Spitfire Hard Starting?

[drdon]

After about a month of cleaning/rebuilding etc...the Spitfire is together. I could not resist taking for a run in the grass. I have only run the engine once before for a few minutes with a rigged up gravity feed fuel bottle. So after a few dozen pulls I got it running and she ran surprising well and fast (my 1st time on a sled). So here is the problem....It seems like it won't keep pulling fuel (pump) unless the rpms are up...go to idle and she dies. I have replaced all the fuel lines, filter and looked the pump and vacuum line over, no issues. The fuel lines are clear and once it stops there is air from the tank to filter...fuel from filter to pump..and then only half full from the pump to carb. When you pull start the fuel line out of the tank does not seem to pull fuel from the tank. The tank is about half full, I thought maybe the pickup was not int eh fuel, pulled it out and stuck it a bucket of fuel still does not want to pull the fuel. So it seems like the pump to me, but once i do get it running it will pull fuel, weird! Any thoughts or other things to try?

Here is a picture of my brother on the sled...gonna be a blast once the bugs are worked out!

[harleysportster]

Did you replace the ball check-valve on the end of the pick-up tube in the tank?

[drdon]

I thought that was just a screen. Is there a check valve inside? What would the purpose be?

[drdon]

I verified there is not a check in the tank screen.

Any other thoughts?

[Sprailfire340]

The check valve keeps the fuel in the line from draining back into the tank when not running. A primed line will start easier than a line with air pockets. You can pick up a new screen/check valve from the local JD shop as they still use it on the lawn and garden line.

[harleysportster]

If your local JD dealer doesn't have it, go to your local sled shop. They may stock it from Part's Unlimited.

[drdon]

Thanks for the help. I will most likely try in the check/screen and go ahead and rebuild the pump.

[SpitfireKing]

Not enough vacum from the motor when at idle???and chance of a crank seal leak boys?? Just throwing out other idea's

[harleysportster]

Low crankcase pressure / vacuum will cause similiar symtoms. As mentioned in other posts, with an unkown engine repair history of an engine, you should always replace the crank seals. I would also rebuild the fuel pump since the fuel pump diaphram arrangement has tiny valves covering the inlet/supply ports. As they wear, the function of the pump is dependant on the check-valve in the tank.

[JDT]

I am with the last two posts. Bad crank seals.

Also you may want to look at the rear springs on the suspension. Looks like it is very low in the photo you posted.

[drdon]

Thanks again, I guess I will try the tank check and pump rebuild 1st and see what happens. My understanding on the history of this motor/sled was the bearing (right side) went out at about 500 miles and the sled has sat behind the chicken coop (really) since. I actually bought it for the motor for a go-kart. Once I started tearing into it I figured why not fix it, I paid $75 for it and have about $200 in it so far. I hope it isn't the crank seals.

[drdon]

Oh yeah, I do have the rear springs set to the lower position.

[harleysportster]

Thanks again, I guess I will try the tank check and pump rebuild 1st and see what happens. My understanding on the history of this motor/sled was the bearing (right side) went out at about 500 miles and the sled has sat behind the chicken coop (really) since. I actually bought it for the motor for a go-kart. Once I started tearing into it I figured why not fix it, I paid $75 for it and have about $200 in it so far. I hope it isn't the crank seals.

The crank seals are not hard to replace . Check out the on-line service manual:
http://www.vintagesnow.com/John_Deere_f ... July79.pdf

[JDT]

Seal will only set you back $10.