E9-500 No Boost

[1951 Mack LJ]

I bought this 1987 Superliner with the E9-500 and drove it home over 300 miles.  It would barely run up to 1,400 rpm and little power above 1,000 rpm.  Thinking that since it had zero maintenance for what looked like a decade I was hoping it was going to be plugged fuel filters or old fuel lines.  After getting home I replaced the air filter, fuel filters, fuel lines from the tank, had the turbo rebuilt, checked for intercooler leaks, intake gasket leaks and fuel pressure after the lift pump was around 25 psi at idle.  But still zero boost.  Puff limiter was pulled before I bought the truck.  It idles smooth and runs up to 1,700 rpm but no power above about 1,000 rpm or so.  Has dual exhaust and doesn't seem like it is plugged.  I checked the fuel return check valve and everything looked intact. Even pinched the return line some with a c clamp incase the spring was weak in the return check valve.  What do I check now?

[BOBWhite]

Sounds like the pump to me, does it have the Ambac pump? I would check to see if the intercooler is internally plugged (check the pressure at both ends) then look over the whole turbo system again. If all checks out it might be time to get that pump off and get it checked. 

[1951 Mack LJ]

Yes the v style Ambac pump.  I pulled the boost tube after the intercooler and it was getting a ton of air pushed through from the turbo so I figured it wasn't blocked up with oil residue. I been thinking it was the pump for awhile but hoping I was missing something cheaper. The only pump shop within a few hours said they don't have parts to rebuild the pump. I also surfaced the exhaust manifolds and checked for cracks in the exhaust feeding the turbo.  Should I check for fuel pressure from the lift pump at full throttle and if so how many psi should it hold?

Edited August 5 by 1951 Mack LJ

[BOBWhite]

I've read about some E9 owners swapping the Ambac pump for an inline Bosch but it takes quite a bit of work (and $$). Not a pump expert but someone on here should have some answers. 

Edit: To test a CAC properly you have to check air PSI before and after it goes through the cooler.

Do you have the book for the E9? I can PM it to you if you need it. 

 

Edited August 5 by BOBWhite

[fjh]

9 hours ago, 1951 Mack LJ said:

Yes the v style Ambac pump.  I pulled the boost tube after the intercooler and it was getting a ton of air pushed through from the turbo so I figured it wasn't blocked up with oil residue. I been thinking it was the pump for awhile but hoping I was missing something cheaper. The only pump shop within a few hours said they don't have parts to rebuild the pump. I also surfaced the exhaust manifolds and checked for cracks in the exhaust feeding the turbo.  Should I check for fuel pressure from the lift pump at full throttle and if so how many psi should it hold?

 Two simple things Check the throttle lever is going to its full stroke check the stop for full on! If you have a boost leak it should be laying down a fare amount of  gray / black smoke travelling along the road! air filter clean ?

[Joseph Cummings]

Hook a gauge up where the fuel line goes into the pump, and take it for a run to see what the fuel pressure is doing. If you don't do that, you are just firing the parts cannon