bad fuel?

[dizdak]

so my truck was running decent as usual, front tank was really low so i was running on rear tank, stopped for fuel, swithced back to front tank... few miles up the road when i stopped i noticed the truck was smoking like a chimney at idle, and it was shaking the whole cab like a large cammed v8.. seems to run like it should at speeds, just at idle it has the problems...weird part also is that as it feels lopey and shaking the cab, my tach doesn't drop or anything like loosing rpms... could this hopefully be a symptom of some crappy fuel? timing is right..

 

[icanfixall]

Try adding fuel to the other tank but get the fuel from another station. If it run bad on the fuel in the other tankd from another station then I feel the pump is failing. How many miles are on the injection pump.

 

[dizdak]

probably only 5k max miles on baby moose IP and new bb injectors when pump was done.. I did switch back to the other tank, but only drove maybe 4 miles to the house... gonna go get fuel from my regular station tonight or tomorrow.. you say "the pump" do you mean IP or actual in tank fuel pump?

 

[IDIoit]

no pump in the fuel tank, i think he's talking about the lift pump on the pass side of the block

 

[dizdak]

ok thanks... is there only a single lift pump or one for each tank?

 

[IDIoit]

One single lift pump. On the engine
And a problematic valve on the frame rail by the front tank.

 

[snicklas]

If it is still the stock setup. It is a single mechanical pump, just like on the older carbed gassers. It is on the passenger side of the block, below the area of the fuel filter. The selecting of the supply/return tank and gauge is from the FSV (Fuel Selector Valve) on the drivers side frame rail, normally below the cab, forward of the midship tank.

 

[icanfixall]

Whats been posted is correct. All of our idi trucks have just a single lift pump mechanically bolted to the passenger side under the alternator and vacuum pump. With a baby moose pump I'm not thinking its bad. Do you find the truck runs out of fuel showing about 1/4 tank left. If so you probably have the broken off suction heads refered here as the shower heads. When the break sometimes they end up in the fuel tank switching valve and cause all kinds of fuel suction issues. Small pieces cause the valve not to completely change from tank to tank. Then air sucks in. When the lift pump fails it can fill the oil pan with diesel or just not pump fuel. Then the engine runs but very badly. Usually the fuel light comes on the dash telling you something is wrong. When the light is on its telling you there is no pressure feeding the injection pump. Our injection pumps do have a small suction screen and a pump to pull fuel but its not a good idea running on that. We need an electric or mechanical lift pump able to push fuel to the injection pump with about 7 lbs pressure.

 

[dizdak]

thanks guys, i will get to checking it out.. and yes my rear tank does run out at 1/4, and i have about half tank in there according to guage, so it does make sence that when i switched to the front tank again it may have pulled crap up into that FSV..can't stand to ole girl looking bad at a light smoking like that so i will chase the problem down!

 

[dizdak]

can i pull the FSV and clean it ? or do i have to replace it? cause i think that will be my starting point tomorrow

 

[snicklas]

You can pull it and try to clean it. Or use a lower pressure air, and blow back through it from the lift pump..... might give you and idea if it is plugged.

OLDBULL has a thread about tearing apart the FSV and cleaning it out.

 

[dizdak]

ok... i will give it a shot.. it seems to be smoking worse today and idling poorly

 

[dizdak]

well good news is nothing was wrong, pulled the FSV, ordered another one, parts strore got wrong one , so put the old one back in , (ford wants $389 for one), noticed the color of the fuel that was coming out,, well apparently i had a run of watery fuel.... also the rear tank that i was running off of the fuel in there was rather old.. drained both tanks, fresh diesel in, new fuel/ water seperator and she's good as a new 280k motor again lol... the fuel coming from the water seperator looked like rust water fuel... but she is back to running smooth and no smoke..but when i was smoking that bad i did notice i have a leak up at the down pipe so gotta get it sealed up better...

 

[opusd2]

Not to drag up an older thread, but what may be a good idea is to run some biocide through both tanks. If there was water in there, it doesn't take long for the sludge to start growing and building up. The stuff isn't cheap, but it's good to run it every now and then especially if there was moisture in the system for any length of time. That may have been some of the gunk you saw in the tank valve.

 

[dizdak]

thanks i will look into that..with the fresh fuel put some Dieselclean in both tanks... also fixed the rear pick up tube, or what was left of it, no maybe no more running out of fuel at a 1/4 tank..