1985 745t

So, after reading numerous resources on the web I believe my Fuel Pressure Regulator is bad or I may have small leaks (that I can't see) on the intake manifold (at the hosing connections). Does anyone know if you can remove and repair the regulator? What's the best way to test for leaks at the hoe connections on the intake manifold?

Read on if you are interested in some background and data on this, it may prove interesting to other people who notice performance drops at high boost but whose vehicles run fine in normal circumstances.

BACKGROUND:

I recently replaced my sender/primary pump. After taking the car out it seemed to lose power slightly when flooring the accelerator and fully engaging the turbocharger. It felt like it wasn't getting enough gas, or something was holding it back slightly.

ANALYSIS:

I first thought I must have installed the sender assembly in a way that slightly interrupted the flow of fuel at the pre-pump nozle, or that the new hose design included with my new sender (they now use an accordian hose in place of the straight hose for the connection between the pre-pump and sender assembly, I imagine to reduce breakage of the hose with bending and age) was affecting fuel delivery to the main pump.

However, in researching the issue I came across numerous articles that discussed possible issues with the FPR on turbocharged vehicles. They discussed how the car can appear to be running optimally during idle and normal operations, but that "On acceleration under turbo boost, the car will lose power and may have black smoke coming out of the tailpipe." This seemed familiar, so I read on. Seems visually imperceptible intake air leaks under pressure between the turbo outlet and the engine can cause this to happen. Also, a fuel pressure regulator that sticks shut with pressure on the vacuum line from the intake manifold, increasing the pressure to the injectors to full pump pressure, which is near 100 psi, may cause it.

SOLUTION:

Haven't actually done the work yet, but I plan to test all connections on the intake manifold for small leaks. Additionally, I will probably just replace the FPR while I'm at it. I thought about installing a pressure gauge to actually see if it is malfunctioning, but since the FPR costs around $35 and the gauge sells for $20-$40 I figured I might as just replace it and not waste the same money testing it.

If you have any thoughts please post them, I'd love to hear the opinions of more accomplished and knowledgable volvo owners.

-Rick