Suzuki DF300 HP Pump internal wire harness fault

[George pl]

Hello everyone, first post here. I would appreciate any feedback on a problem I experienced with my 2018 model year DF 300, bought new as a re-power. It has served me well with no issues till now, having done around 110 hours since new. A month ago, at the end of a day out fishing, the motor would turn but not start. Only 5 miles out, I limped back to port under kicker power. Fast forward some diagnostics, the HP fuel pump appeared to be at fault, with open circuit measured externally on the VST HP pump wire connector. To my surprise though, when the VST was stripped open and the fuel pump removed, it was apparently normal, measuring 0.7 Ohms coil resistance as per specs, and running smoothly and silently (for intentionally short periods ) with the bench DC power supply. Instead the problem was traced to the short wire harness connecting the HP pump internally to the connector on the VST case. Specifically the connector on the VST side was partially melted and one contact inside burned. There was some soot on the male contact on the VST case connector as well. Otherwise, the inside of the VST bowl was pristine, no dirt or evidence of water contamination whatsoever. The boat does have a Racor water trap installed.20230713_163019_resized.jpgVST STRIP.jpg20230713_172324_resized.jpg20230714_162626_resized.jpg

My initial joy at the prospect of a cheap fix was quickly dampened, as Suzuki will only sell the HP pump and wire harness as a bundle.

With everything working again I cannot find anywhere any mention of this fault developing, with an apparently healthy pump. Just to note , the replacement, genuine pump measured and behaved exactly the same like the one removed from motor.

The DF 175 on my previous boat served me fine for 12 years and 850 hours, never missing a beat, so this is a surprise. I guess it could be a simple case of a substandard connector from the factory, but would appreciate any thoughts or suggestions as to the possible cause and ways to prevent a re occurrence.

Thanks in advance

[Moonlighter]

Not seen that reported here before.

So you’re sayingbthat the pump is dine, its just the connector that has failed?

I have bought various connectors for my outboards from Eastern Beaver Motorcycle parts in Japan, most of these connectors are not specific to Suzuki or to outboards - here is a link that you might look at to see if you can find the same connector and possibly be able to fit a replacement?

https://www.easternbeaver.com/Main/E...onnectors.html

[George pl]

Thank you Moonlighter, great link! Mind you, one is also anxious about using the wrong kind of cable to make a DIY harness, given this is immersed in petrol, even if you found the right connectors.

Yes the pump is fine, draws normal current when tested. It looked as if there was poor contact / arcing at the contacts because of the soot and molten plastic (grey connector picture) , but why? Could this be a kickback issue?

Anyway, quite scary to see this inside your VST petrol tank.

[boscoe99]

Not abnormal or unheard of. Appears to be a poor connection that leads to a temperature build up on the connector terminal pins. This generally happens due to corrosion.

It takes a certain air/fuel ratio for ignition to occur. Much too rich within a VST for that to happen.

New connector terminals, and or wires if needed, and you will be well on your way.

[George pl]

@ Boscoe99. Thanks for your thoughts, but " Not abnormal" ? ! Not sure I follow you. Given there was no sign of corrosion or water contamination anywhere in an otherwise pristine VST or engine in general, I think it was certainly not normal and points to a defect in the connector and/ or crimping process at the factory. Remember, this is a practically new engine with 110 hours. Sadly Suzuki warranty cover in Greece is 1 year only. Furthermore, if it is something that does tend to occur every now and again, then Suzuki should make the HP pump internal harness available as a stand-alone spare ( for $10-20 -30 ?) rather than saddle you also with a $ 500 HP pump you don't need. Steam off, rant over !!