Engine/Transmission (1994 - 1998) Fuel blowby question?????

[JoeyJ]

Noticed that every now and then I'll get a steady drip of fuel out of the blowby tube at idle. Should I be concerned? what is the cause of this?

Thanks

Joey

 

[TRCM]

fuel. . yes I'd be concerned. . oil... pretty much normal

 

[Signal73]

We are talking about the crankcase blowby tube, not confusing it with the smaller tube dangling in that location which is the fuel/water seperator drain tube? Fuel out the blowby tube isnt cool thats for sure

 

[JoeyJ]

It is fuel and it is coming from the blowby tube not the fuel/water tube.



Doesn't do it all the time but when it does... it does.



What might be causing this?

I DO NOT want to let this go on for long... . thanks.

 

[TRCM]

I'd send an oil sample out immediately and have it rushed. The only way for fuel to come out the crankcase blow off tube is if you have excess fuel in the crankcase. And that is very bad.



Are you SURE it is coming from inside the tube, and not running down the outside ?? You may have a fuel leak and it is spraying or dripping on to the blow off tube and it just looks like it is coming from inside the engine.

 

[bmoeller]

I'd check for a leak on the fuel injection pump. It is in the same area. Look at the return line that is on the pump, between the pump and block. Either a hole or bad washers on the overflow valve banjo fitting.



If fuel is actually coming OUT of the tube, stop driving the truck, 'til the problem is figured out and repaired.

 

[JoeyJ]

Thanks everyone.

I've determined that it only does it after a run at highway speeds. I'm leaning towards a fuel leak blowing on to the blowby tube. At times I get oil and fuel out/off of the tube but they are not mixed, separate drips. It's about time for a fuel filter and I'm adding a fuel pressure gauge so I've got to get into that area anyway. I'll let you guys know what I find.

Man I love this site.

Thanks again

 

[JoeyJ]

OK, so I finally got a good nights sleep last night, lol.

The fuel is not coming out of the blowby tube but running down the block, off of the oil pan flange and down the tube.

Still learning the CDIs, so bear with me.

It is leaking from, it it were a gas motor, I'd say was a mechanical fuel pump. Same type of look.

What is this?

Is it easy enough to remove and replace with a new gasket?

I'll try to tighten first if someone knows the torque spec.

Thanks

 

[TRCM]

sounds like you need a new lift pump. i am replacing mine tonight because it isn't holding prime.



I know it isn't the fuel line, because if it was a leak in the fuel line, it would have to be big enough for fuel to come out. I say this because my fuel pressure drops from 28 psi to 0 psi in less than 15 sec when the engine is shut off. That tells me the check valves in the lift pump are not holding. If the fuel line was leaking that bad, I'd see fuel somewhere.



The gasket look just like a SBC or sb chrysler gasket.



My lift pump was 118 at the local diesel shop.

 

[Signal73]

Maybe just the o ring on the primer button. Mine leaks when I prime with the button. Heard that thats the only rebuildable part on the pump so check it out.

 

[TRCM]

That's why I got a new one, but after talking to a friend who is very knowledgable, I am gonna return the one I bought. Most likely don't need it.

 

[TRCM]

Well, as an update:



Yesterday during a 90 mile trip, my fuel press dropped from a normal of 25 @ 65 mph, to as low as 14. I got where I was going, and checked the prefilter (suspected possibly a bad batch of fuel). It was clean as a whistle.



Got back home, and pressurized the fuel system with 10 psi shop air, and checked for leaks. Couldn't feel any anywhere. So, I took some water & dish soap and made a soapy mixture, which I then sprayed on everything to see if I got any bubbles from a small leak. NADA.



So I put the new lift pump on, and dissected the old one. Ain't much to them there suckas that's for sure. Didn't really see anything for sure wrong.



While I was under there, I noticed the boot for my fuel solenoid was bad, and the heim joint at the end of the solenoid linkage was stuck, and the cotter pin was gone, so that the solenoid could come off the lever. Took that off and repaired/rebuilt it, and made a new boot out of some old inner tube material.



Started it up, and FP was back up to 30 psi @ idle (OFV is shimmed). Removed the shim from the OFV, and now FP is 24 psi @ idle.



Took the truck for a test drive, seems to be doing good. Consistent 20-24 psi FP during most driving, and only drops below 20 psi momentarily during hard acceleration, then climbs back up.



Have to see how she does on the highway today.



BTW... it IS possible to replace the lift pump without removing anything else, but it is a PITA and your arms will hate you the next day.



And whose bright idea was it to sandwich the prefilter/heater housing between the lift pump and the block ???? Getting gaskets in there was a PITA and cost me an hour of time. Good thing I had extra small block chrysler gasser fuel pump gaskets (same gasket BTW), as the new lift pump only came with one gasket, and you need two for this job. I put the prefilter/heater assembly on using the bolts and some washers to let the gasket stuff (light film) set before I removed the bolts to put the lift pump on. That was when I found & fixed the fuel solenoid. I also used a longer bolt from the bolt bin to pull the lift pump on (compress the pump part) until I could get the correct bolts in.



And priming the truck is a bunch easier when you pressurize the tank with 10 psi... you just crack a fitting on top of the fuel strainer, and VOILA !... it's primed and she starts right away.



The bad part, is I will have to do some of this again this week, as I had planned on replacing ALL of the fuel lines, but had yet to buy the line... . so now, I get to do that as a seperate job, instead of all in one shot.