Hi!
I’ve got a 2002 Oldsmobile Bravada (4.2L I6) with 111,000 miles.
It's hard to start unless I cycle the key a couple of times to prime the system. Sometimes it stalls at red light but turn it back on and it's good for rest of the trip. I’ve already replaced/serviced: spark plugs, ignition coils, ignition switch, crankshaft & camshaft sensors (with relearn), MAP & coolant sensors, O₂ sensor, fuel pump, fuel filter, fuel cap, fuel pressure regulator (twice, now OEM-spec), fuel tank pressure sensor, purge valve, water pump, alternator, starter, valve cover gaskets, thermostat, oil pressure switch, variable valve timing solenoid, and I’ve cleaned the throttle body. Oils and maintenance are all up to date.
Even after all that, I think I still lose fuel pressure after shutdown since need to prime before starting, and it occasionally dies at idle. I've tried a few Fuel Injector cleaners and Seafoam but before planning to clean and rebuild the injectors next with new seals and filters, could the problem be a leaking injector or bad pump or check valve, or is there another common issue on these Bravadas that I should check?
No error codes always showing that everything is running smooth and fine, idle beautiful and steady. I have an 07 Trailblazer with same engine and same parts changed with 242,000 miles and it works like it's brand new. I'm really at a loss.
Thank you!
John
I’ve already replaced/serviced: spark plugs, ignition coils, ignition switch, crankshaft & camshaft sensors (with relearn), MAP & coolant sensors, O₂ sensor, fuel pump, fuel filter, fuel cap, fuel pressure regulator (twice, now OEM-spec), fuel tank pressure sensor, purge valve, water pump, alternator, starter, valve cover gaskets, thermostat, oil pressure switch, variable valve timing solenoid, and I’ve cleaned the throttle body.
This is possibly the most parts cannon ammunition I've ever seen on this site.
Did you replace every one of those things with AC Delco parts?
The lack of a fault code to leads me to think something is up with the fuel pump. Did you purchase a new AC Delco fuel pump? If so, what website did you purchase it from? Websites like eBay Motors and Amazon can be counterfeit parts.
could the problem be a leaking injector
No. The fact you need to "prime" engine means not enough fuel is getting to the injectors. If a fuel injector were stuck open (flooding the engine), you'd need to hold the throttle wide open and crank until it starts. If the car's ECU detects WOT on start-up, the fuel injectors cut off until it starts. That doesn't occur.
Get a fuel pressure guage from AutoZone. There's a Schrader valve on the fuel rail. Per Google AI, it should be between 52 and 59 PSI. This it what it brings up: https://www.2carpros.com/questions/oldsmobile-bravada-2002-oldsmobile-bravada-fuel-delivery
@justin-shepherd Thank you, that makes sense about the fuel injectors. The "parts canon" lol started because the car had been sitting a while and needed some work and spark plugs were seized so I began with the valve cover, spark plugs etc and figured while I am there I changed the water pump, alternator etc. 90% are AC Delco parts. However the Fuel pump I was unable to find AC Delco and went with Spectra which is a Canadian company that is "middle-tier aftermarket brand" and purchased that one from local parts store just in case.
While I've done many things myself including timing belts I only replaced injectors once on an Intrepid in 97 I believe. So I was wondering if an injector’s internal needle/pintle could be faulty and not shutting when the engine is off which would cause it to need priming?
Yes I just ordered a fuel pressure gauge. But from what you are saying, I am suspecting that the new gas pump might not be good enough. Had the same issue with the regulator, I cheaped out and realized the PSI wasn't strong enough, purchased the real thing and it drastically reduced the problem but still something happening.
@justin-shepherd PS And of course some of the parts were to eliminate about 11 codes on that car. But as I said now there are no codes whatsoever.
I think I still lose fuel pressure
better measure it. A lot could be wrong on a 23yo vehicle, including varnished/corroded/swollen fuel lines.
Also, aftermarket pump for these old GM are notoriously unreliable. Stick to delphi/delco.
went with Spectra
I'm reading people's experiences with these online, and they seem to last 6 weeks to 3 years, and some that lasted 300 miles, 400 miles, 1000 miles, one guy was left stranded 2 days later... Pretty dismal.
However the Fuel pump I was unable to find AC Delco and went with Spectra which is a Canadian company that is "middle-tier aftermarket brand" and purchased that one from local parts store just in case.
You might check some local junkyards for an AC Delco fuel pump. The Oldsmobile Bravada was based on the GMT360 platform, which was shared with the much more popular Chevy TrailBlazer. If GM produced the same engine in the TrailBlazer covering the same model years, it should be compatible. You're taking pot luck that it works, though. Try to find one from a truck that's been wrecked.