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Discussion Starter · #1 ·
I have a '94 850 coupe that suddenly stopped running. Spark looks good, timing belt good, cap and rotor good, --> problem seems to be fuel.<p>How does one generally hook up a fuel pressure gauge on this car? I have such a European gauge for use with Bosch systems, as well as the adaptors, but don't see anywhere it can easily be inserted. There is a schrader valve at the end of the fuel rail but it doesn't seem to have a metric thread.<p>Symptoms: if I pinch the return line from the fuel pressure regulator, the engine almost catches, you can here a little firing and it cranks faster. If I bleed the schrader valve, I only get like a weak one-second squirt - doesn't subjectively feel like there's 3 - 5 bar there. If I clamp the return line, the squirt is a little better but still not much.<p>So how does one measure the pressure?<p>Cheers,<p>Kevin
 

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Re: 94 850 - measuring fuel pressure (KevinGross)

Torn the key to KOEO and let the pump prime. Go to the engine compartment with a rag and release the schrader valve. It should dump enough fuel to soak the rag pretty good.<p>Are you saying that the FP gauge wont screw on the schrader valve?<p>My gues is that your FP regulator is shot, You can take the insert out of the schrader valve and wormclamp a small piece of fuel hose to the shcrader and the testor and turn the key to KOEO. You should get right at 40 lbs of pressure.<p>Hope that helps<p>Gary
 

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Re: 94 850 - measuring fuel pressure (yellow95)

Gary,<p>Thanks for the reply. Yes, my FP gauge set doesn't have a fitting for the schrader valve. What worked, though, was simply to take a length of 3/8" fuel hose, remove the valve core, and clamp the hose to it with a 13 mm. Norma clamp (ie, solid metal band clamp).<p>Problem turned out to be a marginal coil, fuel pressure was fine. The coil impedences measured correct, it made a spark when I cranked with a plug out of its socket. Swap in another car's coil, and the engine runs. Coils are annoying!<p>Kevin
 

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So can your fuel pump if it is intermitant and going bad. You may want to check into that as well. Bosch fuel pressure regulators are perty bullet proof.
 
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