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2000 CHEV S10 cold start problem

Hi guys, any techs browsing?? : ) Complaint is difficult starting in morning, or even after being off for an hour. It just came in so haven't done much on it yet. No codes except evap small leak detected in history, none current. So far, confirm a little difficult after being off almost an hour, and starts fine repeatedly, except if I give it a little throttle (shouldnt need but should also tolerate it) it also starts rough... like it's flooding. Data looks normal so far, will check that again in the morning! No misfire. BUT, MAF show 1.92 g/sec NOT running. Is this acceptable? SnapOn values give range and it's within range otherwise. History is complete tune-up less than a year ago. His description for successful starting is to always hit starter as briefly as possible. It's almost like it only fires after you release the key. Crank and let go, and it might start... hold cranking and it won't. I'm planning fuel pressure check, and balance test in the morning. From there, I'm wondering about possible electrical fault involving no spark or something while cranking. I don't yet know if after successful cold start the problem is better, worse, or same if shut it off immediately and try again. I think he's always just got underway as soon as finally getting it to start! Any pointers much appreciated in the electrical possibilities. In2

Reply to
In2hoppn
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Sounds like a failing ignition switch. The "seems to fire after you release the key" is a common failure mode in the switch.

Reply to
Steve W.

UPDATE:

Fuel pressure only just under 50 psi... 54 psi max with repeated key cycling. Dump a small amount of fuel onto throttle plate, pop the top back on, and it fires right up. Cranking when it won't start drops the fuel pressure down around 40.

Pain in the Butt!!! See NO easy way to determine if it's actually the pump or regulator, as I don't imagine one can pinch off one of those plastic return lines????????? Seems I will either have to unhook the fuel lines from the injector (a real pain if it's like the V8's where you have to unclamp the lines down the back side of engine) and then jerry-rig a connection directly to the fuel line. Or, drop the tank and rig up a line feed from the pump directly to the gauge. Either way, hate messing with this "stinking" dangerous stuff : ). What pressure it does generate seems to hold steady. It leaks down eventually, but my stupid fuel gauge connection doesn't seal 100% to hold pressure for hours... I'm thinking I'll go with dropping the tank to check it, as I think the fuel pump itself is the most likely culprit, where as if the pressure built a little higher but dropped quickly I'd be more concerned with the regulator. Of course, will investigate plug connections as well. Pump "sounds" normal when cycling key. It's consistent so it doesn't strike me as an electrical fault, but remains a possibility.

Then, if diagnosis is such, next will be what to do for parts. I'll check with dealer, and price out aftermarket options as well. Price is an obvious factor, but so is availability. I've read bad comments on airtex, yet have had no problem with airtex in the past but for other applications! Experiences there would be appreciated. Is "replace pump only" even an option, or is it strictly "assembly" only.

Thanks, will update...

Reply to
In2hoppn

Won't be that hard. There are standard fittings right at the rear of the manifold.

The book I have has a bunch of tests to isolate the components. The pump test is basically pulling the feed line and dead heading it with a gauge. For the regulator you connect to the return line coming out of the manifold.

Or, drop the tank and

I have tried a bunch of pumps over the years. Have found duds in just about all of them! For long term I suggest either Delco or Carter. Fisher or NAPA can get either one. BUT the price can scare you! If it's not a rush order one from Rock Auto for a LOT less money.

2000 is pump module only.
Reply to
Steve W.

Actually, from the pump at top of tank, the have short plastic line that connect to steel lines sticking just above the frame rail. Not bad at all to reach right above frame and disconnect! Just bought a 5/16 repair type end, made it into a "slip on plug", and installed it onto the line after unplugging the return to the tank. No change in pressure at the test port. Pump wouldn't generate enough pressure to even need a return line to tank : ). Then took advantage of the pumps ability to move volume... connected a long hose to test port, pulled relay and jumpered to pump 3/4 tank of gas into cans : ). Pump did not sound good at all when free flow pumping. Sounded like it was falling apart inside but it emptied the tank Ok.

Got an OEM replacement. Not from dealer but still original brand, just can't remember the name now! It bugging me but I'm too tired to get my brain on it now. Not Delco, the other one...

I'll say this... among rusted bolts, and splicing on the updated plug type... all wasn't too bad except trying to fit that unit down into the O-ring and getting that big snap ring on it. Even with the o-ring well lubed... that is ONE TIGHT FIT! Maybe the occasional "evap small leak" code will be gone now?? : ) Time will tell. It's a code that's been documented from long ago...

I never did even follow up with a pressure check. The difference in starting in night and day. Fires as soon as it cranks. Sweet success!

Reply to
In2hoppn

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