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Discussion Starter · #1 ·
Hello folks and greetings from Virginia! Long time fan of this site and first time poster! I'm wondering if you guys can help me out with a problem with my 98 Astro Van. After a little work I have put into it, I got it to run after having it sit and not running for 6 years due to very hard starts with strong cranks. However the van stumbles on startup after about 6 seconds to the point of either nearly stalling then magically stays consistently running or....stalls. :|

Fuel pressure primes at 56psi with key on engine off, then drops to 46psi after priming, then slowly drops and holds to 36psi within 13mins. I was wondering if this GB remanufactured SCPI that I put into is the cause of this. The little place where the schrader-like star valve on the fuel pressure regulator is welded shut, the original SCPI I had was not like this, but I replaced it anyways without worry because I just wanted the van to run....... I'm wondering if the weld is my problem, possibly something ruptured inside the FPR because of the weld causing my problem?

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A little background on the work i did: I replaced the intake gaskets with Magnum brand gaskets (as well as other gaskets for plenum and TB) as well as replacing the thermostat and air filter. I also replaced the fuel filter after replacing the SCPI with a GB remanufactured SCPI (I know everyone here recommended the MPI but I didnt really think there was a big difference). After reassembling everything to specs, still no starts with hard cranks.

Bought a Fuel Pressure Tester and found that the PSI while pump primed with key in ON was 45 then dropped and held at 38 psi for more than 10 minutes after the pump primed. After a little inspecting, I decided to replace the fuel pump with a Delphi pump (the brand I found in the tank was an AIRTEX). Checked for pressure with key on before starting, primed at 56psi than to 46psi after priming then dropped to 34psi within 10 mins. I forgot what was the fuel psi was at cranking but......

Van started after a few cranks! First in 6 years! However like I said before, van stumbles after about 6 seconds and either dies or stays running after stumbling. It does this every time the van is started. Fuel pressure was erratic, between 50-55 if i remember correctly. I pinched the return line with key on engine off, fuel psi was still 56 primed than 46 psi after primed then dropping to 34psi within 10mins.

Any ideas??? Any thoughts would be appreciated, and if anymore info needed, i'll provide. I just been itching for several years to have the van in good working order so I can go to parks and places in Virginia and Maryland and take pictures of the van and my travels like I've been seeing you guys do for years. :D :D :D

P.S. First couple of starts had a high idle and threw a code for the TPS. I switched the whole throttle body to airbox assembly from my mother's work van to mine and the high idle went away along with the code. However it still stumbles after startup like mentioned before. Thanks guys for any ideas!!
 

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Agree with above the gas today is............. setting ONE year is disastrous. My 1999 Silverado sat three and was very reluctant to start and when it did it ran like ..... stumbled and stalled many times until about two days later I filled half full and added some additive to the tank. it is doing ok now but have to change vent solenoid thing on the frame and the coil on cylinder three. But my tank was dang close to empty so the old gas was very little in the tank. OLD but not much. Slowly working the stale gas out. My truck is a 5.3 not your 4.3 but old gas is old gas.
My 1995 Astro sat for two years and did the same but it was 3/4 full I had to empty the tank and refill with some fresh stuff. I took off the fuel filter and connected a long hose to the pipe from the tank and turned the key on. took three cans to get the smelly junk out. And about twenty minutes if I remember the time right.
 

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I agree with above too. Old gas can turn into a varnish type liquid and it is only good to light your brush pile after it sits a long time. Empty the tank replace the fuel filter fill it up with new gas and injector cleaner to clean out any residual crap left by the old gas. Thats what I did with our old bravada we bought it with old gas in the tank and it ran but ran horrible. Also if you left it sitting and have not done spark plugs, wires and any other parts that we used to call a tune up will need to be replaced. markmitch
 

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Discussion Starter · #6 ·
Thanks for the responses guys! I emptied the tank before starting it up the first time when I changed the injectors and filter. When I replaced the pump a little after I took out the gas because it only gas around that I could for my lawnmower, weed whacker, and chainsaw (summer brought a lot of brush along the fences :D ) and thoroughly cleaned out the tank before reinstalling with a Delphi pump and 5 gallons of new gas.

Van started after the pump change, however, noticed pressure never got above 56 psi when it first primed despite being new and other members mentioning their new pumps got psi in the 60s. That, plus after priming, drops to 46 psi than slowly drops and hold at 36. When running, the psi erratically goes between 50-55 at idle. I doubled check the wiring with a wire probe and it checked out great, no fuel leaking from the lines or on top of tank, no fuel leaking from the regulator itself. I want to look into seeing if the new pump is the problem, but rather check that one last if I need to drop it.

Plugs look okay (despite being autolite) and the distributor cap doesn't look like an original (compared to my 98 c/k). I do plan on replacing them, but I wanted to first find out why I can't get fuel pressure above 60psi like others on here after replacement of the pump, with mine slowly dropping in pressure until 36 psi. The van will run fine if I start it up and get past the stumbling after a few seconds. Pressure probably won't be at best. Have not attempted to drive it down the road because of the fear the van will cut out.

I was thinking maybe that strange weld on the FPR had something to do with my problem. The original injector assembly on the van was not like that, it had a star shaped shrader valve on it

Maybe first I should check to see if my pressure gauge works correctly first :lol: I'll check the fuel pressure on my mom's astro van tomorrow for a comparison then start some reassembling. If any thoughts come up let me know and keep warm, Big_kid I think you guys also got some flurries a little south? Haven't asked my brother in Blacksburg about how the weather was like there.
 
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