electric fuel pump - power issues / grounding out?

[chris paddrik]

I've had a number of problems lately and everyone has been very helpful. So lets get to it:

1996 Stingray Mercrsier alpha one
Having problems with the fuel pump not coming on, tried everything i could find (ie jumping oil pressure switch, checking connections, checked correct voltage in the power supply, ect), nothing seemed to do the job. So detached the entire pump, cleaned the connections on the pump itself and bench tested it. I jumped it directly to th battery, and it worked! Connected it back up, and nothing. Pulled it back off, connected it directly to the battery again, and it started working again. while i had it connected it to the battery, and still running, i reached over to unhook it, and the copper hex bolt that connects to the fuel line to the carb touched the engine block and it sparked, and quit running.
So i did the same thing again, power dierctly to the pump, touched the hex bolt to the engine block (more speciffically, the exact metal fuel line that it is supposed to connect to) and it sparked, stopped running, then when i pull it away, it starts running again.
So, it seems to me that the pump is grounding out when is is hooked up the way is should be. because the pump works fine when uninstalled. I double checked and the key was out, and there was no power going to anythign but the pump.

1. am i right, is the pump grounding out?
2. is this a pump problem or a ground problem?

 

[Silvertip]

Re: electric fuel pump - power issues / grounding out?

Do you have the battery cables connected properly in the boat (e.g., not reversed). Sounds like you have a reverse polarity situation. Grounding the pump to the engine block should not cause a spark unless reversed polarity is the cause. When the pump is on the bench, the pump housing is not at ground potential so it would run -- but very likely backwards.