help,fuel in the oil?

[imfixinmopars]

i just bought a 84 6.9.it seems to run good,but once in a while the truck acts like its running out of fuel.it will start to need more throttle and sooner than later it will want to die.if you let it sit for a few seconds,and restart the truck it runs strong.also the fresh oil looks real runny,like fuel in it,but really hasnt raised the level,this is in 50 miles or so,and the oil psi is at 20 hot idle and 42 on the run.i installed new fuel filter,new bypass line kit,new mech fuel pump.can you tell w/o removing the ip,if its leaking into the crankcase?the oil psi concerns me,since the factory guage was really low at hot idle,so i put a manual one one to get a true reading,help me guys,i kind of like the truck and want to keep it,thanks for any help

 

[Agnem]

How many miles are on the IP? Are the tanks full? Describe "once in a while". Can you correlate the problem to temperature or any other factors?

 

[imfixinmopars]

unknown miles on the ip,but it is stamped reman on the hsg.,and the motor appears to be rebuilt.the problem mostly happens about 5 miles away from home,but maybe 1 out of 6 times.the temp of motor is low,and outside is 40-60 degs.the front tank is 1/2 full and the rear is low.i ck out the tank switcher abd it works fine,it was out and i low psi ckd it both ways...im more concerned w/ the oil psi prob?..is 20 idle and 40-45 at 55 mph too low?a friend was by w/ his idi and i looked at his oil and seemed to be the same visc. as mine at simular temps.thanks for the reply and we are learning a lot from you guys about these trucks.i want to know the condition of the truck before i put more cash int o the truck. 2wd dually std cab 4 spd. decent condition,thanks mike

 

[stiesel]

i wouldn't worry about the oil pressure, the guages in these trucks in general just suck. that also might account for the low engine temp. i bet if you check the coolant temp the same way you checked the oil psi.(manually) you'd see the same kind discrepancy in the gauge. you may want to do a blackstone oil sample.

 

[riphip]

Your oil pressure is fine (I have one that is -10# at hot idle). Sounds like it may be your lift pump. If it gets too bad, it could pump fuel into the oil.

 

[norve8c9]

I had an old ford with a 360 and the fuel pump started pumping fuel into the block. It got bad enough at one point that their was gas bubbling out of the valve cover breather but was still running, cant beleive it didnt start on fire.

 

[Dave Sponaugle]

Sounds like a lift pump diaphram rupture to me.