This weekend I put a new lift/feed pump on my '91.
For almost 13 years now it has fired up within one second of hitting the starter even on cold mornings.
After I changed the pump I fired it up and it ran fine for about 20 minutes. I thought all was OK.
The next morning I went out and it wouldn't hit at all.
I cracked the injectors to bleed them and it hit, ran rough then smoothed out fine. Drove it to town. After sitting for about 30 minutes it was hard to start again. I put the pedal to the floor and it hit, ran rough then smoothed out. I drove it home...ran fine. Shut it down and immediately started it again. Started on first revolution. Let it sit about 30 min and again it was hard to start. So I cracked the low pressure bleed screw on the side of the filter housing and pumped the pump lever a few times trying to get all the air out. A few bubbles came out then pure fuel. Closed it back up. This helped but it still balks when it has sat for a while. I have to keep my foot on the pedal until it smooths out then it idles and runs normally.
What have I *$@#ed up????? Is there any other places that I could try to bleed air out of it?
Does the fuel system stay pressurized after the engine is shut down and if so could a small leak be letting the pressure leak down after it sits for a while leading to hard starting?
HELP!!!

 

On the older trucks, the return lines are rubber, and frequently crack when disturbed, (like when changing lift pumps )
When this happens, the system will loose prime after sitting for a few minutes.

Ed

 

Ah, so it does keep some pressure in the system when all the hardware is ok? That could be it.
When I try to restart within a few seconds of shutdown it hits right away. But when I let it sit it's hard to start.
I'll check and replace the rubber lines and make sure I don't have any leaks anywhere else.
Thanks

 

OK, I feel pretty dumb right now.


It turned out to be the clamp on the rubber line coming from the tank. The stock hose clamps are c**p! I had tightened it until it wouldn't turn anymore and it still didn't seal. So I went and got some new line (the old one wasn't cracked but....) and some good worm gear hose clamps and changed the line.
So far all is back to normal. Guess it was losing prime through the bad seal???

Thanks shovelhead

 

Cooool.
Glad it worked out.

Let's see,
Stock = Junk.......sounds about right.