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TOTAL NEWBIE. One problem and many questions

Old May 20th, 2019, 1:41 AM
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Default TOTAL NEWBIE. One problem and many questions

Hello

I have been a Land Cruiser user all my life so, you know, didn't have to do much repair over many years. Plus it was super easy to diagnose any simple problems because when I opened the hood I could see all the engine from all sides. Not the case with the Chevy Express.


1. PROBLEM
My 2002 Express has the 5.7 engine with 90K miles on the clock. For the last 15 thousand miles it's been driving like a champ, never missed a beat. Until now... If I start the van on a daily basis it drives perfectly. If I let it sit for around 12-15 hours it starts right away (one crank and engine starts) and it drives perfectly. When I let is sit for over 24 hours it won't start. I need to crank it for half an hour until the battery can hardly make it and suddenly the van starts and from that time on it drives perfectly. I can start it anytime I want unless I let it sit for more than 24 hours.

PROBLEM DETAILS.
While trying to start the engine there is some stutter, something like a hiccup: I crank for 10 seconds, let off the key and the van burps a few times as if it were trying to start the engine. Half an hour later the van starts suddenly although with hesitation. I stomp on the gas and after 5 seconds of hesitation the engine revvs and operates normally.

MY THEORIES AND ASSUMPTIONS.
a. I think this might be a fuel problem. Something causes the fuel lines to lose fuel which returns to the tank. I need a lot of cranking to fill the lines again. Once fuel is delivered there are no misfires or stuttering, even on bumpy roads so it's nt an electrical issue.
b. There has to be a fuel pump in the tank. Maybe it's going bad. Like it no longer operates well on 12V but needs closer to 14V to deliver proper pressure. Dunno...
c. There has to be a fuel pump relay which gives the pump two working speeds. Maybe it's bad and doesn't turn on the pump. But on the other hand it drives perfectly once it starts.
d. A leaking injector would have filled the cylinder and seized the engine so that's probably not that. Engine cranks normally but simply doesn't start.
e. While I am cranking I can smell fuel but I have no fuel leaks from underneath although I had one big 'pop' sound, like a mini explosion which separated part of the intake, the plastic resonator which is after the air filter and air sensor. This backfire indicates that there must have been some fuel. Is there an additional starting injector in the Chevys?



QUESTIONS.

1. Could anybody help me narrow down the problem. I have no garage so when I start working on the van in front of everyone's building I want to be discreet, fast, efficient and not take apart the wrong parts.
2. Where do I download a Factory Service Manual for the Chevy Express? I used to have these for the Land Cruisers and they were very detailes, every part was shown, every circuit explained etc.

Many, many thanks :-)
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Old May 20th, 2019, 7:31 AM
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There is a check valve in the fuel pump. when it goes bad it lets the fuel drain back into the tank. Spray some starter fluid into the throttle body and if it starts , then the check valve is bad. In that case you can either replace the fuel pump assembly or add a check valve in the fuel line next to the tank.
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Old May 20th, 2019, 8:13 PM
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if you turn your key to the on position the fuel pump should pressurize the fuel rail......wait a few seconds before you try to start it so the pump can pressurize...
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Old May 20th, 2019, 9:49 PM
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repeat loopedr1 suggestion a few times before cranking.....it only cycles the pump a few seconds each time....
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Old May 20th, 2019, 10:20 PM
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Check your fuel pressure. If it's bleeding off you might need to replace the check valve, spider if it has one or fuel pressure regulator.
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Old May 21st, 2019, 11:39 AM
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Thanks for the replies. It indeed looks like it is the check valve in the pump. I was told by the previous owner that he changed the injectors (he was a mechanic and worked himself on the van) so I assume they are OK, which actually looks like the case as the van drives good.

Where can I get the factory service manual? I am not interested in Chilton manual as it is too vague, would prefer a link to the factory PDFs
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Old May 21st, 2019, 3:17 PM
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before replacing parts do like suggested and check the fuel pressure. it does sound like a fuel pump issue but i would check pressure before replacing parts
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Old May 22nd, 2019, 5:17 PM
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Regarding the FSM, HelmINC used to publish the FSM, but last time I checked it was no longer available/in print. So, your best bet is eBay, or equiv. That's where I got my (used) copy of the FSM for my '02 Express. It is a 3 volume book set, with well over 1000 pages. Worth every penny.

Peter

Last edited by MiragePilot; May 22nd, 2019 at 5:19 PM. Reason: typo
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