Hard starting when hot...Or not?

[snatchal]

My truck always starts great when it is cold. But, for about the last month it sometimes takes a lot of grinding to get it to start once it is warm. I mean grind and grind until the batteries are almost dead, say a prayer, cuss, wait a while, and then it finally fires up.
So I searched though some old threads and came up with the conclusion that my injector pump is about ready to puke. Fine, I'll buy a new one.
Now here is where it gets weird. I have about a hundred gallons of 35 year old fuel oil that I got for free last summer. Last week, after the price of fuel hit $3.00 a gallon, I pumped about 15 gallons of this crap into my tank along with 5 gallons of waste motor oil. Now it still starts fine, maybe just a bit more smoke until it gets warm. But now no more hard starts when it is hot! The motor also sounds stronger and my truck seems to have more power. So do I replace the IP or keep using garbage fuel???

 

[CRMW]

Use up the motor oil and old fuel with your current Injection Pump (so what if it gets screwed up) and use the money you saved to buy a new pump.

Chris

 

[Diesel JD]

Yeah use up the junk fuel and see what happens. Probably it lubes the head a little better and it doesn't swell up like it does on ULSD. Use the junk fuel till its gone, then when you go back to ULSD and then O/D it with Power Service or Stanadyne lubricity. Still be ready to replace it...it might be ready to die. Keep a little lukewarm water in the truck and if you have more problems with the IP dump it over the IP head, and see what happens.

 

[Agnem]

Sounds like heat soak for sure. The reason it starts after lots of cranking, is your passing cooler fuel through the IP and out the return which eventually shrinks the pump enough for it to start. Dumping 12 oz of room temp water on it will work a lot faster. You junk fuel probably has a higher viscosity.