Slow Starting Speed on QSM11

[crplatt41]

Greetings,

 

I tried to submit this message earlier, but didn’t see the message posted. My port engine turns over much slower than my starboard engine during starting (engine battery was recently replaced). When cold starting, I have to connect the house battery in parallel. When starting a second time, I don’t have any issues and can start with just the engine battery and speed is higher.  the terminals look good from battery to starter. I’m thinking next step is to replace/rebuild starter, but was looking for help to confirm or steps to further isolate issue. I don’t want to depend on house battery to start this engine.

 

Thanks,

 

Clay

Topic

[Tony Athens]

You found your answer–Now find the weak/high resistance connection(s)  or cable. Many to check on the POS side. Less on the  POS side…..

If you had a 2/0 cable long enough, run it in parallel, direct  from BAT POS to the POS stater lug for a test.. Bypass the big switch, etc. But check all the NEG’s first.. All clean and shiny/tight and common lithium grease on all points of contact.

[crplatt41]

QSM11 Starting Test

Voltage Drop (V) Positive Battery to Starter Terminal:

Port Engine:                2.3 – 4.2*                 Engine start speed LOW, does not start

Starboard Engine:     1.6 – 3.1*                   Engine start speed OK, engine starts normal

I’m thinking your initial thoughts are confirmed with these results. Need to find the connection/component causing the higher drop in the port engine.

 

[Tony Athens]

Do both sides and compare.. I think it’s going to be obvious.    

[Tony Athens]

Hook it up as shown in the pic, key on,  and the VOM should  read  000 ,   Cranking the engine will measure VOLTAGE DROP which will be excessive.. 

WHY? Due to something not right in the  “big cables going from the start battery to the starter.. Could be a POS or NEG and at battery switch,  cable end, connection, etc. During cranking, something is probably getting hot to the touch. That will b the “bad part/connection”.

 

[crplatt41]

The distance is about 4-5 feet. I’ll measure the voltage drop.

 

Thanks,

 

Clay

[Tony Athens]

Again: What is the distance from the BIG POS post on the starter to the POS post on the battery in a straight line? I want you to make a test so this is what I want at this time–NOT cable length.  Do a own  decent digital VOM?

[crplatt41]

Hi Tony,

The batteries sit between the engines and are low in the bilge. I believe the cable will be a bit longer for the port motor due to the starter being outboard…I’ll have to measure the cable length. I’ll go ahead and clean up terminals and connections. Then, I’ll swap starters (both rotate same) to see if the problem moves with it.

Thanks,

Clay

 

[Tony Athens]

Sounds to me more like low voltage and low current flow to the starter during cranking due to a one or more high resistance connections somewhere in the starting circuit..

What is the distance from the BIG POS post on the starter to the POS post on the battery in a straight line?

[Author]

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