The last 787 3d ??

[johna56]

Need a little help diagnosing a starting problem. Background - engine rebuilt professionally, exhaust repaired, new OSD heavy duty rectifier installed Feb 2020, new starter solenoid in spring 2019, new battery in fall 2019,, used mpem installed spring 2016. Machine was running great this summer. In august, relocated the battery to the rear of the machine. I extended the existing 6 gauge battery cables about 3.5 feet by splicing 4 gauge cable (this was suggested to lessen resistance over the added length of the cable) Machine was not run for about 6 weeks from start to finish (b/c vacation). After completion, the machine turns over and sounds good doing do, but will not start. Crossing the poles on the solenoid yields the same result. Battery was tested recently at a shop and I was advised it is good. When i checked the battery, voltage dropped to about 10.4 when i hit the start button. What are the steps and items I should be checking here? Thanks.

 

[mikidymac]

With voltage that low there is a good chance it will not spark.
My guess is the spliced cables is causing your voltage drop. To do it correctly you need a single piece of cable from the battery to the starter/solenoid with no splices and very good connections.

 

[johna56]

Damn, I bought enough cable to run them directly but the electronics store guy convinced me that was over kill. Ill pull off the splice sleeves and se if it jumps to life using the original cables. Would you think soldering would be good enough to connect the cables or likely not?

 

[mikidymac]

I wouldn't. Every splice and connection will allow corrosion and voltage loss.

 

[johna56]

Ok, thank for the advise. Im going to try to correct this weekend.

 

[johna56]

*advice.

 

[gazzaskirepair]

Pull the spark plugs to confirm you still have spark too
With the extended cables and plugs removed you should still see spark

 

[SabrToothSqrl]

So... why would one relocated a battery inside a working ski again..?

 

[AKnarrowback]

Not familiar at all with the 3d, but doesn't it have a 787?

On my 97 GTX there are two wires that land on the negative post, a large one and a small one. On my 787 I lost spark when the terminal of the small wire broke off. If you have two black wires to land on the battery did you extend the smaller one as well?

Just throwing that out there, correct me if I'm wrong.

 

[johna56]

Yes, its the 787 rfi engine. The original wires are all still attached properly, it does seem like the spark is very slow - a spark every second or so. If i rerun the power lead as one cable (no splicing), but keep the ground splices, would that act as a hindrance to starting? Thanks for all the responses. .

 

[johna56]

Update....... starting issue was the cables. I went back to the original cables and its starting no problem. A member on an electrical forum said I need 1 or 2 gauge cables for the that distance, and as mentioned here, - no splice. Thank you all.