Re: 95 4.3 vortec (Jimmy) ignition switch question on fuel delivery (crossposted)

Sorry to double post. I have a few tech questions if anyone wants to entertain them...

Does the 95 4.3L W series motor on this Jimmy SLT 4x4 have an accumulator/reservoir for residual fuel pressure capacity? As well, does this block use a 'cold start injector'? I have also pulled the intake manifold tuning valve and looked in with a light a mirror for clean, shiny hose connections, etc. to indicate a leak at an injector or the FPR (as stated there's no problem with fuel pressure that I can drill down). I have fuel and spark and no codes are printing currently with the engine running in perfect time, etc. I just cannot drill down this damn intermitent starting problem. Does this sound like a worn crank sensor??

Thanks and sorry once again for the duplicate rants. Andrew.

No.

No.

Not if you have spark when the no-start is occurring.

Thanks for the response. Do you have any ideas what else I should be looking into diagnostics-wise? The MAP reads dead on also at 28.9in Hg (with about +800 ft above sea level). I'm beside myself as to why the pump will power up with the test connector but not so every time with the ign (key in engine off). When it finally starts, it runs like a top. Thanks. Would it help to post the outputs from my scanner?? Andrew.

in article snipped-for-privacy@newsclstr02.news.prodigy.com, aarcuda69062 at snipped-for-privacy@sbcglobal.net wrote on 2/10/07 10:12 PM:

You need a wiring diagram and a test light to solve this problem. When no-start, check for voltage and ground at the pump and then work your way forward to the fuel pump relay and the ECM signal to it. Concentrate on any splices and grounds since thhat is where trouble usually shows up first.

Nope, doesn't sound like the problem is with anything that would be seen in the data stream.

Sounds like a fuel pump relay or perhaps the ECM is at fault!

No

OBD I and II both cycle the fuel pump relay on initial 'key on' for about a second and a half to initially pressurize the fuel rail. The relay then turns off and stays off until the computer either registers oil pressure and/or rotation via the crank sensor/distributor.

I would have to check a service manual but I believe 60 psi is a little high. Anyway, if the vehicle maintains fuel pressure during cranking then that rules out fuel pump problems. Move on to injector triggering and ignition.

Our intermittent starting problem occurred in high humidity, turned out to be a defective new part, distributor cap arcing only in high humidity would it short so bad as to not start.

"Charlie B" wrote in news:BKWdnb6qU61mQEjYnZ2dnUVZ snipped-for-privacy@centurytel.net:

actually i see 55 to 60 normally on the system being discusssed (keyon, engoff), dropping to about 52 with engine running....any security feature should also be considered...........kjun

Charlie, Thanks for the input. When you mention checking injector triggering are you talking about using noid lights? I guess the procedure for checking the poppets is a little different as they don't test like regular EFI systems as far as I know. I still can't for the life of me access the oil pressure switch. Any tips on this? Do I have to pull the plenum or the distributor? Thanks again! Andrew.

in article BKWdnb6qU61mQEjYnZ2dnUVZ snipped-for-privacy@centurytel.net, Charlie B at snipped-for-privacy@centurytel.net@centurytel.net wrote on 2/16/07 11:41 AM: