Hey guys,
I'm am having some concerns with my truck and running up a steep grade (unloaded in about 100F weather). Over the summer I drove my truck up in the northern part of Arizona to go camping and fishing, and the grades through there are about 6% or so. It seems that I have to get a running start on a down grade in order to have the momentum to get up the next grade. My truck is fairly stock with a small turn on the full power screw, a denny stage II, a 3200 spring, and it was having trouble keeping 60 mph up the grades with the AC off. I have had to down shift in order to keep the rpms up, and in doing so my water temp starts to climb a small amount with my EGT's at about 900 with about 8-12 lbs of boost. It seems to me that something is wrong when some trucks with 35' fivers are fling past me.

I have talked to some buddys about this, and I am hoping to get some ideas of what I need to look for. Also my oil, filter, and coolant was done before my trip, and I am thinking it is lack of fuel pressure.

Any thoughts would be great (sorry for the long read)

 

Is your clutch Slipping?

 

with an upgraded 14cm housing and the fueling mods you have ... your boost seems low - leaks?

 

Fuel pressure sounds right to me. I would assume that you have tried a new fuel filter? I don't remember you having a pressure gauge in your truck. I think I've got an extra you could barrow til you find the problem. Will try and make it to the next meet at the povilions and bring it for you. If you think you could use it?

 

Yeah I thought about that, what should it be at? I did not have my foot to the floor, due to temps. I'm wondering if the waste gate is opening?? If there is a leak what is the best way to find it?

I sure hope not, the clutch is no more that 20K old.

How much pressure should a stock carter lift pump be running?

 

I was thinking in the low 20s ... but that's just a guess, what's your normal max boost at?

You could always temp wire the W/G shut to see if that helps to see if the W/G is bad.

Normally to look for a pressure loss I would spray soapy water all over the components however you're going to need a load to build some boost ...

A proper way to do it would be to cap both ends of the I/C Tubes, pressurize the system then spray with water. (Or at least one end). I bet the local hardware store would have a 3" cap you could tap with a 1/4" barb to 1/4" NPT tap (JB welded into the cap ... with the pressure turned down to around 20psi ... that could work.

I've also heard of a smoke test, where you pump smoke through the engine looking for it to come out somewhere. Obviously the key here is to ensure you don't smoke the whole engine compartment out ... hehe

 

Yeah I think I am just going to get one because it is a good gauge to have and everyone can use another gauge. Do you have one hooked up, if so what does it run at and what does it pull down to?

This was another possibility that the wastegate is opening or it is bad. My max boost and I would have to be getting on it pretty hard is about 30lbs and it never sees it that high.

Question for everyone, let me know what your stock diaphragm lift pump runs at pressure wise, mine is very new and it says 5-7lbs but I am not sure.

Thanks guys for the help and any other ideas let me know.

 

Stock lift pump no more than 5-6 psi probably.

with your mods, probably like 0 psi at WOT

definely upgrade to a piston pump. it's not hard at all took me like an hour to get it on

 

Weld that WG shut!

I recently drove back from WV on 68, where there are some nice 8% grade hills. When I was going up them, running ~80MPH, I was seeing about 25 PSI and 1000 EGT and the truck wanted to go faster.

Something definitely seems stinky in Denmark!

 

Yeah that is what I have been hearing I just don't want to stave the VE of fuel. Would there be a benefit to getting an Airdog system would there? What does a piston pump run at pressure wise?

Also I have a 90* elbow that has a srew to shut off boost getting to the WG and as far as I can tell it is all the way(closed)

 

if you,re not running out of fuel you need to push more air. i run around 30 psi up simular grades at 6000 ft. elevation. if i hold around 30 psi boost with 7 blade hx 35/ 12cm i can tow 12k at 65 mph. i tested a 14 cm housing and a 12 cm in same conditions and the 12 felt stronger, egts the same. the he 351 will cool up to around 40 psi towing. i suspect as mentioned above a fuel supply problem.