2000 Astro hard to start when cold

2000 Astro hard to start when cold

Postby Tim Baker [OP] » January 24th 2011, 7:43pm

I have a 2000 Astro AWD 4.3L which has developed starting problems in the last few weeks. It initially turns over and no fire if I return the key wait 10 sec and turn back on to re-prime the system a few times it will either fire up or the battery runs too low. Get a jump and it starts almost right away and runs great all day unless I let it sit for a few hours and it gets cold then sometimes it fires up sometimes it doesn't and I have to get a jump.
I have it plugged into a block heater and the motor feels warm to the touch on the hoses and it spins over fine it just doesn't seem to get fuel when its cold. I was told it could be a check valve in the pump stuck open/shot allowing the fuel to drain back to the tank or far enough back from the motor that it takes too long to prime it to the top (or the 3-5 times I have to do it to get it to fire I also was told it may be a cold weather sensor on the block and the problem did start when we got sub zero temps in the last week however I can't find any info on such a part.
Also when it does start there is no sign of high idle even though the temp gauge shows its cold however it runs real smooth.


So far I have installed
Cap and rotor
wires
plugs
A.C.T. sensor
Had 1 year old battery checked, passed
Had alternator checked, passed
fuel pressure tested 61 lbs about a month ago
oil change
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Re: 2000 Astro hard to start when cold

Postby GMCGUY » January 25th 2011, 6:25am

From the first part it sounds like a bad battery, I know you said you had it checked but a good battery should be able to crank your engine for a good 30 seconds (But not continuously!) before the cranking even slows down, priming the pump a few times should NOT kill your battery! What you need to do is hook a voltmeter up to the battery terminals, first make sure you have at least 12 volts there, if your a couple volts low you may have a bad cell, this is actually pretty common and some cars don't even show signs until an odd problem like this arises, then crank the engine, if the voltage drops below 9 volts during cranking you either have a bad battery, a bad connection, or your starter could be drawing too much juice, excessive starter draw is the only reason a "good" battery would go dead that quick, does it sound like its cranking quickly? Also, did you have any check engine light on before this problem started, its possible that a bad maf sensor would tell the computer to run in limp mode where it uses the intake air temp to help calculate fuel, it may see -10 degrees from the air temp sensor and the engine coolant is 115 degrees from the block heater, therefore giving it conflicting information and feeding itself with an incorrect amount of fuel, this is far fetched but I've seen wierder things! Check cranking voltage first! Check your connections and if that all checks out then move onto checking fuel pressure, since its kindof a pain I would rule out the other stuff first, but once you get to fuel pressure you may find the "check valve" a leaky pressure regulator or possibly leaky injectors, maybe even a weak fuel pump, but you can't get a good test until you are 100% sure the battery is good. Let us know what you find or any other questions. Good luck!
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Re: 2000 Astro hard to start when cold

Postby Tim Baker [OP] » February 4th 2011, 3:15am

Thanks for the reply, yesterday it was -8F block heater plugged in all night I primed it, hit the key spun it a few times nithing re primed it hit the key and boom it was running fine. Today it was plugged in all night and the start temp was +6F and all it did was turn over until the 5th try and it started to fire I put it on the booster and on the 2nd try it fired up like it had been running all day.

Should I notice a "fast idle" when cold? I hear the idle raise and lower like someone is gently feathering the gas and when its warm it does not do this.
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Re: 2000 Astro hard to start when cold

Postby fast68 » February 4th 2011, 10:05am

kind of confusing as to whether oyure actually having cranking issues or just starting issues


if cranking over issues then check cables all for tightness and clean dry connections

check battery for full voltage in it

you want to see 13.8 to 14.5 volts in the system when engine is running if it is healthy and all working properly


if the battery is over 4 years old then have it checked, it may have lost a cell


starter motor may be getting weak, and/or bendix/solenoid.

temp sensor in intake manifold may be faulty and not telling the PCM or ECM that its cold, and so that could be why not cold fast idle speed

also IAC may need to be removed and cleaned, in which is probably carboned up pretty badly if its never been pulled and cleaned yet.

difficult to start, but cranks over fine would be a number of other issues.,

weak dying FP

dying or intermittent working FP relay, or bad connection of it,

worn bad condition cap/rotor button

FP regulator should be full pressure nice to injector rail when no vacuum is applied to it, IE at cranking time,

check see if its ruptured by removing vacuum hose to it right after it was running, see if theres any raw gas in the hose.

if so then replace the regulator it is ruptured and allowing raw fuel to suck right into the intake/throttle

this is what causes the later 1990s plastic 3800 GM upper plenums to explode into pieces. kaboom!
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Re: 2000 Astro hard to start when cold

Postby redfury » February 7th 2011, 4:19am

If it seems that the booster battery is doing the job getting the van started more often than not, my guess would be to look at the ground connection from the battery to the chassis. Remove the ground and take a multimeter and check for continuity ( ohms ) from the battery side of the ground cable to another good ground ( such as the alternator or A/C compressor ). It should peg an analog meter. If it's showing a lot of resistance, then the ground cable is either corroded, or you have a bad connection on the other end.

That's where I would start in regards to the battery. One thing that you might want to gauge that on before doing a bunch of extra work though, is to look at your ammeter gauge in the dash. How many volts is it showing? If it's reading higher than roughly 15v, then the alternator is trying to make up for a weak battery, or a bad connection.

If that all checks out, then I'd be more interested in the fuel system...but reading your description, I'd bet you can't lay down the CCA's needed to get the van started reliably, even with a new battery. How many CCA is the new battery? ( cold cranking amps )
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