stc78

hi i have here today a 94 astro with a cold start problem,now ive checked the basics,
fuel pres 50-60 psi,
spark yes,
changed fuel filter,
no drop in presure when sitting (which would rule out spider right?)
starts and runs excellent with a little juice at startup (either)
after that starts once warm every time
runs beautifull very smoth and quiet

now for the interesting the van 4.3 w cpi,has 234,000 miles when i bought it had a hellatious rod knock but it still ran well, but it had the cold start problem, now i replaced the motor with a 100,000 mile canidate i had in the garage, finshed it up and it started right up ran perfect, note 60-70 degrees inside, put it outside next morning no start 20-30 degrees, a little juice and away we go

now ive heard people say something about a pulsator? but what does that acually do? would it cause my problem, fuel pump? and you know im looking for any excuse not to drop the tank, its been sitting for some time and its not pretty but im out of options.

ive been throgh every sensor and wire and im confident its not the electrical system, well ive been wrong before but pretty sure, it also has a new fuel pump relay

id appreciate any help or input you guys could shoot my way thanks a lot, man in disgust.

blkmonday

im in a similar situation...sure youve seen about 10 of my posts. from what i have heard. the fuel pump needs to run at at least 60psi at all times for the van to run correctly. mine currently runs at 54psi so im going for the pump next....i feel your pain and do not want to drop the tank either. i saw a procedure for making an access hatch from above for the pump but it just seems easier to drop the tank in my opinion. ive also heard the pumps on these years are faulty...im going aftermarket on mine...autozone has a master pump for 69 bucks, a pulsator for21bucks and a strainer for 7 bucks. not too bad if it fixes the problem. ill think of you when im dropping my gas tank...any tips or advice you come along in the meantime send them my way..ill do the same for you
good luck

astromaster

what did you find out about your cold start problem??

stc78

it was the fuel pump

Blue Bowtie

Are you certain? Did you diagnose it fully?

http://www.automotiveforums.com/vbul...d.php?t=370317

MT-2500

Pulsator is in the fuel tank on the fuel pump assembley if it has one .
It is a damper for fuel pressure bit if bad can leak fuel pressure.

Your fuel pressure readings are on the low side specs are 55/61.
You need 60 lbs on a cold start to squirt injectors.
Also it you have a fast leak down after key off you have a leak someplace.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
Yours should be 59-60 cold start.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/61 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back your fuel pressure readings.
MT

__________________
Remember proper testing gives us the answer to many problems.
MT

stc78

the pulsator on mine was allready gone and yes it was definetly the fuel pump a feww pounds really does make a difference trust me cause it starts every time now even if it sits in the cold for a week,(its for sale now $2000), hope that helps

rangerreb

I worked on a van with the same situation as yours and checked everything you checked sometimes it would run great and other times it would not even start. The guy told me he had tuned the van up so I checked a couple of the plugs and they looked pretty good. I checked for spark coming out of the coil to the distributer cap it was good. Finally, while I was sitting there thinking about everything I had done I realized that I did not check for fire at the plug. There it was big as day NO FIRE! I pulled the cap there was evidence of scattered carbon tracks all over the cap. I removed the ignition module and replaced it the cap and rotor. It is running great now. REB

rangerreb

Always check everything even if someone said they "Did that already"