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Discussion Starter · #1 · (Edited)
Hi, we have a bike shop and currently having immense trouble with a King Quad 400 Fsi. The bike starts fine, runs for a few minutes, then dies. The fuel pump gets extremely hot and you can hear it starting to struggle. There is definite pressure build up. We have replaced the fuel pump, still the same problem. We removed the fuel pressure regulator, cleaned it, but still the same problem.
Checked the fuel cap, no airlock.
Checked the spark.
For some reason the fuel pump is being put under extreme pressure and getting hot but we don't know why. The bike starts fine after it has died. PLEASE HELP
 

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2019 LT-A400F
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How are the lines going to the injector? The injector itself? This is something that I am curious about as I have a 2019 400 FSi. I am assuming the injector is electronic so possibly check resistance at the injector and the actual flow of the injector iteslf? Perhaps the injector itself is the restriction causing issues.
 

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Okay got home and started checking my service manual - the resistance across the injector should be 10-11 ohms at 24c temp. The injector should be getting full battery voltage when being activated. The fuel pump discharge amount should be 84mL per 10 seconds and the fuel pressure regulator should be set at approximately 42 psi/294 kPa. This is from my 2019 LT-A400F LT-F400F service manual so hopefully this will help you some!

D
 

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Discussion Starter · #4 ·
How are the lines going to the injector? The injector itself? This is something that I am curious about as I have a 2019 400 FSi. I am assuming the injector is electronic so possibly check resistance at the injector and the actual flow of the injector iteslf? Perhaps the injector itself is the restriction causing issues.
We ultra sonic cleaned the injector. So it doesn't look like that was the problem. We installed a second fan to blow on the air cooler. So far the bike runs without the the fuel pump heating up.
 

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I don't think you should need to install a second fan to keep it running. :( thats just addressing the symptom and not fixing it.

If it were me, I'd still be looking at the injector plumbing/feed lines for a restriction. Also I'd check the voltage going to the pump as well.

good luck!
 

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Discussion Starter · #6 ·
I don't think you should need to install a second fan to keep it running. :( thats just addressing the symptom and not fixing it.

If it were me, I'd still be looking at the injector plumbing/feed lines for a restriction. Also I'd check the voltage going to the pump as well.

good luck!
Hey, we replaced the fuel pump, cleaned the injector, cleaned the pressure regulator and checked for restrictions in all the feed lines.
I think the problem is that this quad is used to pull 350kg weight, at 5km/hr in 40°C heat for about 6hrs a day. It's bound to overheat.
 

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Hey, we replaced the fuel pump, cleaned the injector, cleaned the pressure regulator and checked for restrictions in all the feed lines.
I think the problem is that this quad is used to pull 350kg weight, at 5km/hr in 40°C heat for about 6hrs a day. It's bound to overheat.
Yes . Probably better off with a liquid cooled KQ 500 or 750
 
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