hard start....HELP......

[Sootscooter]

I just put a n ew (old ) motor in my truck....It starts and idles great, But if I shut it off after the truck has warmed up, it will not restart. In order to restart it, I gotta run a jumper from the positive post on the battery to the top connection (s/s solonoid) on the pump.... Any advice? Thanks-Ryan

truck is a 90 f250 with a 1991 motor in it.....

 

[Mr_Roboto]

I'm not sure what "top connection" is.

I'm going to take a wild guess and say that once warm, you are losing a ground connection. Does the motor crank and not start, or not crank?

Often during engine swaps, the ground connection between the engine and body is left off or not connected properly.

 

[geonc]

Yup, follow the grounds first

as to why it will start cold ----GP draw etc.. yet not fire when at operating temps....pos inj pump heading south?
Are your lights/dash/acc all bright or do they dull when the eng returns to idle?

Double check all connections from the batts foreward and a liberal coat of dilectric grease at the connections won't hurt either

Get some seafoam or Stanadyne fuel treatment-----fill a new filter with one can and split the second between tanks.

"Could" be a "lubricity" issue with the IP

 

[Sootscooter]

when I try to start the motor after I have shut it down (warm), the starter motor will just crank. In order to get around this, I am jumping the s/s solonoid (I think) to the posive side of the battery (not negative as I previously posted). After I do this, It fires right up. Sorry for the confusion.

 

[Dsl_Dog_Treat]

I take it the engine is up to operating temp?
If so along with checking all electrical connections, try the bag of ice over the IP trick, could be signs of an IP going south.
Was the IP transferred along with the donor motor, or are you using the one off the previous motor?