Engine/Transmission (1998.5 - 2002) Boost problem

[jaybigboy34]

My truck has lost some boost pressure. It was reading between 40 and 42lbs. Now it is reading about 34. What could be the cause? I cleaned my air filter. My egt's are not any higher. Could my fuel filter to my fass system need to be changed? I don't have a fuel pressure gauge yet. It is in the near future. Does anyone have any idea?



Thanks

 

[Bob Wagner]

could be a combination of colder air and winter blend fuel.

 

[pro99]

I wouldn't overlook a blown head gasket. Mine did the same thing and it didn't show any coolant problems. The gasket blew into the rocker arm passage into the oil. I trashed my head gasket at 42lbs too when it was cold out!!

 

[rubberneck]

Intake manifold gasket or intercooler boot? I blew the intake manifold gasket out of mine and lost about8-10lb boost. FWIW, i did not see a significant increase in EGT, which seems odd to me. check it out. on mine, you could see a very distinct hunk of gasket pushed out right underneath the airhorn. Not too bad of a job, but all injector lines must come off. If it is blown, make sure the intake is nice and flat before putting a new gasket in. Also check the lower intercooler boots. they can be cut by the body. I had one that developed a hole and lost boost. If this is the culprit, take a pair of channel locks and roll the lip on the body away from the new boot.

 

[jaybigboy34]

Thanks for all of the replys guys. I changed my fuel filter on my fass system and cleaned the air/water separator and it seems like boost is back up to normal, which was around 41lbs. I need to invest in a fuel pressure gauge badly before I get stranded on the road somewhere.