No power at idle

[fpchief]

I know I need to turn the android, however the plug I have to remove is not wanting to budge. Dang near stripped it today. I have it soaking in PB right now. besides that I am asking if there is anything else I can do to help my problem. The truck has zero...I mean no power if there is any bind on the tires at startup especially on a cold engine. An example is I park in soft gravel and this afternoon I put it in gear and it would not move. In reverse is not a problem. Have had it shut down on me a couple of times when trying to start from a stop and turning at same time. This is a problem and I have to fix it. Otherwise it runs excellent and has excellent mid and top end.

 

[74M35A2]

No androids.

Sounds like air in the fuel, or weak fuel lift pump.

Replace the filters, make sure all seated correctly, replace soft lines on the suction side, then test fuel pressure after the lift pump. This will also tell you if the overflow valve in the injection pump is OK. Install a clear piece of hose on the return, look for bubbles with engine running, suspect tank pickup tube or solder joint at dip tube top.

The 8.3L has very weak low end, but stalling indicates an issue. Reverse is 10:1, vs 1st gear 4:1, so that is why it feels like that.

 

[fpchief]

Dang auto-correct....aneroid....brand new filters (I have the small inline along with engine mounted filter). I have noticed a small dampening of fuel on top of tank. Great advice. Thank you.

 

[simp5782]

Dang auto-correct....aneroid....brand new filters (I have the small inline along with engine mounted filter). I have noticed a small dampening of fuel on top of tank. Great advice. Thank you.

The inline is collapsed. Cause it's not the diesel specifically inline i bet

 

[74M35A2]

Dang auto-correct....aneroid....brand new filters (I have the small inline along with engine mounted filter). I have noticed a small dampening of fuel on top of tank. Great advice. Thank you.

You could try a small outboard motor fuel tank to help diagnose. Connect that to lift pump, if runs good then problem is before lift pump.

 

[fpchief]

The inline is collapsed. Cause it's not the diesel specifically inline i bet

It is the part number on your spreadsheet. I think from oreilly

 

[simp5782]

It is the part number on your spreadsheet. I think from oreilly

33972 is only 1gpm max flow

 

[fpchief]

One I have is the metal one. ...3270. They first tried to give me that plastic one.

 

[fpchief]

Is the top of the lift pump where the transducer goes in the best place to put a gauge? Looking for easy and quick for troubleshooting. and hopefully parts I can find in my small town. Will toss the transducer too.

 

[74M35A2]

Is the top of the lift pump where the transducer goes in the best place to put a gauge? Looking for easy and quick for troubleshooting. and hopefully parts I can find in my small town. Will toss the transducer too.

Yep. Sounds like you’ve done decent homework, thanks. You could probably even drill out the center of the transducer you are removing and tap it for pipe thread then add gauge and hose? I have never had one in my hand to see, but that is what I would try.

 

[fpchief]

Gotcha. Got an old gauge I use on the deuce and so forth I will try and plumb into it. will report back with findings.

 

[74M35A2]

Gotcha. Got an old gauge I use on the deuce and so forth I will try and plumb into it. will report back with findings.

If little to no pressure, pinch the return line closed which exits near the front of the injection pump. If pressure increases, the lift pump is maybe OK and the overflow valve in the injection pump is then suspect, which is just a simple spring loaded check ball integrated into the banjo fitting bolt of the return line fitting at the pump. It can be cleaned in the field by blocking off this line for 30 seconds at a time at idle, then release, and repeat. When you use the primer button on the lift pump, and the system is free of air, you should hear this relief valve “squeak” with each push of the primer plunger button, as it unseats and allows surplus fuel to flow past it.

 

[fpchief]

I have the squeak....pressure shows about 25lbs at idle. Put in gear and I believe it is still around 25 lbs... needs a snubber since bouncing pretty bad.

 

[74M35A2]

I have the squeak....pressure shows about 25lbs at idle. Put in gear and I believe it is still around 25 lbs... needs a snubber since bouncing pretty bad.

That seems good. I’d next still check for air bubbles in the return line by using a piece of clear tube along any part of it. Pain in the butt, but excellent diagnostic tool. Aerated fuel from a suction leak will do exactly as you are describing.

 

[fpchief]

This may be stupid question...are you talking about cutting and splicing?

 

[74M35A2]

This may be stupid question...are you talking about cutting and splicing?

Could, but I would just have a hydraulic hose place make one up to add to or replace an existing one. There is zero pressure on it, so just clear tube with the correct fittings on each end. Or short piece with fittings to add into an existing connection.

 

[74M35A2]

Maybe I’ll make 100 of these and sell them. Buddy works at a hydro shop very close to my house. Yeah, I’m doing it. If you want to wait until Monday, I’ll have the first one down. Test it and you can have it for free.

 

[74M35A2]

Maybe I’ll make 100 of these and sell them. Buddy works at a hydro shop very close to my house. Yeah, I’m doing it. If you want to wait until Monday, I’ll have the first one down. Test it and you can have it for free.

I forgot if the 8.3L MW pump is boost referenced, it should be. Make sure this pressure line is clear, connected correctly, and could check the diaphragm, spring, and internal movements associated with it.

 

[fpchief]

Maybe I’ll make 100 of these and sell them. Buddy works at a hydro shop very close to my house. Yeah, I’m doing it. If you want to wait until Monday, I’ll have the first one down. Test it and you can have it for free.

I pay

 

[74M35A2]

I pay

I’m making the first proto tomorrow, can ship out Monday. Will install at fuel tank return line connection to cover entire system, and work for all M939’s.