Guest (Aug 10, 2018)

One thing you can try.... If it is indeed heat soak, after a run allow the motor to idle several “3-5” minutes before shutting down. An engines temp will rise after shutting down in turn boiling the fuel out of the system causing vapor lock. The idle time allows the motor’s temp to stabilize before shutdown.


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## makin moves (Mar 20, 2010)

I wo


Boatbrains said:


> One thing you can try.... If it is indeed heat soak, after a run allow the motor to idle several “3-5” minutes before shitting down. An engines temp will rise after shutting down in turn boiling the fuel out of the system causing vapor lock. The idle time allows the motor’s temp to stabilize before shutdown.


 I would do that too and still didn't help. You could even have the motor shut off for 30 mins plus and would still happen. Once they made the changes I never had the problem. I loved that motor power for days , no smoke and good on oil and gas.


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## CedarCreek (Nov 23, 2012)

So, I ran it hard today in 90 plus degree heat. Stopping and starting numerous times. Not a single problem until the very end of the day when it started acting up. I said to myself it’ll start just fine back in the driveway when I get home once it cools down. Sure enough fired right up. I had very similar issues when I got it serviced 3 years ago. They changed the impeller, fuel filter, and plugs. Ran for 3 years Without incident. I’ll probably do the impeller and fuel filter myself just for routine maintenance and call Tohatsu about the vapor lock fix. Thanks


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## makin moves (Mar 20, 2010)

You can rack your brain and go through a million fixes but in the end its vapor lock. I chased this problem for months! Trying to get the dealer to believe me was no fun. It doesn't happen every time the motor is hot however it will only happen when motor is hot. The dealer would take it and try to replicate the problem with No luck. I finally more or less had to give him my boat and tell him use it like its your own, take it fishing , go cruising, shut it off fish for awhile and you will find the problem. Sure enough he did. They will fix it! Good luck.


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## CedarCreek (Nov 23, 2012)

makin moves said:


> You can rack your brain and go through a million fixes but in the end its vapor lock. I chased this problem for months! Trying to get the dealer to believe me was no fun. It doesn't happen every time the motor is hot however it will only happen when motor is hot. The dealer would take it and try to replicate the problem with No luck. I finally more or less had to give him my boat and tell him use it like its your own, take it fishing , go cruising, shut it off fish for awhile and you will find the problem. Sure enough he did. They will fix it! Good luck.


I hear ya. I don’t suppose the fix had a part or kit number? Also, what year was your motor? I thought the problems were prior to 2013. Guess not. Fortunately I can visit my service guy on the way home from work. It’s a PITA to replicate. I tried all day then at the ramp it decided to show up...


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## makin moves (Mar 20, 2010)

I would say mine was around a 2011. Over the years there has been several guys on here with same problems and I let them know my situation. They all turned out the same problem. It is more of a issue down south because of warmer temps. Wasn't just a external fuel pump need they also sent out the computer to Texas I believe. It is frustrating because it's not easy to replicate.


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## makin moves (Mar 20, 2010)

If I shut down and fired it right back up it was fine. It was when I would shut it off and fish for a while that I would have the problem.


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## CedarCreek (Nov 23, 2012)

Thought I would provide an update. So, I replaced the impeller, changed plugs, new fuel filter (low pressure), new fuel/water separator, cleared maintenance codes, and got the fuel out of the vent line. Been running like new so far even in the blazing hot weather. Pretty sure the lack of pressure in the primer bulb was due to the fuel in the sagging vent line (they're not supposed to sag are they?). I think the intermittent engine issues were due to a worn out impeller. That was the issue 3 years ago too. Need to replace that more often. I am in no way calling it mission accomplished though given the potential for the vapor lock issue that others have reported, but since i have not had that issue in the previous 5 years i've had the motor I am hoping its not the problem. We'll see...


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