Hi I have a 1996 Chevy Blazer...I recently did the MFI conversion because I was getting a misfire code cyl 1. I changed the plugm distributor cap, and such. I noticed that the starter seems to be getting a workout starting the vehicle. If i don't "prime" the fuel pump once or twice it turns over several times before firing up. the only frequent code I am getting is the "catalyst efficiency below threshhold" Mods- 4" air filter and pipe into stock MAF<(descreened), and Thrush Muffler dumped before rear axle.

 

the idle when warmed up jumps a couple/few hundred RPMs up and down as if the engine is missing or something

 

Have you checked your fuel pressure? I think the code you are getting is unrelated to your starting issue.

 

Diaita, thanks for replying...Yes actually there seems to be an issue there too possibly. Key On Engine Off fuel pressure reads at 60psi, then drops to 0psi within 3 or 4 seconds. Massive bleed-out. Key On Engine On: fuel pressure steady at 50-51psi. Prior to all the problems I had a cyl 1 missfire which is why I replaced the "poppet spider" with the new "MFI spider" I have a live data scanner, but I'm not really sure what to look for. Its eating gas like crazy. Also the coolant gauge reads a few notches past 210, but the Live Scan shows that after being driven for 20 min or so the temp "actually" hovers around 187+/-, which seems a bit low. (thermostat has been replaced in the last 6 months). it does open up

I'm leaning toward vac leak at plenum, or fuel pressure regulator...

 

Now that you've determined that it is failing the fuel leakdown test you should go deeper to isolate the problem. This link goes deeper. Read the posts by Captain Hook. https://blazerforum.com/forum/2nd-ge...d-75428/page3/

 

Thanks for the link, I guess it just reinforced what problems I'm having. I believe the pump is stock, or original. I bought the blazer in 2005 and haven't changed it myself. The fuel filter has been changed twice. I guess I need a good semi warm day to pull the plenum back off and see if fuel is leaking in the intake??? Its getting horrible mileage, so I think the fuel pump is having no problem sending gas to the motor. Maybe its burning it up excessively

 

live scan update: the was taken at idle (550-600rpms) 194*F:

 

additional

 

Sounds like fuel pump time and small vac leak for the surging. New reg. should have come on the upgrade.

 

@ idle and warm 194*F

are there any other live data sensors that would help?