1994 s10 Blazer with 145,000 miles - vortec - 'W' engine.
Engine normally runs very smooth and without misfires either around city or highway. Starts first time, every time with very little cranking.
Now, VERY intermittently, the engine will be running smoothly, suddenly start sputtering, and die. (my experience was sitting still in the driveway) When this happens the engine will crank but not start. Typically it has to be left alone for 'a while' and then starts up normally (with very little cranking.) I have also experimented with disconnecting the battery and reconnecting it to trigger the re-learn
There are no engine codes or warnings.
Recent maintenance:

• distributor replacement (1/2 year ago on an unrelated issue)
• cleaned EGR valve
• replaced all vacuum hoses
• cleaned the ?valve? on top of the intake manifold
• replaced ignition lock assembly
• (thinking about the ignition switch itself on the column)
• I've traced back and looked at the wire going to the ignition coil but it seems to be fine.

I'm about at my wits end trying to figure this one out.
Any help would be appreciated.

 

Have you tried to watch the fuel pressure while its running and see what happens when it dies? The test gauges you can buy have a hose about 14 inches long, you can close the hood on the first latch without pinching the hose and have the gauge sticking out where you can see it as you drive. I have a similar problem where once a week it will just die while stopped at a light, it fires right up again. I havent put my gauge on yet to watch but its on my to do list once I get settled in at my new home.

 

Thanks for the reply.
I did fail to mention that I had also replaced the fuel pump/sending unit a few months ago. The funny thing about it is that it will not restart until it has 'sat' for a while. (although I do not know exactly how long that time period is - I left it overnight with the battery disconnected - reconnected it in the AM and it fired right up)
It's my daughter's car (and it's happened to her multiple times) but it's only happened to me (the sputtering and dying) once. I floored it (and held it down) trying to keep it running but it didn't work.
I was thinking about the fuel pressure regulator - but if it was that, I would think that I would have this problem all the time.

 

I would still recommend testing the fuel pressure not only for the pump running pressure, but also the leak down rate after the pump shuts off. If the pressure bleeds off, it could indicate a leaking FPR and/or fuel system internal to the engine which can cause a flooded engine.

What brand of pump did you use?

Ofcourse, that doesn't rule out something completely out of the ordinary... Could be an intermittent ignition switch failure. An intermittent/weak fuel pump relay... Etc.

 

Thanks for the reply
re: fuel pump - I actually don't remember but it was probably whatever brand Autozone sells for it.
I've thought about replacing the ignition switch on the strerring column. Do you think it might be worth the hassle?
re: tester for the fuel - where might such an animal be had? (or more accurately - where can I pick up a GOOD one?)
Thanks

 

As far as the fuel pressure gauge goes, some stores (autozone) have rentals that you pay for, but then get your money back when you return it. Worth checking out. I have a fuel pressure gauge from Advance Auto which as served me well for a very long time and many uses.

Aftermarket pumps are garbage IMO. Many have had problems with the Airtex, Bosch, Standard, etc aftermarket brands that most parts stores sell. AC Delco and Delphi are two of the recommended brands that others (myself included) have had good luck with.

 

I got mine at LORDCO auto parts when I was in BC Canada. It was 50-60 bucks and is good quality, a pro grade one (not needed) could cost you over 200 from Snap-On or someone else. Mine came with "T" and hoses to attach to imports. The only thing Ive found I didnt have is an adapter to join up with FORDS injector rails... I had to buy that little peice separately. Mine never came with a case so I got one at the dollar store to store it in. Its called exactly "Fuel Injection Pressure Tester". This is what I got, except this one comes with the ford adapter.
http://www.amazon.com/gp/product/ima...1&s=automotive

When you go buy one you should have these pressures:

When Key on Engine Off - 58-60psi
When Running - 55 psi or so
When shut off - it should hold 58-60 for longer than 5 minutes. this is where you may find your flood condition happenning causing your hard start. If the pressure is bleeding off it is leaking into your plenum or into the intake runners from the injector tippets, You will also get 'gassy' smelling motor oil if this is the case. Sniff your dipstick.

 

Thanks for the information.
re: 'normal' pressures - Ha, you answered my next question before my asking. Thanks
While I'm going to check the pressures out - the inconsistency with the random dying of the engine with no apparent cause still make me think the root cause is something electrically based. But then again, I may be barking up a wrong tree here. Anyway, thank you for your replies and I will add them to my list of things to do!

I'll check them out - thank you.
(I sure cannot remember what the brand of fuel pump that I put in the thing)

 

Thought for sure I had found the problem. The fuel pump relay (up on the firewall) connection was real bad - some of the 'pot' material had oozed down onto all the blade electrical connections - that made a lot of sense with the symptoms - when the car was run for 'a while' it would start missing and sputtering - IE. the relay would heat up, melt/liquidfy some pot material and then the material would ooze down into the electrical connection breaking the connection intermittantly.
Changed and cleaned that all out, even replace the other relay located there since they were the same and it had the same problem with oozing.
I just finished driving it about 60 miles - it was fine for the first 45 - smooth as silk - then it started intermittently sputtering/missing.
This problem is about to drive me crazy.
Haven't been able to check the fuel pressure or perform a leak down test yet. Waiting on my tool to arrive.
Anyone have any other suggestions??
Thanks

 

Pressure/leak-down test. You need to either verify it as the cause or rule it out.